In this work, we have implemented an accurate machine-learning approach for predicting various key analog and RF parameters of Negative Capacitance Field-Effect Transistors (NCFETs). Visual TCAD simulator and the Python high-level language were employed for the entire simulation process. However, the computational cost was found to be excessively high. The machine learning approach represents a novel method for predicting the effects of different sources on NCFETs while also reducing computational costs. The algorithm of an artificial neural network can effectively predict multi-input to single-output relationships and enhance existing techniques. The analog parameters of Double Metal Double Gate Negative Capacitance FETs (D2GNCFETs) are demonstrated across various temperatures ($T$), oxide thicknesses ($T_{ox}$), substrate thicknesses ($T_{sub}$), and ferroelectric thicknesses ($T_{Fe}$). Notably, at $T=300K$, the switching ratio is higher and the leakage current is $84$ times lower compared to $T=500K$. Similarly, at ferroelectric thicknesses $T_{Fe}=4nm$, the switching ratio improves by $5.4$ times compared to $T_{Fe}=8nm$. Furthermore, at substrate thicknesses $T_{sub}=3nm$, switching ratio increases by $81\%$ from $T_{sub}=7nm$. For oxide thicknesses at $T_{ox}=0.8nm$, the ratio increases by $41\%$ compared to $T_{ox}=0.4nm$. The analysis reveals that $T_{Fe}=4nm$, $T=300K$, $T_{ox}=0.8nm$, and $T_{sub}=3nm$ represent the optimal settings for D2GNCFETs, resulting in significantly improved performance. These findings can inform various applications in nanoelectronic devices and integrated circuit (IC) design.

The symmetry requirements for realizing unconventional compensated magnets with spin-polarized bands such as altermagnets have recently been uncovered. The most recent addition to this family of magnets is parity-odd or $p$-wave magnets. We demonstrate that $p$-wave magnets are perfectly compatible with superconductivity due to the spin polarization of their electron bands and that they induce unexpected spin transport phenomena. We first show that $p$-wave magnetism can coexist with conventional superconductivity regardless of the magnitude of the spin splitting. We then predict that $p$-wave magnets induce a charge-to-spin conversion, which can be strongly enhanced by the presence of superconductivity providing a way to probe the coexistence in experiments. Our results open a new avenue for material combinations with a synergetic relation between spintronics and superconductivity.

We analyze the phase transition between a symmetric metallic parent state and itinerant altermagnetic order. The underlying mechanism we reveal in our microscopic model of electrons on a Lieb lattice does not involve orbital ordering, but derives from sublattice interference.

We present new atomistic models of amorphous silicon (a-Si) and hydrogenated amorphous silicon (a-Si:H) surfaces. The a-Si model included 4096 atoms and was obtained using local orbital density functional theory. By analyzing a slab model (periodic in two dimensions with a slab about 44 \AA{} thick), we observed a strong correlation between surface structure and surface charge density, which might be compared to STM experiments. Hydrogen atoms added near the under-coordinated surface atoms passivate dangling bonds and induce structural rearrangements. We analyze the electronic structure, including the localization of the states, and note resonant mixing between bulk and surface defect structures. We also compute the classical normal modes of the hydrogenated a-Si and compare them to experiments where possible. Our work is a step toward understanding the meaning of ``surface reconstruction" for a noncrystalline material.

The Sachdev-Ye-Kitaev (SYK) model is a cornerstone in the study of quantum chaos and holographic quantum matter. Real-world implementations, however, deviate from the idealized all-to-all connectivity, raising questions about the robustness of its chaotic properties. In this work, we investigate a quadratic SYK model with distance-dependent interactions governed by a power-law decay. By analytically and numerically studying the spectral form factor (SFF), we uncover how the single particle transitions manifest in the many-body system. While the SFF demonstrates robustness under slightly reduced interaction ranges, further suppression leads to a breakdown of perturbation theory and new spectral regimes, marked by a higher dip and the emergence of a secondary plateau. Our results highlight the interplay between single-particle criticality and many-body dynamics, offering new insights into the quantum chaos-to-localization transition and its reflection in spectral statistics.

The current fluctuation in one-dimensional driven diffusive systems is reported to have a upper bound that is set by its mean value together with the driving force. The resulting inequality arises from interactions between the diffusive particles, and the bound is approached in near-equilibrium systems or far-from-equilibrium systems with weak interactions between the diffusive particles. Three systems of increasing physical complexity are used to illustrate how the inequality is arrived at. The first system consists of only two reservoirs with particles randomly exchange between them at constant rates. For this system, the bound is shown to be saturated. The second one is the symmetric simple exclusion process, where the inequality is rigorously proven. The third one is the transport of charged particles driven by an external electric field, and numerical studies for this system also support the existence of the inequality.

The recent observation of superconductivity in the vicinity of insulating or Fermi surface reconstructed metallic states has established twisted bilayers of WSe$_2$ as an exciting platform to study the interplay of strong electron-electron interactions, broken symmetries and topology. In this work, we study the emergence of electronic ordering in twisted WSe$_2$ driven by gate-screened Coulomb interactions. Our first-principles treatment begins by constructing moir\'e Wannier orbitals that faithfully capture the bandstructure and topology of the system and project the gate-screened Coulomb interaction onto them. Using unbiased functional renormalization group calculations, we find an interplay between intervalley-coherent antiferromagnetic order and chiral, mixed-parity $d/p$-wave superconductivity for carrier concentrations near the displacement field-tunable van-Hove singularity. Our microscopic approach establishes incommensurate intervalley-coherent antiferromagnetic spin fluctuations as the dominant electronic mechanism driving the formation of superconductivity in $\theta = 5.08^{\circ}$ twisted WSe$_2$ and demonstrates that nesting properties of the Fermi surface sheets near the higher-order van-Hove point cause an asymmetric density dependence of the spin ordering as the density is varied across the van-Hove line, in good agreement with experimental observations. We show how the region of superconducting and magnetic order evolves within the two-dimensional phase space of displacement field and electronic density as twist angle is varied between $4^{\circ} \dots 5^{\circ}$.

There are now many examples of gapped fracton models, which are defined by the presence of restricted-mobility excitations above the quantum ground state. However, the theory of fracton orders remains in its early stages, and the complex landscape of examples is far from being mapped out. Here we introduce the class of planon-modular (p-modular) fracton orders, a relatively simple yet still rich class of quantum orders that encompasses several well-known examples of type I fracton order. The defining property is that any non-trivial point-like excitation can be detected by braiding with planons. From this definition, we uncover a significant amount of general structure, including the assignment of a natural number (dubbed the weight) to each excitation of a p-modular fracton order. We identify simple new phase invariants, some of which are based on weight, which can easily be used to compare and distinguish different fracton orders. We also study entanglement renormalization group (RG) flows of p-modular fracton orders, establishing a close connection with foliated RG. We illustrate our general results with an analysis of several exactly solvable fracton models that we show to realize p-modular fracton orders, including Z_n versions of the X-cube, anisotropic, checkerboard, 4-planar X-cube and four color cube (FCC) models. We show that each of these models is p-modular and compute its phase invariants. We also show that each example admits a foliated RG at the level of its non-trivial excitations, which is a new result for the 4-planar X-cube and FCC models. We show that the Z_2 FCC model is not a stack of other better-studied models, but predict that the Z_n FCC model with n odd is a stack of 10 4-planar X-cubes, possibly plus decoupled layers of 2d toric code. We also show that the Z_n checkerboard model for n odd is a stack of three anisotropic models.

Color centers in diamond, such as the GeV center, are promising candidates for quantum-based applications. Here, we investigate the impact of strain on the zero-phonon line (ZPL) position of GeV$^0$. Both hydrostatic and linear strain are modeled using density functional theory for GeV$^0$ concentrations of $1.61$ \% down to $0.10$ \%. We present qualitative and quantitative differences between the two strain types: for hydrostatic tensile and compressive strain, red-and blue-shifted ZPL positions are expected, respectively, with a linear relation between the ZPL shift and the experienced stress. By calculating the ZPL shift for varying GeV$^0$ concentrations, a shift of $0.15$ nm/GPa ($0.38$ meV/GPa) is obtained at experimentally relevant concentrations using a hybrid functional. In contrast, only red-shifted ZPL are found for tensile and compressive linear strain along the $\langle100\rangle$ direction. The calculated ZPL shift exceeds that of hydrostatic strain by at least one order of magnitude, with a significant difference between tensile and compressive strains: $3.2$ and $4.8$ nm/GPa ($8.1$ and $11.7$ meV/GPa), respectively. In addition, a peak broadening is expected due to the lifted degeneracy of the GeV$^0$ $e_g$ state, calculated to be about $6$ meV/GPa. These calculated results are placed in perspective with experimental observations, showing values of ZPL shifts and splittings of comparable magnitude.

For a long time, the study of thermal effects at three-dimensional (3D) short-ranged wetting transitions considered only the effect of interfacial fluctuations. We show that an entropic Casimir contribution, missed in previous treatments, produces significant effects when it is included; in particular, mean-field predictions are no longer obtained when interfacial fluctuations are ignored. The Casimir term arises from the many different microscopic configurations that correspond to a given interfacial one. By employing a coarse-graining procedure, starting from a microscopic Landau-Ginzburg-Wilson Hamiltonian, we identify the interfacial model for 3D wetting and the exact form of the Casimir term. The Casimir contribution does not alter the Nakanishi-Fisher surface phase diagram; it significantly increases the adsorption near a first-order wetting transition and completely changes the predicted critical singularities of tricritical wetting, including the nonuniversality occurring in 3D arising from interfacial fluctuations. We illustrate how the Casimir term leads to a reappraisal of the critical singularities at wetting transitions.

The hybrid perovskites [CH$_3$NH$_3$]Co$_x$Ni$_{x-1}$(HCOO)$_3$ with $x$ = 0, 0.25, 0.5, 0.75 and 1.0 possess multiple phase transitions including incommensurate structures. [CH$_3$NH$_3$]Ni(HCOO)$_3$ has also been found to have a proper magnetic incommensurate structure in its ground state. We have carried out a detailed structural characterization of the isomorphous [CH$_3$NH$_3$]Fe(HCOO)$_3$ (1) to investigate whether it also has incommensurate structural and magnetic modulations. We confirm that 1 crystallizes in the $Pnma$ space group at room temperature (RT) with a perovskite structure. Upon cooling, at about 170 K, the occurrence of new satellite reflections in the diffraction pattern show a phase transition to a modulated structure, which could be refined in the $Pnma(00\gamma)0s0$ super space group with $q_1~=~0.1662(2)c^\ast$. On further cooling to 75 K the satellite reflections become closer to the main reflections, indicating a new phase transition that keeps the super space group invariant but changes the modulation wave vector, $q_2~=~0.1425(2)c^\ast$. The structure then does not change structural phase down to base temperature (2 K). Magnetic susceptibility measurements collected under field-cooled and zero-field-cooled reveal a 3D antiferromagnetic order below 17 K. The overlapping in temperature between structural modulation and long-range magnetic order presents a unique opportunity to study magneto-structural coupling. Our results point to an improper modulated structure where interestingly the spins oriented strictly antiferromagnetic are perpendicular to those of previously reported compounds. In the present work, a combination of magnetometry measurements, single crystal and powder neutron diffraction and density functional theory calculations have been used to accurately determine and understand the sequence of nuclear and magnetic phases present in compound 1.

Gaining a deeper understanding of the interplay between charge density wave (CDW) order and superconductivity in transition metal dichalcogenides (TMDs), particularly within the (4H/2H)-NbX$_{2}$ (X=Se,S) family, remains an open and intriguing challenge. A systematic microscopic study across various compounds in this family is therefore required to unravel this complex interplay. Here, we report on muon spin rotation and magnetotransport experiments investigating the effects of hydrostatic pressure on the superconducting transition temperature ($T_{\rm c}$), the temperature-dependent magnetic penetration depth ($\lambda_\mathrm{eff}$), and the charge density wave order (CDW) in two layered chalcogenide superconductors: 4H-NbSe$_{2}$, which exhibits CDW order, and 2H-NbS$_{2}$, which lacks such order. Our observations reveal a substantial 75$\%$ enhancement of the superfluid density ($n_{s}/m^{*}$) in 4H-NbSe$_{2}$ upon maximum applied pressure of 2 GPa, surpassing that of 2H-NbSe$_{2}$. Despite the absence of CDW order, a sizeable 20$\%$ growth in superfluid density is also observed for 2H-NbS$_{2}$ under an applied pressure of 1.8 GPa. Notably, the evaluated superconducting gaps in all these TMDs remain largely unaffected by changes in applied pressure, irrespective of pressure-induced partial suppression of CDW order in (4H/2H)-NbSe$_{2}$ or its general absence in 2H-NbS$_{2}$. These results underscore the complex nature of pressure-induced behaviors in these TMDs, challenging a simplistic view of competition solely between CDW order and superconductivity. Remarkably, the relationship between $n_{s}/m^{*}$ and $T_{\rm c}$ exhibits an unconventional correlation, indicating a noteworthy similarity with the behavior observed in cuprate, kagome, and iron-based superconductors.

We present an innovative application of tensor networks to the study of current fluctuations in a typical one-dimensional diffusion-reaction system -- semiconductor. Two kinds of species of charge carriers, holes and electrons, diffuse in this system with the pair-generation and -recombination reaction occurring between them. The tensor networks are used to numerically calculate the cumulant generating function of the current statistics. By comparing the cases whether the reaction is turned on or off, the influence of the reaction on current fluctuations is clearly manifested, and this provides a numerical evidence of an interesting inequality setting an upper bound on the diffusivity in terms of the mean current and the driving force or affinity.

Topological insulators are characterized by insulating bulk states and robust metallic surface states. Band inversion is a hallmark of topological insulators: at time-reversal invariant points in the Brillouin zone, spin-orbit coupling (SOC) induces a swapping of orbital character at the bulk band edges. In this work, we develop a novel method to detect band inversion within continuum quantum Monte Carlo (QMC) methods that can accurately treat the electron correlation and spin-orbit coupling crucial to the physics of topological insulators. Our approach applies a momentum-space-resolved atomic population analysis throughout the first Brillouin zone utilizing the L\"owdin method and the one-body reduced density matrix produced with Diffusion Monte Carlo (DMC). We integrate this method into QMCPACK, an open source ab initio QMC package, so that these ground state methods can be used to complement experimental studies and validate prior DFT work on predicting the band structures of correlated topological insulators. We demonstrate this new technique on the topological insulator bismuth telluride, which displays band inversion between its Bi-p and Te-p states at the $\Gamma$-point. We show an increase in charge on the bismuth p orbital and a decrease in charge on the tellurium p orbital when comparing band structures with and without SOC. Additionally, we use our method to compare the degree of band inversion present in monolayer Bi$_2$Te$_3$, which has no interlayer van der Waals interactions, to that seen in the bulk. The method presented here will enable future, many-body studies of band inversion that can shed light on the delicate interplay between correlation and topology in correlated topological materials.

Charge order has been a central focus in the study of cuprate high-temperature superconductors due to its intriguing yet not fully understood connection to superconductivity. Recent advances in resonant inelastic x-ray scattering (RIXS) in the soft x-ray regime have enabled the first momentum-resolved studies of dynamic charge order correlations in the cuprates. This progress has opened a window for a more nuanced investigation into the mechanisms behind the formation of charge order (CO) correlations. This review provides an overview of RIXS-based measurements of dynamic CO correlations in various cuprate materials. It specifically focuses on electron-doped cuprates and Bi-based hole-doped cuprates, where the CO-related RIXS signals may reveal signatures of the effective Coulomb interactions. This aims to explore a connection between two central phenomena in the cuprates: strong Coulomb correlations and CO-forming tendencies. Finally, we discuss current open questions and potential directions for future RIXS studies as the technique continues to improve and mature, along with other probes of dynamic correlations that would provide a more comprehensive picture.

The density-density response in optimally doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ has recently been shown to exhibit conformal symmetry. Using, the experimentally inferred conformal dynamic susceptibility, we compute the resultant quantum Fisher information (QFI), a witness to multi-partite entanglement. In contrast to a Fermi liquid in which the QFI is approximately temperature independent much below the Fermi energy scale, we find that the QFI increases as a power law at low temperatures but ultimately extrapolates to a constant at $T=0$. The constant is of the form, $\omega_g^{2\Delta}$, where $\Delta$ is the conformal dimension and $\omega_g$ is the UV cutoff which is on the order of the pseudogap. As this constant {depends on both UV and IR properties}, it illustrates that multipartite entanglement in a strange metal exhibits UV-IR mixing, a benchmark feature of doped Mott insulators as exemplified by dynamical spectral weight transfer. We conclude with a discussion of the implication of our results for low-energy reductions of the Hubbard model.

We analyze the stress tensor and the gyration tensor of an unentangled polymer melt under flow by using a Rouse-type single chain model. We employ the bead-spring type single chain model, in which beads interact each other via nonlinear potentials such as the finite-extensible nonlinear elasticity (FENE) potential. Beads are assumed to obey the Langevin equation with a constant friction coefficient. We derive simple yet general relations between the stress tensor and the gyration tensor for this Rouse-type model, without any additional approximations. Various formulae for rheological quantities in terms of the gyration tensor can be derived from the general relations. For example, the steady shear viscosity is governed by the gyration radius in the shear gradient direction.

We present an experimental study on the collective behavior of macroscopic self-propelled particles that are externally excited by light. This property allows testing the system response to the excitation intensity in a very versatile manner. We discover that for low excitation intensities, clustering at the boundaries is always present, even when this is prevented by implementing flower-shaped confining walls. For high excitation intensities, however, clusters are dissolved more or less easily depending on their size. Then, a thorough analysis of the cluster dynamics allows us to depict a phase diagram depending on the number of agents in the arena and the excitation intensity. To explain this, we introduce a simple kinetic model where cluster evolution is governed by a balance between adsorption and desorption processes. Interestingly, this simple model is able to reproduce the phase space observed experimentally.

We discuss a large class of non-relativistic continuum field theories where the Euclidean spatial symmetry of the classical theory is violated in the quantum theory by an Adler-Bell-Jackiw-like anomaly. In particular, the continuous translation symmetry of the classical theory is broken in the quantum theory to a discrete symmetry. Furthermore, that discrete symmetry is extended by an internal symmetry, making it non-Abelian. This presentation streamlines and extends the discussion in [1]. In an Appendix, we present an elementary introduction to 't Hooft and Adler-Bell-Jackiw anomalies using a well-known system.

Majorana and trivial Andreev bound states are predicted to appear in superconductor-semiconductor hybrid systems, but their identification is still a challenging task. Here we consider superconducting junctions with Rashba spin-orbit coupling and explore the signatures of Majorana and trivial Andreev bound states in the emergent superconducting correlations when the systems are subjected to an external Zeeman field. We first show that robust zero-energy Andreev bound states naturally appear due to confinement and helicity when the normal sector of the junction becomes helical. These Andreev states can evolve into Majorana states, developing alike oscillations around zero energy as a function of Zeeman field. Unlike Majorana states located at both ends, helical Andreev states are located at the interface. We then demonstrate that the emergent superconducting correlations are locally composed of even-frequency spin-singlet even-parity and odd-frequency spin-triplet even-parity pair amplitudes, which coexist due to the interplay of spin-orbit coupling, Zeeman field, and spatial translation invariance breaking. In the helical regime, trivial Andreev states enhance odd-frequency spin-triplet pairing, which decays in the superconductor and has a homogeneous long-range profile in the normal region. At zero frequency, however, odd-frequency spin-triplet pairing vanishes in the helical regime. In the topological phase, Majorana states enhance odd-frequency spin-triplet pairing, producing a long-range homogeneous leakage into the normal region. Interestingly, we discover that when Majorana states are truly zero-energy modes, odd-frequency pairing develops a divergent low-frequency profile, which we interpret as the unambiguous self-conjugated Majorana signature. Our results help understand Majorana and trivial Andreev states from a superconducting correlations perspective in Majorana devices.

Inspired by the principle of equal probability proposed by Boltzmann in the 1870s, we establish a theoretical framework for the most probable distribution of meta-structures in materials. Furthermore, we validate the reliability of this theoretical framework based on statistical results of these meta-structures within randomly generated binary alloys. Finally, combining this theoretical framework, the high-throughput first-principles computations and machine learning, we determine the atomic chemical potentials in the binary FeCr alloy, thereby providing a demonstrative application. This theoretical framework will open a new research area and lay a foundation for the atomic-scale design of targeted properties.

In this thesis, we theoretically examine the pairing mechanisms and the identification of the pairing symmetry of unconventional superconductors whose normal states are correlated, multiband, or topological. In the first part, we investigate whether fluctuating intra-unit-cell loop currents can drive unconventional superconductivity. For general systems, we find that even-parity loop currents are not an effective pairing glue, whereas odd-parity loop currents, such as those proposed to explain the cuprates, are strong pair-breakers, suppressing rather than enhancing Cooper pairing. By employing the same methodology, we also analyze quantum-critical pairing due to other intra-unit-cell orders. For cuprates, we review the evidence for intra-unit-cell loop currents in the pseudogap, we classify the possible loop-current and particle-hole orders in the Emery model, and we analyze the pairing due to the various possible loop-current orders. In the second part, we present a novel electronic pairing mechanism that is based on electric monopole-dipole interactions. We show that these interactions become enhanced in quasi-2D systems with strong parity-mixing and spin-orbit coupling, such as doped Bi$_2$Se$_3$ or SnTe, and that they induce unconventional odd-parity superconductivity. In addition, we establish that the proposed pairing glue is measurable in the out-of-plane optical conductivity. In the last part, we reexamine the pairing symmetry of Sr$_2$RuO$_4$ in light of recent experiments. By theoretically analyzing recent $T_c$ and elastocaloric measurements under uniaxial stress, we demonstrate that the pairing state includes $s$, $d_{x^2-y^2}$, or body-centered $d_{xz} + i d_{yz}$ admixtures and that a bulk two-component superconductivity requires a great deal of fine-tuning to be consistent with ultrasound experiments.

Analytical results are presented for the structure of networks that evolve via a preferential-attachment-random-deletion (PARD) model in the regime of overall network growth and in the regime of overall contraction. The phase transition between the two regimes is studied. At each time step a node addition and preferential attachment step takes place with probability $P_{\rm add}$, and a random node deletion step takes place with probability $P_{\rm del} = 1 - P_{\rm add}$. The balance between growth and contraction is captured by the parameter $\eta = P_{\rm add} - P_{\rm del}$, which in the regime of overall network growth satisfies $0 < \eta \le 1$ and in the regime of overall network contraction $-1 \le \eta < 0$. Using the master equation and computer simulations we show that for $-1 < \eta < 0$ the time-dependent degree distribution $P_t(k)$ converges towards a stationary form $P_{\rm st}(k)$ which exhibits an exponential tail. This is in contrast with the power-law tail of the stationary degree distribution obtained for $0 < \eta \le 1$. Thus, the PARD model has a phase transition at $\eta=0$, which separates between two structurally distinct phases. At the transition, for $\eta=0$, the degree distribution exhibits a stretched exponential tail. While the stationary degree distribution in the phase of overall growth represents an asymptotic state, in the phase of overall contraction $P_{\rm st}(k)$ represents an intermediate asymptotic state of a finite life span, which disappears when the network vanishes.

This study proposes the correlation between intrinsic and tracer diffusion coefficients, considering actual molar volumes of the diffusing elements established in guidance to earlier analysis proposed by Manning. Manning established this correlation by assuming constant molar volume variation and mentioning the need for correction when molar volume is not constant. On the other hand, molar volume variation is never exactly constant, which may vary ideally or non-ideally in solid solutions. A recent study in the binary systems indicates that consideration of molar volumes of the elements following the ideal variation, when actual non-ideal molar volume variation is not available, estimated more accurate data instead of consideration of constant molar volume variation. The same is expected for ternary and multicomponent systems. This could not have been practised earlier because of the non-availability of this correlation between intrinsic and tracer diffusion coefficients, but it is possible now with the analysis proposed in this article. This correlation for constrained diffusion couples, such as binary and pseudo-ternary diffusion, is also established. Therefore, the outcome of this study is expected to bring a major change in diffusion analysis in ternary and multicomponent systems in future.

Sixfold-degenerate valleys in Si have attracted considerable attention for valleytronics application. Using optical pump-terahertz (THz) probe spectroscopy, we study the dynamics of valley polarization in bulk Si(001) at room temperature. Linearly polarized pump pulses excite electrons and holes with asymmetric distributions in momentum space, leading to in-plane anisotropic conductivity. By varying the polarization directions of the pump light relative to the in-plane crystalline axes, the valley polarization of electrons and the momentum asymmetry of holes are separately probed through observing the polarization rotation of THz pulses. We demonstrate that the valley relaxation time of electrons near the conduction band minimum exceeds 1.5 ps at room temperature, in good agreement with theoretically calculated intervalley phonon scattering with f-process. This work paves the way for Si-based room-temperature valleytronics.

Temperature rise of qubits due to heating is a critical issue in large-scale quantum computers based on quantum-dot (QD) arrays. This leads to shorter coherence times, induced readout errors, and increased charge noise. Here, we propose a simple thermal circuit model to describe the heating effect on silicon QD array structures. Noting that the QD array is a periodic structure, we represent it as a thermal distributed-element circuit, forming a thermal transmission line. We validate this model by measuring the electron temperature in a QD array device using Coulomb blockade thermometry, finding that the model effectively reproduces experimental results. This simple and scalable model can be used to develop the thermal design of large-scale silicon-based quantum computers.

The crystal structure, stability, electronic and optical properties of the Ta$_2$NiSe$_5$ monolayer have been investigated using first-principles calculations in combination with the Bethe-Salpeter equation. The results show that it is feasible to directly exfoliate a Ta$_2$NiSe$_5$ monolayer from the low-temperature monoclinic phase. The monolayer is stable and behaves as a normal narrow-gap semiconductor with neither spontaneous excitons nor non-trivial topology. Despite the quasi-particle and optical gaps of only 266 and 200 meV, respectively, its optically-active exciton has a binding energy up to 66 meV and can exist at room temperature. This makes it valuable for applications in infrared photodetection, especially its inherent in-plane anisotropy adds to its value in polarization sensing. It is also found that the inclusion of spin-orbit coupling is theoretically necessary to properly elucidate the optical and excitonic properties of monolayer.

Non-reciprocal hopping induces a synthetic magnetic flux which leads to the non-Hermitian Aharonov-Bohm effect. Since non-Hermitian Hamiltonians possess both real and imaginary eigenvalues, this effect allows the observation of real and imaginary persistent currents in a ring threaded by the synthetic flux~\cite{nrh8}. Motivated by this, we investigate the behavior of persistent currents in a disordered Hatano-Nelson ring with anti-Hermitian intradimer hopping. The disorder is diagonal and we explore three distinct models, namely the Aubry-Andr\'{e}-Harper model, the Fibonacci model, both representing correlated disorder, and an uncorrelated (random) model. We conduct a detailed analysis of the energy spectrum and examine the real and imaginary parts of the persistent current under various conditions such as different ring sizes and filling factors. Interestingly, we find that real and imaginary persistent currents exhibit amplification in the presence of correlated disorder. This amplification is also observed in certain individual random configurations but vanishes after configuration averaging. Additionally, we observe both diamagnetic and paramagnetic responses in the current behavior and investigate aspects of persistent currents in the absence of disorder that have not been previously explored. Interestingly, we find that the intradimer bonds host only imaginary currents, while the interdimer bonds carry only real currents.

Excitonic insulator remains elusive and there has been a lack of reliable identification methods. In this work, we demonstrate the promise of topological excitonic insulators for identification due to their unique bulk-edge correspondence, as illustrated by the LiFe$X$ ($X$ = S, Se, and Te) family. First-principles Bethe-Salpeter equation calculations reveal excitonic instabilities in these spin-orbit coupling quantum anomalous Hall insulators. Effective Hamiltonian analyses indicate that spontaneous exciton condensation does not disrupt the gapless edge state but reconstructs the bulk-gap to be almost independent of the spin-orbit coupling strength. This change in the bulk-edge correspondence can be experimentally inspected by angle-resolved photoelectron spectroscopy or electron compressibility measurements, providing observational evidence for the identification of topological excitonic insulators. Moreover, exciton condensation raises the critical temperature of the topological nontrivial phase above room temperature.

Nonreciprocity of supercurrents may exist when both spatial inversion and time-reversal symmetries are broken, leading to the supercurrent diode effect (SDE). The spatial inversion symmetry may be broken by chiral structures in nanotubes where the SDE is expected when a magnetic flux passes through the tube. While such an effect has been predicted based on a phenomenological theory, a microscopic and quantitative study with a concrete lattice model is missing. Here, we investigate the SDE in chiral nanotubes made of carbon and those made of transition metal dichalcogenides (TMD) with tight-binding models. We obtain the SDE efficiency as a function of the nanotube radius, the chiral angle, the magnetic flux, the temperature, the chemical potential, etc., and find that sign flipping happens in various parameter dependencies. In TMD nanotubes, the SDEs with and without the spin-orbit coupling are compared. We also simulate CNTs made from square lattice materials for comparison and discuss the effects of strains. Besides qualitative consistency with previous phenomenological theory, new features are found and the microscopic origins are clarified.

We analyze the French housing market prices in the period 1970-2022, with high-resolution data from 2018 to 2022. The spatial correlation of the observed price field exhibits logarithmic decay characteristic of the two-dimensional random diffusion equation -- local interactions may create long-range correlations. We introduce a stylized model, used in the past to model spatial regularities in voting patterns, that accounts for both spatial and temporal correlations with reasonable values of parameters. Our analysis reveals that price shocks are persistent in time and their amplitude is strongly heterogeneous in space. Our study confirms and quantifies the diffusive nature of housing prices that was anticipated long ago (Clapp et al. 1994, Pollakowski et al. 1997), albeit on much restricted, local data sets.

The low frequency vibrational anomaly known as Boson peak (BP) have been studied extensively in various disordered systems, however its origin and theoretical description are still under debate. In this work, as one of the simplest model for describing vibrational properties in disordered systems, inhomogeneous elastic wave equation, is solved in real space without using perturbative approach as previous works. In real space solution, the BP associated flat dispersion relation can be obtained, localized vibration in exponential decay in soft spot can be observed, and the fluctuation length of shear modulus dependent BP frequency is also confirmed. These features have been reported in recent progresses but missed within perturbative approach. This work unify divergent and controversial conclusions of BP within a simple model of fluctuating shear modulus under clear visualization.

A magnetic impurity in a BCS superconductor induces the formation of a Shiba state and drives a local quantum phase transition. We generalize this concept to a one-dimensional superconductor with fractionalized excitations, where the dominant instability is superconducting. In this framework, conduction electrons fractionalize into gapless charge and gapped spin excitations. We show that magnetic impurity interacts exclusively with the spin degrees of freedom and induces a quantum phase transition. Furthermore, charge excitations influence dynamical observables, giving rise to the phenomenon we term the fractionalized Shiba state. At zero temperature, the tunneling spectrum exhibits universal power-law scaling with an exponent of $-1/2$ at half filling, stemming from the gapless charge modes that form a standard Luttinger liquid. Extending this analysis to finite temperatures reveals that the spectral features retain universal behavior at the critical point.

In this study, we propose a data-driven, deep-learning-based Machine-Learning Symmetry Discovery (MLSD) algorithm to automate the discovery of continuous Lie group symmetries in classical mechanical systems from their time-evolution trajectory data. MLSD uses neural networks (NNs) to predict conserved physical quantities that implement symmetry transformations of the phase space coordinates. After training, MLSD is able to identify the Lie algebra, particularly non-abelian ones, as indicated by the Lie algebra structure coefficients. To demonstrate the effectiveness of the MLSD method, we applied it to simulated data from the classical three-dimensional Kepler problem and the harmonic oscillator. The results show that the algorithm successfully identified the hidden symmetry groups of both systems.

Magnon Bose-Einstein condensates in ferromagnetic insulators has been a field of much interest, while condensation in anti-ferromagnetic systems are yet to be explored in detail. We analyze the stability of condensed chiral magnons in two antiferromagnetic insulators: an easy-axis system and a biaxial system. We show that two-component magnon condensation and inter-magnon interactions are essential to create metastable magnon condensation. The uniaxial system with a Rashba-type DMI interaction supports two condensate populations at finite wavevectors. The condensation state is stable only when the distribution of magnons between the two populations is symmetric. On the other hand, in the biaxial system without DMI interaction we predict that the magnons condensate will not be stabilized. The results indicate that the lack of stability is a general feature of single-component quasiparticle condensates.

Interacting particles diffusing in single-file is a fundamental model of transport in narrow channels where particles cannot bypass each other. An important result has been obtained by Kollmann for the mean square displacement of a tracer for any such single-file model. However, since then, no general result has been obtained in the important case where the particles are driven by an external field. Here, we fill this gap and determine the fluctuations and the skewness of the tracer's position for any driven diffusive system. In addition, we also consider a variety of important observables such as the integrated current, the response of the system to the perturbation induced by the displacement of the tracer, and the correlations between several tracers. Furthermore, we also unveil fundamental relations underlying the out-of-equilibrium dynamics of driven diffusive systems. This work constitutes a first step toward a full description of driven one-dimensional systems of interacting particles.

Dynamic resistance occurs in a superconducting tape carrying a dc transport current while being exposed to an alternating magnetic field. This effect is caused by flux movements interacting with the transport current. The dynamic resistance is already applied in many superconducting applications, for example superconducting flux pumps or persistent current switches. The resistance is highly dependent on the magnetic field and the frequency the superconductor is subjected to and its properties. When the dynamic resistance exceeds a certain value and thus enters the magnitude of the resistances of the normal conducting layers of the HTS tape, these normal conducting layers play a significant role in the total resistance of the tape. In this paper, modifications were made to the silver stabilizer and the total resistance of the HTS tape has been investigated. The experimental results with frequencies up to 1000 Hz and magnetic field up to 277 mT show significant increases in resistance. Additionally, a multilayer model based on H-formulation is presented to calculate the losses of the superconductor. The results also show significant heating due to the losses and therefore a temperature rise, which effects the measured total resistance. These results can be further used for applications where high switchable resistances are required with zero dc resistance when the magnet is turned off.

We study fractional Laplace motion (FLM) obtained from subordination of fractional Brownian motion to a gamma process, in the presence of an external drift that acts on the composite process or of an internal drift acting solely on the parental process. We derive the statistical properties of this FLM process and find that the external drift does not influence the mean-squared displacement (MSD), whereas the internal drift leads to normal diffusion, dominating at long times in the subdiffusive Hurst exponent regime. We also investigate the intricate properties of the probability density function (PDF), demonstrating that it possesses a central Gaussian region, whose expansion in time is influenced by FBM's Hurst exponent. Outside of this region the PDF follows a non-Gaussian pattern. The kurtosis of this FLM process converges toward the Gaussian limit at long times insensitive to the extreme non-Gaussian tails. Additionally, in the presence of the external drift, the PDF remains symmetric and centered at $x=vt$. In contrast, for the internal drift this symmetry is broken. The results of our computer simulations are fully consistent with the theoretical predictions. The FLM model is suitable for describing stochastic processes with a non-Gaussian PDF and long-ranged correlations of the motion.

We analyzed mathematically a model describing flux jumps in superconductivity in a 1D configuration. Three effects occur from fastest to slowest: Joule heating, magnetic relaxation and temperature diffusion. Adimensionalising the equations showed that magnetic field fronts penetrate the material as inhomogeneous Burgers fronts. An additional global term pushes the magnetic field and is responsible for flux jumps. We considered a medium temperature for which the heat capacity of a sample can be taken as a constant and a low temperature where heat capacity depends on temperature causing a nonlinear temperature evolution. As expected, we found that flux jumps occur mostly at low temperature. To understand flux trapping, we examined external magnetic field pulses of different amplitudes and duration. We found that flux trapping is maximal for medium amplitudes and low temperatures.

The development of laser science and technology have stimulated the study of condensed matter physics, especially, dynamical or non-equilibrium nature in solids. The laser technique in terahertz (THz) regime, whose photon energy is comparable to those of typical collective modes in solids such as magnetic excitations, phonons, etc., has remarkably proceeded in the last decade. Theoretical tools for non-equilibrium states have also progressed. Thanks to these backgrounds, magneto-optics, especially, the study of controlling magnetism with laser, now enters a new stage. For such controls, Floquet engineering is a key concept, which means the method of controlling static properties of targets with high-frequency external fields like laser. I review the theoretical foundation of Floquet engineering and its application to magnetic insulators. Basic magnetic quantities such as magnetization, spin chirality, and spin current are shown to be controlled with intense THz laser or wave.

The dominance of short-range spin Ising coupling in a-RuCl3 within a temperature range from 120 K to 7 K establishes it as a highly promising candidate for the Kitaev spin liquid. Here, employing scanning tunneling microscopy/spectroscopy measurements, we present our observations on the temperature-dependent dI/dV spectra of monolayer a-RuCl3 directly grown on graphite. We observe a pronounced softening of the Mott gap upon warming the temperature from liquid nitrogen temperature to approximately 120 K, characterized by the shift of charge states in the edges of Hubbard bands toward the Mott gap. This transition temperature corresponds to the crossover from the Kitaev paramagnetic Mott insulator to the conventional paramagnetic Mott insulator of a-RuCl3. The same transition can also be seen in bulk form of a-RuCl3. Our findings suggest that the recombination of spinons and chargons during the disappearance of Kitaev spin coupling has significantly impacted the charge dynamics in the Mott insulator, even without altering the ratio between Coulomb repulsion and bandwidth. The results imply that a-RuCl3 could serve as an ideal platform for investigating the Mott physics across various spin states, encompassing antiferromagnetic-, spin-frustrated- and paramagnetic-phases.

The energy level statistics of uniform random graphs are studied, by treating the graphs as random tight-binding lattices. The inherent random geometry of the graphs and their dynamical spatial dimensionality, leads to various quantum chaotic and localized phases and transitions between them. Essentially the random geometry acts as disorder, whose strength is characterized by the ratio of edges over vertices R in the graphs. For dense graphs, with large ratio R, the spacing between successive energy levels follows the Wigner-Dyson distribution, leading to a quantum chaotic behavior and a metallic phase, characterized by level repulsion. For ratios near R=0.5, where a large dominating component in the graph appears, the level spacing follows the Poisson distribution with level crossings and a localized phase for the respective wavefunctions lying on the graph. For intermediate ratios R we observe a phase transition between the quantum chaotic and localized phases characterized by a semi-Poisson distribution. The values R of the critical regime where the phase transition occurs depend on the energy of the system. Our analysis shows that physical systems with random geometry, for example ones with a fluctuating/dynamical spatial dimension, contain novel universal phase transition properties, similar to those occuring in more traditional phase transitions based on symmetry breaking mechanisms, whose universal properties are strongly determined by the dimensionality of the system.

Recently, the simulation of moir\'e physics using cold atom platforms has gained significant attention. These platforms provide an opportunity to explore novel aspects of moir\'e physics that go beyond the limits of traditional condensed matter systems. Building on recent experimental advancements in creating twisted bilayer spin-dependent optical lattices for pseudospin-1/2 Bose gases, we extend this concept to a trilayer optical lattice for spin-1 Bose gases. Unlike conventional moir\'e patterns, which are typically induced by interlayer tunneling or interspin coupling, the moir\'e pattern in this trilayer system arises from inter-species atomic interactions. We investigate the ground state of Bose-Einstein condensates loaded in this spin-1 twisted optical lattice under both ferromagnetic and antiferromagnetic interactions. We find that the ground state forms a periodic pattern of distinct phases in the homogeneous case, including ferromagnetic, antiferromagnetic, polar, and broken axial symmetry phases. Additionally, by quenching the optical lattice potential strength, we examine the quench dynamics of the system above the ground state and observe the emergence of topological excitations such as vortex pairs. This study provides a pathway for exploring the rich physics of spin-1 twisted optical lattices and expands our understanding of moir\'e systems in synthetic quantum platforms.

The quasi-two-dimensional material Sr$_2$RuO$_4$ has been the focus of extensive experimental and theoretical research, as it is a paradigmatic example of a correlated system that exhibits unconventional superconductivity and intriguing magnetic properties. The interplay between these two effects has sparked significant debates, especially on the strength of the spin excitations. We show that self-consistently incorporating spatial magnetic fluctuations into our theoretical framework significantly reduces the many-body effects in the system. Consistent with experimental observations, this reduction destabilizes the magnetic ordering in Sr$_2$RuO$_4$, which is not found in our calculations in contrast to previous theoretical studies. This resolution of the long-standing discrepancy between theory and experiment is supported by a theoretical calculation of the spin susceptibility that closely matches the experimental results.

Compounds based on Cr have been found to be among the first single-layer magnets. In addition, transition metal dichalcogenides are promising candidates to show long-range ferromagnetic order down to the two-dimensional limit. We use ab initio calculations to provide a description of the various Cr$_x$Se$_{x+1}$ stoichiometries that may occur by analyzing from the bulk materials to the monolayer limit. We study the different structural distortions, including charge density waves that each system can present by analyzing their phonon spectra and dynamic stability. We provide a description of their basic electronic structure and study their magnetic properties, including the magnetocrystalline anisotropy energy. The evolution of all these properties with the dimensionality of the systems is discussed. This intends to be a comprehensive view of the broad family of Cr selenides.

We calculate the magnetic phase diagram of the spin-$1/2$ nearest neighbor XXZ pyrochlore model using the pseudo-Majorana functional renormalization group in the temperature flow formalism. Our phase diagram as a function of temperature and coupling ratio, allowing both longitudinal and transverse couplings to be ferromagnetic and antiferromagnetic, reveals a large non-magnetic regime at low temperatures, which includes the quantum spin ice phase near the antiferromagnetic Ising model, as well as the antiferromagnetic Heisenberg and XY models. We are able to detect magnetic phase transitions via critical finite size scaling down to temperatures two orders of magnitude smaller than the spin interactions, demonstrating the remarkably good performance of our method upon approaching the ground state. Specifically, the low temperature transition from the zero-flux quantum spin ice phase into the transverse ferromagnetic phase shows very good agreement with previous quantum Monte Carlo results. Comparing our findings with classical results, we identify a quantum order-by-disorder effect near the antiferromagnetic XY model. In magnetically disordered regimes, we find characteristic patterns of broadened pinch points in the spin structure factor and investigate their evolution when approaching magnetically ordered phases. We also compute linear responses to lattice symmetry breaking perturbations and identify a possible lattice nematic ground state of the antiferromagnetic XY model.

Multi-component liquid mixtures can be both complex and fascinating, with some systems being amenable to simple experimentation at home, giving valuable insight into fundamental aspects of bulk and interfacial phase behaviour. One particularly interesting mixture is the popular drink ouzo, which has charmed both the general public and scientists by virtue of its ability to display spontaneous emulsification when water is added. When these two clear (and potable) liquids are poured into each other, a single milky-coloured liquid is formed. In previous work [Archer et al., Soft Matter 20, 5889 (2024)], the equilibrium phase-diagram for the stable liquid phases of ouzo was captured via experiment and modelling. Here we consider the case when the two liquid phases also coexist with the vapour phase (i.e. along a line of triple points) and within our model uncover the complex bulk phase behaviour for this simple beverage. As a consequence, this leads to some interesting observations, that also apply more widely, about visualising phase diagrams in ternary systems of this type. We also examine the interfacial behaviour, connecting microscopic density functional theory results with macroscopic (Neumann) predictions for the shape of droplets at interfaces.

Dispersive readout of superconducting qubits is often limited by readout-drive-induced transitions between qubit levels. While there is a growing understanding of such effects in transmon qubits, the case of highly nonlinear fluxonium qubits is more complex. We theoretically analyze measurement-induced state transitions (MIST) during the dispersive readout of a fluxonium qubit. We focus on a new mechanism: a simultaneous transition/excitation involving the qubit and an internal mode of the Josephson junction array in the fluxonium circuit. Using an adiabatic Floquet approach, we show that these new kinds of MIST processes can be relevant when using realistic circuit parameters and relatively low readout drive powers. They also contribute to excess qubit dephasing even after a measurement is complete. In addition to outlining basic mechanisms, we also investigate the dependence of such transitions on the circuit parameters. We find that with a judicious choice of frequency allocations or coupling strengths, these parasitic processes can most likely be avoided.

The dynamical cavity method and its backtracking version provide a powerful approach to studying the properties of dynamical processes on large random graphs. This paper extends these methods to hypergraphs, enabling the analysis of interactions involving more than two variables. We apply them to analyse the $k$-XOR-satisfiability ($k$-XOR-SAT) problem, an important model in theoretical computer science which is closely related to the diluted $p$-spin model from statistical physics. In particular, we examine whether the quench dynamics -- a deterministic, locally greedy process -- can find solutions with only a few violated constraints on $d$-regular $k$-uniform hypergraphs. Our results demonstrate that the methods accurately characterize the attractors of the dynamics. It enables us to compute the energy reached by typical trajectories of the dynamical process in different parameter regimes. We show that these predictions are accurate, including cases where a classical mean-field approach fails.

Strong correlation brings a rich array of emergent phenomena, as well as a daunting challenge to theoretical physics study. In condensed matter physics, the fractional quantum Hall effect is a prominent example of strong correlation, with Landau level mixing being one of the most challenging aspects to address using traditional computational methods. Deep learning real-space neural network wavefunction methods have emerged as promising architectures to describe electron correlations in molecules and materials, but their power has not been fully tested for exotic quantum states. In this work, we employ real-space neural network wavefunction techniques to investigate fractional quantum Hall systems. On both $1/3$ and $2/5$ filling systems, we achieve energies consistently lower than exact diagonalization results which only consider the lowest Landau level. We also demonstrate that the real-space neural network wavefunction can naturally capture the extent of Landau level mixing up to a very high level, overcoming the limitations of traditional methods. Our work underscores the potential of neural networks for future studies of strongly correlated systems and opens new avenues for exploring the rich physics of the fractional quantum Hall effect.

Out-of-equilibrium electron-gas systems exhibit rich physics, which we explore through three problems. First, we study photoemission from metals, traditionally analyzed in the frequency domain. Unexpectedly, the photoemission rate oscillates at high frequencies as it decays, with the oscillation amplitude decaying faster than the average current. Analytical and numerical results reveal this behavior arises from interference between two excitation processes: one decaying via the Doniach-Sunjic power law and the other following the faster Nozi\`eres-De Dominicis law. XPS experiments targeting this feature could identify its frequency-domain counterpart. Second, we examine adiabaticity in an electron gas subject to a localized potential ramping up at a constant rate. Analytical and numerical findings map the parameter space where the system behaves adiabatically. Contrary to the Quantum Adiabatic Criterion, which links adiabaticity to slow ramp-up rates, we show that the number of energy scales involved in screening the potential dictates non-adiabaticity. Lastly, we investigate the collision of a neutral hydrogen atom with a copper surface. Electron transfer ionizes the H atom, activating an image-charge potential that pulls the ion toward the surface. Using a spinless model, we numerically track the atomic wave packets evolution and compute the sticking coefficient, the probability the atom remains near the surface. The coefficient peaks near 300 meV, balancing non-adiabatic contributions, which increase with energy, and the traversal time through the interaction region. Numerical results align semi-quantitatively with experimental data.

The semiconductiong ${\alpha'}$-borophene nanoribbon (${\alpha'}$-BNR) due to its incredible properties such as high stability and great mobility of carriers demostrates high-efficiency in thermoelectric devices. These properties enable us to produce the spin current by a temperature gradient with lower energy consumption technology. In this research, the spin-dependent Seebeck effects are studied in a zigzag ${\alpha'}$-borophene nanoribbon with two leads magnetized by ferromagnetic (FM) insulators. The thermoelectric calculations are performed for a ${\alpha'}$-BNR FM/Normal/FM junction using the tight-binding (TB) formalism in combination with the non-equilibrium Green's function method (NEGF). A pure spin-dependent current due to the breaking of the electron-hole symmetry is induced in the system by a temperature gradient so that it can act as a spin-Seebeck diode. Moreover, the negative differential spin-Seebeck effect can be observed in this device dueto the compensation of thermal spin in the spin-dependent currents. Finally, we have studied the effect of temperature on the charge and spin power factors in ${\alpha'}$-BNR. A significant decline in power factor is primarily arises from a reduction in the magnitude of thermopower near the Fermi level. Our findings demonstrate that the ${\alpha'}$-BNR has a higher power factor compared to its rivals e.g., graphene and silicene. This is attributed to the semiconducting nature and high asymmetry between electrons and holes in the ${\alpha'}$-BNR. The exceptional features of ${\alpha'}$-BNR makes it a very suitable choice for using in thermoelectric devices.

We study the evolution of a system of many point particles initially concentrated in a small region in $d$ dimensions. Particles undergo overdamped motion caused by pairwise interactions through the long-ranged repulsive $r^{-s}$ potential; each particle is also subject to Brownian noise. When $s

Phase crystals are a class of non-uniform superconducting ground states characterized by spontaneous phase gradients of the superconducting order parameter. These phase gradients non-locally drive periodic currents and magnetic fields, thus breaking both time-reversal symmetry and continuous translational symmetry. The phase crystal instability is generally triggered by negative and inhomogeneous superfluid stiffness. Several scenarios have been identified that can realize phase crystals, especially flat bands at specific edges of unconventional nodal superconductors. Motivated by omnipresent disorder in all materials, we employ the ${t}$-matrix approach within the quasiclassical theory of superconductivity to study the emergence of phase crystals at edges of a nodal $d$-wave superconductor. We quantify the full phase diagram as a function of the impurity scattering energy and the temperature, with full self-consistency in the impurity self energies, the superconducting order parameter, and the vector potential. We find that the phase crystal survives even up to $\sim 40-50\%$ of the superconducting critical impurity strength in both the Born and unitary scattering limits. Finally, we show how mesoscopic finite-size effects induce a competition with a state still breaking time-reversal symmetry but with translationally invariant edge currents.

We define a measurable spin for the edge of a lowest Landau level and incompressible fractional quantum Hall state in the presence of an Abelian or non-Abelian bulk quasiparticle. We show that this quantity takes a fractional value inherited from the fractional spin of the bulk quasiparticle. We present a geometric picture that does not rely on global symmetries of the wavefunction but is able to treat quasiparticles and edges with different shapes. We study finite-size many-body wavefunctions on the cylinder with circular quasiparticles and straight edges. Our results are supported by matrix-product-state calculations for the Laughlin and the k=3 Read-Rezayi states.

Enhancing the dimensionless figure of merit zT is central to developing better thermoelectric materials and advancing thermoelectric generation technology. However, the intrinsic interdependence between electrical conductivity, the Seebeck coefficient, and thermal conductivity presents a significant challenge. Over time, various strategies have emerged, but the literature remains difficult to navigate due to its widespread distribution across numerous sources. This short review highlights the key approaches to improving zT, offering a clear and concise guide to help researchers understand the major ideas and breakthroughs in the field.

We study the $k=3$ Read-Rezayi quantum Hall state by means of a purely bosonic matrix product state formulation, which is described in detail. We calculate the density profiles in the presence of bulk quasi-holes of six different types: one for each $\mathbb{Z}_3$ parafermion sector. From the density profiles, we calculate the (local) spins of these quasi-holes. By employing a spin-statistics relation, we obtain the exchange statistics parameters. Our results, which are entirely based on local properties of the quasi-holes, corroborate previous results obtained by explicitly braiding quasi-holes, showing that the exchange statistics can be read off from the monodromy properties of the wave functions, i.e., that the associated Berry phase vanishes. We also discuss the entanglement spectrum, to show that our bosonic matrix product state formulation correctly captures the $\mathbb{Z}_3$ parafermionic structure of the $k=3$ Read-Rezayi states.

We propose a novel and systematic recurrence method for the energy spectra of non-Hermitian systems under open boundary conditions based on the recurrence relations of their characteristic polynomials. Our formalism exhibits better accuracy and performance on multi-band non-Hermitian systems than numerical diagonalization or the non-Bloch band theory. It also provides a targeted and efficient formulation for the non-Hermitian edge spectra. As demonstrations, we derive general expressions for both the bulk and edge spectra of multi-band non-Hermitian models with nearest-neighbor hopping and under open boundary conditions, such as the non-Hermitian Su-Schrieffer-Heeger and Rice-Mele models and the non-Hermitian Hofstadter butterfly - 2D lattice models in the presence of non-reciprocity and perpendicular magnetic fields, which is only made possible by the significantly lower complexity of the recurrence method. In addition, we use the recurrence method to study non-Hermitian edge physics, including the size-parity effect and the stability of the topological edge modes against boundary perturbations. Our recurrence method offers a novel and favorable formalism to the intriguing physics of non-Hermitian systems under open boundary conditions.

The enhancement of Neel temperature ($T_N$) of low-$T_{N}$ antiferromagnets in antiferromagnetic bilayers AF1/AF2, where the $T_N$ of AF1 is larger than AF2 (for example enhancement of $T_{N}$ of CoO in CoO/NiO or FeO in FeO/CoO), is a subject of considerable interest. One essential question needs to be answered in these bilayers: is the interfacial coupling a short-range one or long-range that mediates the effect of the AF1 layers on the magnetic properties of AF2 layer? To understand the systematics of the magnetic coupling across the interface, we investigate the plane-resolved magnetotransport properties of antiferromagnetic bilayers using an electron-hole symmetric one-band Hubbard model at half-filling, employing a semi-classical Monte Carlo method. In our model Hamiltonian calculations, we set Coulomb repulsion $U_{1} = 8$ to mimic high-$T_{N}$ AF1 layer, whereas we use $U_{2}$ = $2\times U_{1}$ to mimic the low-$T_{N}$ AF2 layer. Our calculations show that the $T_{N}$ of the low-$T_{N}$ antiferromagnet enhances substantially when it's thickness is small, similar to experiments, giving rise to single magnetic transition temperature of the bilayer system. These findings are well supported by a single peak in temperature-dependent specific heat. However, for larger thicknesses, the $T_{N}$ of the low-$T_{N}$ antiferromagnet approaches towards its bulk value and constituent antiferromagnetic layers align antiferromagnetically at two separate temperatures and two maxima are observed in specific heat data. Our calculations also show that the delocalization of moments is more or less confined near the interface indicating the short-ranged nature of the proximity effect. Our obtained results are consistent with the experimental observations. A detailed discussion of the modifications that will occur if we use $U_{1} = 8$ and $U_{2}$ = $0.5\times U_{1}$ will also be addressed.

Impurities can strongly influence dislocation behavior and thus impact plasticity. Quantifying dislocation-impurity interactions in $\alpha$-Fe from ab initio across a wide temperature range is challenging due to paramagnetism at elevated temperatures. In this work, we investigate the energy profiles and segregation behavior of various 3d elements - V, Cr, Mn, Cu, Ni, and Co - in and around $1/2\langle111\rangle$ screw dislocations in $\alpha$-Fe in ferromagnetic and paramagnetic state with the latter being modeled through both the disordered local moment model and a spin-wave approach using ab initio methods. Our findings reveal that (1) magnetic effects are large compared to elastic size effects, and (2) dislocation-impurity interactions are dependent on the magnetic state of the matrix and thermal lattice expansion. In particular, Cu changes from core-attractive in the ferromagnetic state to repulsive in the paramagnetic state.

Photocurrent-induced harmonics appear in gases and solids due to tunnel ionization of electrons in strong fields and subsequent acceleration. In contrast to three-step harmonic emission, no return to the parent ions is necessary. Here we show that the same mechanism produces harmonics in metallic nanostructures in strong fields. Furthermore, we demonstrate how strong local field gradient, appearing as a consequence of the field enhancement, affects photocurrent-induced harmonics. This influence can shed light at the state of electron as it appears in the continuum, in particular, to its initial velocity.

The experimental measurement of collective charge fluctuations in metals and superconductors is a preferential tool to benchmark fundamental interactions in solids. Recent experiments in multicomponent systems, from superconducting layered cuprates to multiband metals, highlighted striking effects due to the interplay between different degrees of freedom. In this paper we provide a physical explanation for the existence of a "ghost" Josephson plasmon in bilayer superconductors, layered systems with two layers per unit cells that interact with two different Josephson couplings. We show that one of the two plasmons that emerge after the breaking of the translational symmetry along the out-of-plane direction is connected to counterflowing current fluctuations polarized perpendicularly to the planes. This effect makes it a staggered mode that is virtually transverse at small out-of-plane momenta qc, explaining why it is hidden in the density response at small qc. Our work offers an additional perspective on the understanding of collective excitations in systems with multiple intertwined degrees of freedom.

Cs$_2$AgBiBr$_6$ shows promise for solution-processable optoelectronics, such as photovoltaics, photocatalysis and X-ray detection. However, various spectroscopic studies report rapid charge carrier mobility loss in the first picosecond after photoexcitation, limiting carrier collection efficiencies. The origin of this rapid mobility loss is still unclear. Here, we directly compare hot excitation with excitation over the indirect fundamental bandgap, using transient absorption and THz spectroscopy on the same Cs$_2$AgBiBr$_6$ thin film sample. From transient absorption spectroscopy, we find that hot carriers cool towards the band-edges with a cooling rate of 0.58 ps$^{-1}$, which coincides with the observed mobility loss rate from THz spectroscopy. Hence, our study establishes a direct link between the hot carrier cooling and ultrafast mobility loss on the picosecond timescale.

The pseudogap in high-temperature superconducting cuprates is an exotic state of matter, displaying emerging Fermi arcs and a momentum-selective suppression of states upon cooling. We show how these phenomena are originating in the three-band Emery model by performing cutting-edge dynamical vertex approximation calculations for its normal state. For the hole-doped parent compound our results demonstrate the formation of a pseudogap due to short-ranged commensurate antiferromagnetic fluctuations. At larger doping values, progressively, incommensurate correlations and a metallic regime appear. Our results are in qualitative agreement with the normal state of cuprates, and, hence, represent a crucial step towards the uniform description of their phase diagrams within a single theoretical framework.

We simulate high-pressure hydrogen in its liquid phase close to molecular dissociation using a machine-learned interatomic potential. The model is trained with density functional theory (DFT) forces and energies, with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional. We show that an accurate NequIP model, an E(3)-equivariant neural network potential, accurately reproduces the phase transition present in PBE. Moreover, the computational efficiency of this model allows for substantially longer molecular dynamics trajectories, enabling us to perform a finite-size scaling (FSS) analysis to distinguish between a crossover and a true first-order phase transition. We locate the critical point of this transition, the liquid-liquid phase transition (LLPT), at 1200-1300 K and 155-160 GPa, a temperature lower than most previous estimates and close to the melting transition.

A new axion-haloscope is setup at the Johannes Gutenberg university of Mainz, named the Supax (a SUPerconducting AXion search) experiment. This setup is used to characterize the behaviour of a NbN coated superconducting cavity in a 2.5T strong magnetic field, at a resonance frequency of 8.4GHz. We observe an increasing surface resistance with increasing magnetic field, leading to a decreasing quality factor. The behaviour is similar to that of previously studied cavities using Nb3Tn.

Recent advancements have demonstrated that fully Eulerian methods can effectively model frictionless contact between deformable solids. Unlike traditional Lagrangian approaches, which require contact detection and resolution algorithms, the Eulerian framework utilizes a single, fixed spatial mesh combined with a diffuse interface phase-field approach, simplifying contact resolution significantly. Moreover, the Eulerian method is well-suited for developing a unified framework to handle multiphysical systems involving growing bodies that interact with a constraining medium. In this work, we extend our previous methodology to incorporate frictional contact. By leveraging the intersection of the phase fields of multiple bodies, we define normal and tangential penalty force fields, which are incorporated into the linear momentum equations to capture frictional interactions. This formulation allows independent motion of each body using distinct velocity fields, coupled solely through interfacial forces arising from contact and friction. We thoroughly validate the proposed approach through several numerical examples. The method is shown to handle large sliding effortlessly, accurately capture the stick-slip transition, and preserve history-dependent energy dissipation, offering a solution for modeling frictional contact in Eulerian models.

In socioeconomic systems, nonequilibrium dynamics naturally stem from the generically non-reciprocal interactions between self-interested agents, whereas equilibrium descriptions often only apply to scenarios where individuals act with the common good in mind. We bridge these two contrasting paradigms by studying a Sakoda-Schelling occupation model with both individualistic and altruistic agents, who, in isolation, follow nonequilibrium and equilibrium dynamics respectively. We investigate how the relative fraction of these two populations impacts the behavior of the system. In particular, we find that when fluctuations in the agents' decision-making process are small (high rationality), a very moderate amount of altruistic agents mitigates the sub-optimal concentration of individualists in dense clusters. In the regime where fluctuations carry more weight (low rationality), on the other hand, altruism progressively allows the agents to coordinate in a way that is significantly more robust, which we understand by reducing the model to a single effective population studied through the lens of active matter physics. We highlight that localizing the altruistic intervention at the right point in space may be paramount for its effectiveness.

Nanoconfined water plays an indispensable role in various phenomena in biology, chemistry, and engineering. It exhibits many abnormal properties compared to bulk water, especially under strong confinement. However, the origin of those anomalies is still elusive due to the lack of structural information on hydrogen-bonding networks. Considering the inhomogeneity of the nanocavity and the tiny amount of water molecules, conventional optical spectroscopies and nuclear magnetic resonance (NMR) fail to realize the structure analysis of nanoconfined water. Here, we addressed this issue by combining scanning probe microscopy (SPM) with advanced quantum sensing(QS) based on an atomic-size quantum sensor like nitrogen-vacancy (NV) center in diamond, which can apply the nanoscale-NMR for characterizing both the dynamics and structure of confined water at ambient conditions. We built a two-dimensional (2D) nanoconfined water system with a hexagonal-boron nitride (hBN) flake and a hydrophilic diamond surface. By using the SPM tip to measure the confinement size precisely, we observed a critical confinement size of ~2 nm, below which the water diffusion was significantly suppressed and the hydrogen-bonding network of water showed an ordered structure. Meanwhile, molecular dynamics (MD) simulation revealed a solid-like water contact layer on the diamond surface under strong confinement, which also reproduced the measured nanoscale-NMR spectra and confirmed the liquid-solid phase transition observed in the experiments. Notably, with this new SPM-QS platform, our results showed a promising way to elucidate the abnormal properties of nanoconfined water in future applications.

Exciton mediated superconductor is a fascinating quantum phase of matter that occurs when excitons become the dominant excitation in materials, which is also very promising for high temperature superconductor. However, there is no experimental report of exciton mediated superconductivity. Herein, we realize exciton mediated superconductivity from exciton insulator, where the onset transition temperature can reach larger than 200 K. More profoundly, Bose-Einstein condensation (BEC) of exciton can facilitate the formation of exciton insulator and a transition happened from extremely high resistivity of 107 {\Omega} at 153.5 K to 100 {\Omega} at 125 K, indicating a superconducting transition. The resistance of exciton mediated superconductivity can not be absolutely reach zero possibly as a result of drag effect between electrons/holes and excitons. We reveal one rule for exciton mediated superconductivity is that the resistivity is an inverse linear function of the current through the BEC superfluid state, which should be ascribed to the Andreev-Bashkin effect, which reflects the coupling between the BEC state of exciton and Cooper pairs mediated by excitons. Furthermore, a record transition temperature above 200 K has been found for one superconducting sample, which shows the Josephson oscillation dominated by a pendulum-like equation caused by the quantum coupling between superconductor and BEC superfluid of exciton.

We address the challenge of incorporating non-Markovian electronic friction effects in quantum-mechanical approximations of dynamical observables. A generalized Langevin equation (GLE) is formulated for ring-polymer molecular dynamics (RPMD) rate calculations, which combines electronic friction with a description of nuclear quantum effects (NQEs) for adsorbates on metal surfaces. An efficient propagation algorithm is introduced that captures both the spatial dependence of friction strength and non-Markovian frictional memory. This framework is applied to a model of hydrogen diffusing on Cu(111) derived from ab initio density functional theory (DFT) calculations, revealing significant alterations in rate constants and tunnelling crossover temperatures due to non-Markovian effects. Our findings explain why previous classical molecular dynamics simulations with Markovian friction showed unexpectedly good agreement with experiment, highlighting the critical role of non-Markovian effects in first-principles atomistic simulations.

Brownian motion is essential for describing diffusion in systems ranging from simple to complex liquids. Unlike simple liquids, which consist of only a solvent, complex liquids, such as colloidal suspensions or the cytoplasm of a cell, are mixtures of various constituents with different shapes and sizes. Describing Brownian motion in such multiscale systems is extremely challenging because direct and many-body hydrodynamic interactions (and their interplay) play a pivotal role. Diffusion of small particles is mainly governed by a low viscous character of the solution, whereas large particles experience a highly viscous flow of the complex liquid on the macro scale. A quantity that encodes hydrodynamics on both length scales is the wave-vector-dependent viscosity. Assuming this quantity to be known -- in contrast to most studies in which the solvent shear viscosity is given -- provides a new perspective on studying the diffusivity of a tracer, especially in situations where the tracer size can vary by several orders of magnitude. Here, we start systematic studies of exact formal microscopic expressions for the short- and long-time self-diffusion coefficients of a single probe particle in a complex liquid in terms of short-ranged hydrodynamic response kernels. We study Brownian motion as a function of the probe size, contrasting most theories that focus on self-diffusion as a function of the crowder volume fraction. We discuss the limits of small and large probe sizes for various levels of approximations in our theory, and discuss the current successes and shortcomings of our approach.

In this work we study self-consistent solutions in one-dimensional lattice models obtained via many-body perturbation theory. The Dyson equation is solved in a fully self-consistent manner via the algorithmic inversion method based on the sum-over-pole representation (AIM-SOP) of dynamical operators. We start by validating our self-consistent AIM-SOP implementation by taking as test case the one-dimensional Hubbard model. We then move to the study of antiferromagnetic and charge density wave solutions in one-dimensional lattice models, taking into account a long-range Coulomb interaction between the electrons. Complementary, by solving the Sham-Schl\"uter equation, we can compute the non-interacting Green's function reproducing the same charge density of the interacting system. In turn, this allows for the evaluation of the derivative discontinuity in the Kohn-Sham potential, which gives a measure of how the Kohn-Sham gap approximates the many-body fundamental gap of these systems.

Categorical symmetries have recently been shown to generalize the classification of phases of matter, significantly broadening the traditional Landau paradigm. To test these predictions, we propose a simple spin chain model that encompasses all gapped phases and second-order phase transitions governed by the categorical symmetry $\mathsf{Rep}(D_8)$. This model not only captures the essential features of non-invertible phases but is also straightforward enough to enable practical realization. Specifically, we outline an implementation using neutral atoms trapped in optical tweezer arrays. Employing a dual-species setup and Rydberg blockade, we propose a digital simulation approach that can efficiently implement the many-body evolution in several nontrivial quantum phases.

We derive the nonequilibrium conductance matrix for open stationary Chemical Reaction Networks (CRNs) described by a deterministic mass action kinetic equation. As an illustration, we determine the nonequilibrium conductance matrix of a CRN made of two sub-networks, called chemical modules, in two different ways: First by computing the nonequilibrium conductances of the modules that are then serially connected. Second by computing directly the nonequilibrium conductance of the CRN directly. The two approaches coincide, as expected from our theory of thermodynamic circuits. We end by discussing the advantages of splitting a CRN into smaller chemical modules.

We determine the current-force characteristics of the serial (respectively parallel) association of two ThermoElectric Converters (TEC) using the laws of resistance (respectively conductance) matrix addition. Each TEC is modeled by a non-equilibrium conductance/resistance matrix describing the current-force characteristics of the TEC in stationary non-equilibrium. For TECs in series, we investigate the continuity of the potentials (and their derivatives) at their interfaces when thermoelectric coefficients are equal or not. We also study the current-dependent boundary conditions (for each sub-device) that significantly modify the conversion process. For TECs in parallel, we show that our result is compatible with the previously mentioned internal current loops even in open circuit boundary conditions.

An optical flux lattice is a set of light beams that couple different internal states of an atom, thereby producing topological energy bands. Here we present a configuration in which the atoms exhibit a dark state, i.e. an internal state that is not coupled to the light. At large light intensity, the low-energy dynamics is restricted to the dark state, leading to an effective continuum model with a Landau-level-like structure. This structure is dramatically different from that of usual topological optical lattices, which lead to discrete models in the tight-binding limit. The proposed system is essentially immune to heating due to photon scattering, making it a highly promising way to emulate the integer or fractional quantum Hall effect.

Nuclear magnetic resonance (NMR) is a powerful spectroscopic technique that is sensitive to the local atomic structure of matter. Computational predictions of NMR parameters can help to interpret experimental data and validate structural models, and machine learning (ML) has emerged as an efficient route to making such predictions. Here, we systematically study graph-neural-network approaches to representing and learning tensor quantities for solid-state NMR -- specifically, the anisotropic magnetic shielding and the electric field gradient. We assess how the numerical accuracy of different ML models translates into prediction quality for experimentally relevant NMR properties: chemical shifts, quadrupolar coupling constants, tensor orientations, and even static 1D spectra. We apply these ML models to a structurally diverse dataset of amorphous SiO$_2$ configurations, spanning a wide range of density and local order, to larger configurations beyond the reach of traditional first-principles methods, and to the dynamics of the $\alpha\unicode{x2013}\beta$ inversion in cristobalite. Our work marks a step toward streamlining ML-driven NMR predictions for both static and dynamic behavior of complex materials, and toward bridging the gap between first-principles modeling and real-world experimental data.

In this work, we employed the Ising model to identify phase transitions in a magnetic system where the degree distribution of the network follows a power-law and the connections are assortatively mixed. In the Ising model, the spins assume only two values, $\sigma = \pm 1$, and interact through ferromagnetic coupling $J$. The network is characterized by four variable parameters: $\alpha$ denotes the degree distribution exponent, the minimum degree $k_0$, the maximum degree $k_m$, and the $p_r$ represents the assortativity or disassortativity of the network. To investigate the effect of degree correlations on the critical behavior of the system, we fix $k_0=4$, $k_m=10$, and $\alpha=1$, and vary $p_r$ to obtain an assortative mixing of edges. As result, we have calculated the phase transition points of the system, and the critical exponents related to magnetization $\beta$, magnetic susceptibility $\gamma$, and the correlation length $\nu$.

The experimental demonstration of electric skyrmion bubbles and the recent prediction of their Brownian motion have brought topological ferroelectrics close to their magnetic counterparts. Electric bubbles (e-bubbles) could potentially be leveraged in applications for which magnetic skyrmions have been proposed (e.g., neuromorphic computing). Yet, we still lack a strategy to create currents of e-bubbles. Here, using predictive atomistic simulations, we illustrate two approaches to induce e-bubble currents by application of suitable electric fields, static or dynamic. We focus on regimes where e-bubbles display spontaneous diffusion, which allows us to generate a current by simply biasing their Brownian motion. Our calculations indicate that e-bubble velocities over 25 m/s can be achieved at room temperature, suggesting that these electric quasiparticles could rival the speeds of magnetic skyrmions upon further optimization.

We present an extension of Landau's theory of phase transitions by incorporating the topology of the order parameter. When the order parameter comprises several components arising from multiplicity in the same irreducible representation of symmetry, it can possess a nontrivial topology and acquire a Berry phase under the variation of thermodynamic parameters. To illustrate this idea, we investigate the superconducting phase transition of an electronic system with tetragonal symmetry and an attractive interaction involving two partial waves, both transforming in the trivial representation. By analyzing the time-dependent Ginzburg-Landau equation in the adiabatic limit, we show that the order parameter acquires a Berry phase after a cyclic evolution of parameters. We study two concrete models -- one preserving time-reversal symmetry and one breaking it -- and demonstrate that the nontrivial topology of the order parameter originates from thermodynamic analogs of gapless Dirac and Weyl points in the phase diagram. Finally, we identify an experimental signature of the topological Berry phase in a Josephson junction.

We show how arbitrary unit cells of periodic materials can be represented as graphs whose nodes represent atoms and whose weighted edges represent tunneling connections between atoms. Further, we present methods to calculate the band structure of a material with an arbitrary graphical representation, which allows one to study the Fermi level of the material as well as conductivity at zero temperature. We present results for both circular chains as well as randomly-generated unit cell structures, and also use this representation to show that the connectivity of the unit cell is not correlated to its band gap at half filling. This paper provides an introductory insight into the utilization of graph theory for computational solid-state physics.

We study the dynamic structure factor $S(k,\omega)$ of the spin-1/2 chain with long-range, power-law decaying unfrustrated (sign alternating) Heisenberg interactions $J_r \sim (-1)^{r-1} r^{-\alpha}$ by means of stochastic analytic continuation (SAC) of imaginary-time correlations computed by quantum Monte Carlo calculations. We do so in both the long-range antiferromagnetic (AFM, for $\alpha \lesssim 2.23$) and quasi ordered (QLRO, for $\alpha \gtrsim 2.23$) ground-state phases, employing different SAC parametrizations of $S(k,\omega)$ to resolve sharp edges characteristic of fractional quasi-particles and sharp peaks expected with conventional quasi-particles. In order to identify the most statistically accurate parametrization, we apply a newly developed cross-validation method as "model selection" tool. We confirm that the spectral function contains a power-law divergent edge in the QLRO phase and a very sharp (likely $\delta$-function) magnon peak in the AFM phase. From our SAC results, we extract the dispersion relation in the different regimes of the model, and in the AFM phase, we extract the weight of the magnon pole. In the limit where the model reduces to the conventional Heisenberg chain with nearest-neighbor interactions, our $S(k,\omega)$ agrees well with known Bethe ansatz results. In the AFM phase the low-energy dispersion relation is known to be nonlinear, $\omega_k \sim k^z$, and we extract the corresponding dynamic exponent $z(\alpha)$, which in general is somewhat above the form obtained in linear spin-wave theory. We also find a significant continuum above the magnon peak. This study serves as a benchmark for SAC/QMC studies of systems with a transition from conventional to fractionalized quasi-particles.

Predictions of topological p-wave superconductivity and Majorana zero modes (MZMs) in hybrid superconductor-semiconductor nanowires have been difficult to realize experimentally. Consequently, researchers are actively exploring alternative platforms for MZMs. In this work, we theoretically study depleted nanowires with intrinsic superconductivity (as opposed to proximity-induced). Using a self-consistent Hartree-Fock-Bogoliubov mean field theory, we compute the topological phase diagram versus Zeeman field and filling for intrinsic wires with attractive interactions. We find that, although intrinsic wires could be less vulnerable than hybrids to topology-adverse effects, such as disorder and metallization, they are hindered by a fundamental limitation of their own. Although a topological p-wave phase is indeed possible, it is far less robust than in hybrid Majorana nanowires. Instead of remaining stable beyond the topological transition, it is found to decay exponentially with Zeeman field, greatly reducing the parameter region with an appreciable topological gap.

Estimating the effective energy, $E_\text{eff}$ of a stationary probability distribution is a challenge for non-equilibrium steady states. Its solution could offer a novel framework for describing and analyzing non-equilibrium systems. In this work, we address this issue within the context of scalar active matter, focusing on the continuum field theory of Active Model B+. We show that the Wavelet Conditional Renormalization Group method allows us to estimate the effective energy of active model B+ from samples obtained by numerical simulations. We investigate the qualitative changes of $E_\text{eff}$ as the activity level increases. Our key finding is that in the regimes corresponding to low activity and to standard phase separation the interactions in $E_\text{eff}$ are short-ranged, whereas for strong activity the interactions become long-ranged and lead to micro-phase separation. By analyzing the violation of Fluctuation-Dissipation theorem and entropy production patterns, which are directly accessible within the WCRG framework, we connect the emergence of these long-range interactions to the non-equilibrium nature of the steady state. This connection highlights the interplay between activity, range of the interactions and the fundamental properties of non-equilibrium systems.

We propose a mechanism which can generate supercurrents in spin-orbit coupled superconductors with charged magnetic inclusions. The basic idea is that through spin-orbit interaction, the in-plane electric field near the edge of each inclusion appears to the electrons as an effective spin-dependent gauge field; if Cooper pairs can be partially spin polarized, then each pair experiences a nonzero \textit{net} transverse pseudo-gauge field. We explore the phenomenology of our mechanism within a Ginzburg-Landau theory, with parameters determined from a microscopic model. Depending on parameters, our mechanism can either enhance or reduce the total magnetization upon superconducting condensation. Given an appropriate distribution of inclusions, we show how our mechanism can generate superconducting vortices without any applied orbital magnetic field. Surprisingly, the vortices form \textit{nonlocally}; they are situated in between the inclusions. Our mechanism can produce similar qualitative behavior to the "magnetic memory effect" observed in 4Hb-TaS$_2$. However, the magnitude of the effect in that material seems larger than our model can naturally explain.

It is commonly believed that there are only two types of particle exchange statistics in quantum mechanics, fermions and bosons, with the exception of anyons in two dimension. In principle, a second exception known as parastatistics, which extends outside of two dimensions, has been considered but was believed to be physically equivalent to fermions and bosons. In this paper we show that nontrivial parastatistics inequivalent to either fermions or bosons can exist in physical systems. These new types of identical particles obey generalized exclusion principles, leading to exotic free-particle thermodynamics distinct from any system of free fermions and bosons. We formulate our theory by developing a second quantization of paraparticles, which naturally includes exactly solvable non-interacting theories, and incorporates physical constraints such as locality. We then construct a family of exactly solvable quantum spin models in one and two dimensions where free paraparticles emerge as quasiparticle excitations, and their exchange statistics can be physically observed and is notably distinct from fermions and bosons. This demonstrates the possibility of a new type of quasiparticle in condensed matter systems, and, more speculatively, the potential for previously unconsidered types of elementary particles.

Coupled many-body quantum systems give rise to rich emergent physics and abundance of both stationary and dynamical behaviours. Designing platforms with tunable and distinct forms of coupling gives new insight into the collective behaviour of the dimerised quantum systems. Fundamentally, two systems can exchange particles through either forbidden or allowed channels, underpinning evanescent and ballistic coupling mechanisms, respectively. Based on proximity, the former leads to large spectral splitting that defines, for instance, chemical binding energies, whereas the latter pushes for stringent phase-matching and synchronicity between oscillating degrees-of-freedom, analogous to phase-coupled harmonic oscillators, with a significantly smaller impact on the energy landscape. Here, we demonstrate an all-optically tunable evanescent-ballistic quantum fluid dimer based on hyperbolic exciton-polariton condensates in a photonic crystal waveguide. By changing the angle of the polariton dimer relative to the grating, the system transitions from an evanescently-coupled molecule with large mode-splitting to a ballistic condensate dimer with strict phase-matching conditions and rich interference patterns. We directly measure the condensate spectral features and mass flow subject to a saddle dispersion relation, and connect our results to mean field theory. These results showcase the potential of photonic crystals to study condensed matter phenomena lying at the interface between delay-coupled nonlinear oscillators and tight binding physics.

I consider the long-standing issue of the hermicity of the Dirac equation in curved spacetime metrics. Instead of imposing hermiticity by adding ad hoc terms, I renormalize the field by a scaling function, which is related to the determinant of the metric, and then regularize the renormalized field on a discrete lattice. I found that, for time-independent and diagonal metrics such as the Rindler, de~Sitter, and anti-de~Sitter metrics, the Dirac equation returns a hermitian or pseudohermitian ($\mathcal{PT}$-symmetric) Hamiltonian when properly regularized on the lattice. Notably, the $\mathcal{PT}$-symmetry is unbroken in the pseudohermitian cases, assuring a real energy spectrum with unitary time evolution. Conversely, considering a more general class of time-dependent metrics, which includes the Weyl metric, the Dirac equation returns a nonhermitian Hamiltonian with nonunitary time evolution. Arguably, this nonhermicity is physical, with the time dependence of the metric corresponding to local nonhermitian processes on the lattice and nonunitary growth or decay of the time evolution of the field. This suggests a duality between nonhermitian gain and loss phenomena and spacetime contractions and expansions. This metric-induced nonhermiticity unveils an unexpected connection between spacetime metric and nonhermitian phases of matter.

Topological zero modes in topological insulators or superconductors are exponentially localized at the phase transition between a topologically trivial and nontrivial phase. These modes are solutions of a Jackiw-Rebbi equation modified with an additional term which is quadratic in the momentum. Moreover, localized fermionic modes can also be induced by harmonic potentials in superfluids and superconductors or in atomic nuclei. Here, by using inverse methods, we consider in the same framework exponentially-localized zero modes, as well as gaussian modes induced by harmonic potentials (with superexponential decay) and polynomially decaying modes (with subexponential decay), and derive the explicit and analytical form of the modified Jackiw-Rebbi equation (and of the Schr\"odinger equation) which admits these modes as solutions. We find that the asymptotic behavior of the mass term is crucial in determining the decay properties of the modes. Furthermore, these considerations naturally extend to the nonhermitian regime. These findings allow us to classify and understand topological and nontopological boundary modes in topological insulators and superconductors.

We investigate ensembles of Matrix Product States (MPSs) generated by quantum circuit evolution followed by projection onto MPSs with a fixed bond dimension $\chi$. Specifically, we consider ensembles produced by: (i) random sequential unitary circuits, (ii) random brickwork unitary circuits, and (iii) circuits involving both unitaries and projective measurements. In all cases, we characterize the spectra of the MPS transfer matrix and show that, for the first two cases in the thermodynamic limit, they exhibit a finite universal value of the spectral gap in the limit of large $\chi$, albeit with different spectral densities. We show that a finite gap in this limit does not imply a finite correlation length, as the mutual information between two large subsystems increases with $\chi$ in a manner determined by the entire shape of the spectral density. The latter differs for different types of circuits, indicating that these ensembles of MPS retain relevant physical information about the underlying microscopic dynamics. In particular, in the presence of monitoring, we demonstrate the existence of a measurement-induced entanglement transition (MIPT) in MPS ensembles, with the averaged dimension of the transfer matrix's null space serving as the effective order parameter.

We explore the dissipative phase transition of the two-photon Dicke model, a topic that has garnered significant attention recently. Our analysis reveals that while single-photon loss does not stabilize the intrinsic instability in the model, the inclusion of two-photon loss restores stability, leading to the emergence of superradiant states which coexist with the normal vacuum states. Using a second-order cumulant expansion for the photons, we derive an analytical description of the system in the thermodynamic limit which agrees well with the exact calculation results. Additionally, we present the Wigner function for the system, shedding light on the breaking of the Z4-symmetry inherent in the model. These findings offer valuable insights into stabilization mechanisms in open quantum systems and pave the way for exploring complex nonlinear dynamics in two-photon Dicke models.

The Dicke-Ising model, one of the few paradigmatic models of matter-light interaction, exhibits a superradiant quantum phase transition above a critical coupling strength. However, in natural optical systems, its experimental validation is hindered by a "no-go theorem''. Here, we propose a digital-analog quantum simulator for this model based on an ensemble of interacting qubits coupled to a single-mode photonic resonator. We analyze the system's free energy landscape using field-theoretical methods and develop a digital-analog quantum algorithm that disentangles qubit and photon degrees of freedom through a parity-measurement protocol. This disentangling enables the emulation of a photonic Schr\"odinger cat state, which is a hallmark of the superradiant ground state in finite-size systems and can be unambiguously probed through the Wigner tomography of the resonator's field.

Nonlocal quantum games provide proof of principle that quantum resources can confer advantage at certain tasks. They also provide a compelling way to explore the computational utility of phases of matter on quantum hardware. In a recent manuscript [Hart et al., arXiv:2403.04829] we demonstrated that a toric code resource state conferred advantage at a certain nonlocal game, which remained robust to small deformations of the resource state. In this manuscript we demonstrate that this robust advantage is a generic property of resource states drawn from topological or fracton ordered phases of quantum matter. To this end, we illustrate how several other states from paradigmatic topological and fracton ordered phases can function as resources for suitably defined nonlocal games, notably the three-dimensional toric-code phase, the X-cube fracton phase, and the double-semion phase. The key in every case is to design a nonlocal game that harnesses the characteristic braiding processes of a quantum phase as a source of contextuality. We unify the strategies that take advantage of mutual statistics by relating the operators to be measured to order and disorder parameters of an underlying generalized symmetry-breaking phase transition. Finally, we massively generalize the family of games that admit perfect strategies when codewords of homological quantum error-correcting codes are used as resources.

Discrete-step walks describe the dynamics of particles in a lattice subject to hopping or splitting events at discrete times. Despite being of primordial interest to the physics of quantum walks, the topological properties arising from their discrete-step nature have been hardly explored. Here we report the observation of topological phases unique to discrete-step walks. We use light pulses in a double-fibre ring setup whose dynamics maps into a two-dimensional lattice subject to discrete splitting events. We show that the number of edge states is not simply described by the bulk invariants of the lattice (i.e., the Chern number and the Floquet winding number) as would be the case in static lattices and in lattices subject to smooth modulations. The number of edge states is also determined by a topological invariant associated to the discrete-step unitary operators acting at the edges of the lattice. This situation goes beyond the usual bulk-edge correspondence and allows manipulating the number of edge states without the need to go through a gap closing transition. Our work opens new perspectives for the engineering of topological modes for particles subject to quantum walks.

Energetic or "hot" electrons and holes generated from the decay of localized surface plasmons in metallic nanoparticles have great potential for applications in photocatalysis, photovoltaics, and sensing. Here, we study the generation of hot carriers in brick-shaped gold nanoparticles using a recently developed modelling approach that combines a solution to Maxwell's equation with large-scale tight-binding simulations to evaluate Fermi's Golden Rule. We find that hot-carrier generation depends sensitively on the aspect ratio of the nanobricks with flatter bricks producing a large number of energetic electrons irrespective of the light polarization. In contrast, the hot-carrier generation rates of elongated nanobricks exhibits a strong dependence on the light polarization. The insights resulting from our calculations can be harnessed to design nanobricks that produce hot carriers with properties tailored to specific device applications.

An adult human body is made up of some 30 to 40 trillion cells, all of which stem from a single fertilized egg cell. The process by which the right cells appear to arrive in their right numbers at the right time at the right place -- development -- is only understood in the roughest of outlines. This process does not happen in isolation: the egg, the embryo, the developing foetus, and the adult organism all interact intricately with their changing environments. Conceptual and, increasingly, mathematical approaches to modelling development have centred around Waddington's concept of an epigenetic landscape. This perspective enables us to talk about the molecular and cellular factors that contribute to cells reaching their terminally differentiated state: their fate. The landscape metaphor is however only a simplification of the complex process of development; it for instance does not consider environmental influences, a context which we argue needs to be explicitly taken into account and from the outset. When delving into the literature, it also quickly becomes clear that there is a lack of consistency and agreement on even fundamental concepts; for example, the precise meaning of what we refer to when talking about a `cell type' or `cell state.' Here we engage with previous theoretical and mathematical approaches to modelling cell fate -- focused on trees, networks, and landscape descriptions -- and argue that they require a level of simplification that can be problematic. We introduce random dynamical systems as one natural alternative. These provide a flexible conceptual and mathematical framework that is free of extraneous assumptions. We develop some of the basic concepts and discuss them in relation to now `classical' depictions of cell fate dynamics, in particular Waddington's landscape.

We explore pattern formation in an active fluid system involving two chemical species that regulate active stress: a fast-diffusing species ($A$) and a slow-diffusing species ($I$). The growth of species $A$ is modelled using a nonlinear logistic term. Through linear stability analysis, we derive phase diagrams illustrating the various dynamical regimes in parameter space. Our findings indicate that an increase in the P\'eclet number results in the destabilisation of the uniform steady state. In contrast, counter-intuitively, an increase in the nonlinear growth parameter of $A$ actually stabilises the homogeneous steady-state regime. Additionally, we observe that greater asymmetry between the species leads to three distinct dynamical phases, while low asymmetry fails to produce oscillatory instability. Numerical simulations conducted in instability regimes show patterns that range from irregular, arrhythmic configurations at high P\'eclet numbers to both transient and robust symmetry-breaking chimera states. Notably, these chimera patterns are more prevalent in the oscillatory instability regime, and our stability analysis indicates that this regime is the most extensive for high nonlinear growth parameters and moderately high P\'eclet numbers. Further, we also find soliton-like structures where aggregations of species $A$ merge, and new aggregations spontaneously emerge, and these patterns are prevalent in the phase of stationary instability. Overall, our study illustrates that a diverse array of patterns can emerge in active matter influenced by nonlinear growth in a chemical species, with chimeras being particularly dominant when the nonlinear growth parameter is elevated.

The physics of the SYK model at low temperatures is dominated by a soft mode governed by the Schwarzian action. In arXiv:1604.07818 the linearised action was derived from the soft mode contribution to the four-point function, and physical arguments were presented for its nonlinear completion to the Schwarzian. In this paper, we give two derivations of the full nonlinear effective action in the large $p$ limit, where $p$ is the number of fermions in the interaction terms of the Hamiltonian. The first derivation uses that the collective field action of the large-$p$ SYK model is Liouville theory with a non-conformal boundary condition that we study in conformal perturbation theory. This derivation can be viewed as an explicit version of the renormalisation group argument for the nonlinear soft mode action in arXiv:1711.08467. The second derivation uses an Ansatz for how the soft mode embeds into the microscopic configuration space of the collective fields. We generalise our results for the large-$p$ SYK chain and obtain a "Schwarzian chain" effective action for it. These derivations showcase that the large-$p$ SYK model is a rare system, in which there is sufficient control over the microscopic dynamics, so that an effective description can be derived for it without the need for extra assumptions or matching (in the effective field theory sense).

We present a scheme to realize a topological superconducting system supporting Majorana zero modes, within a number-conserving framework suitable for optical-lattice experiments. Our approach builds on the engineering of pair-hopping processes on a ladder geometry, using a sequence of pulses that activate single-particle hopping in a time-periodic manner. We demonstrate that this dynamic setting is well captured by an effective Hamiltonian that preserves the parity symmetry, a key requirement for the stabilization of Majorana zero modes. The phase diagram of our system is determined using a bosonization theory, which is then validated by a numerical study of the topological bulk gap and entanglement spectrum using matrix product states. Our results indicate that Majorana zero modes can be stabilized in a large parameter space, accessible in optical-lattice experiments.

Quantum dots (QDs) are pivotal for the development of quantum technologies, with applications ranging from single-photon sources for secure communication to quantum computing infrastructures. Understanding the electron dynamics within these QDs is essential for characterizing their properties and functionality. Here, we show how by virtue of the recently introduced quantum polyspectral analysis of transport measurements, the complex transport measurements of multi-electron QD systems can be analyzed. This method directly relates higher-order temporal correlations of a raw quantum point contact (QPC) current measurement to the Liouvillian of the measured quantum system. By applying this method to the two-level switching dynamics of a double QD system, we reveal a hidden third state, without relying on the identification of quantum jumps or prior assumptions about the number of involved quantum states. We show that the statistics of the QPC current measurement can identically be described by different three-state Markov models, each with significantly different transition rates. Furthermore, we compare our method to a traditional analysis via waiting-time distributions for which we prove that the statistics of a three-state Markov model is fully described without multi-time waiting-time distributions even in the case of two level switching dynamics. Both methods yield the same parameters with a similar accuracy. The quantum polyspectra method, however, stays applicable in scenarios with low signal-to-noise, where the traditional full counting statistics falters. Our approach challenges previous assumptions and models, offering a more nuanced understanding of QD dynamics and paving the way for the optimization of quantum devices.

Exchange-only (EO) spin qubits in quantum dots offer an expansive design landscape for architecting scalable device layouts. The study of two-EO-qubit operations, which involve six electrons in six quantum dots, has so far been limited to a small number of the possible configurations, and previous works lack analyses of design considerations and implications for quantum error correction. Using a simple and fast optimization method, we generate complete pulse sequences for CX, CZ, iSWAP, leakage-controlled CX, and leakage-controlled CZ two-qubit gates on 450 unique planar six-dot topologies and analyze differences in sequence length (up to 43% reduction) across topology classes. In addition, we show that relaxing constraints on post-operation spin locations can yield further reductions in sequence length; conversely, constraining these locations in a particular way generates a CXSWAP operation with minimal additional cost over a standard CX. We integrate this pulse library into the Intel quantum stack and experimentally verify pulse sequences on a Tunnel Falls chip for different operations in a linear-connectivity device to confirm that they work as expected. Finally, we explore architectural implications of these results for quantum error correction. Our work guides hardware and software design choices for future implementations of scalable quantum dot architectures.

Building on our recent study [https://doi.org/10.1021/acs.jpclett.3c02052, J. Phys. Chem. Lett. 14, 8780 (2023)], we explore the generalization of the ground-state Kohn-Sham (KS) formalism of density-functional theory (DFT) to the (singlet) excited states of the asymmetric Hubbard dimer at half-filling. While we found that the KS-DFT framework can be straightforwardly generalized to the highest-lying doubly-excited state, the treatment of the first excited state presents significant challenges. Specifically, using a density-fixed adiabatic connection, we show that the density of the first excited state lacks non-interacting $v$-representability. However, by employing an analytic continuation of the adiabatic path, we demonstrate that the density of the first excited state can be generated by a complex-valued external potential in the non-interacting case. More practically, by performing state-specific KS calculations with exact and approximate correlation functionals -- each state possessing a distinct correlation functional -- we observe that spurious stationary solutions of the KS equations may arise due to the approximate nature of the functional.

We propose and implement a comprehensive quantum compilation toolkit for solving the maximum independent set (MIS) problem on quantum hardware based on Rydberg atom arrays. Our end-to-end pipeline involves three core components to efficiently map generic MIS instances onto Rydberg arrays with unit-disk connectivity, with modules for graph reduction, hardware compatibility checks, and graph embedding. The first module (reducer) provides hardware-agnostic and deterministic reduction logic that iteratively reduces the problem size via lazy clique removals. We find that real-world networks can typically be reduced by orders of magnitude on sub-second time scales, thus significantly cutting down the eventual load for quantum devices. Moreover, we show that reduction techniques may be an important tool in the ongoing search for potential quantum speedups, given their ability to identify hard problem instances. In particular, for Rydberg-native MIS instances, we observe signatures of an easy-hard-easy transition and quantify a critical degree indicating the onset of a hard problem regime. The second module (compatibility checker) implements a hardware compatibility checker that quickly determines whether or not a given input graph may be compatible with the restrictions imposed by Rydberg quantum hardware. The third module (embedder) describes hardware-efficient graph embedding routines to generate (approximate) encodings with controllable overhead and optimized ancilla placements. We exemplify our pipeline with experiments run on the QuEra Aquila device available on Amazon Braket. In aggregate, our work provides a set of tools that extends the class of problems that can be tackled with near-term Rydberg atom arrays.

In quantum cryptography, fundamental laws of quantum physics are exploited to enhance the security of cryptographic tasks. Quantum key distribution is by far the most studied protocol to date, enabling the establishment of a secret key between trusted parties. However, there exist many practical use-cases in communication networks, which also involve parties in distrustful settings. The most fundamental quantum cryptographic building block in such a distrustful setting is quantum coin flipping, which provides an advantage compared to its classical equivalent. So far, few experimental studies on quantum coin flipping have been reported, all of which used probabilistic quantum light sources facing fundamental limitations. Here, we experimentally implement a quantum strong coin flipping protocol using single-photon states and demonstrate an advantage compared to both classical realizations and implementations using faint laser pulses. We achieve this by employing a state-of-the-art deterministic single-photon source based on the Purcell-enhanced emission of a semiconductor quantum dot in combination with fast polarization-state encoding enabling a quantum bit error ratio below 3%, required for the successful execution of the protocol. The reduced multi-photon emission yields a smaller bias of the coin flipping protocol compared to an attenuated laser implementation, both in simulations and in the experiment. By demonstrating a single-photon quantum advantage in a cryptographic primitive beyond QKD, our work represents a major advance towards the implementation of complex cryptographic tasks in a future quantum internet.

Balancing high sensitivity with a broad dynamic range (DR) is a fundamental challenge in measurement science, as improving one often compromises the other. While traditional quantum metrology has prioritized enhancing local sensitivity, a large DR is crucial for applications such as atomic clocks, where extended phase interrogation times contribute to wider phase range. In this Letter, we introduce a novel quantum deamplification mechanism that extends DR at a minimal cost of sensitivity. Our approach uses two sequential spin-squeezing operations to generate and detect an entangled probe state, respectively. We demonstrate that the optimal quantum interferometer limit can be approached through two-axis counter-twisting dynamics. Further expansion of DR is possible by using sequential quantum deamplification interspersed with phase encoding processes. Additionally, we show that robustness against detection noise can be enhanced by a hybrid sensing scheme that combines quantum deamplification with quantum amplification. Our protocol is within the reach of state-of-the-art atomic-molecular-optical platforms, offering a scalable, noise-resilient pathway for entanglement-enhanced metrology.

The quantum extremal island rule allows us to compute the Page curves of Hawking radiation in semi-classical gravity. In this work, we study the connection between these calculations and the thermalisation of chaotic quantum many-body systems, using a coarse-grained description of entanglement dynamics known as the entanglement membrane. Starting from a double-holographic model of eternal two-sided asymptotically AdS$_d$ ($d>2$) black hole each coupled to a flat $d$-dimensional bath, we show that the entanglement dynamics in the late-time, large-subregion limit is described by entanglement membrane, thereby establishing a quantitative equivalence between a semi-classical gravity and a chaotic quantum many-body system calculation of the Page curve.

The rotational states of ultracold polar molecules possess long radiative lifetimes, microwave-domain coupling, and tunable dipolar interactions. Coherent dynamics between pairs of rotational states have been used to demonstrate simple models of quantum magnetism and to manipulate quantum information stored as qubits. The availability of numerous rotational states has led to many proposals to implement more complicated models of quantum magnetism, higher-dimensional qudits, and intricate state networks as synthetic dimensions; however, these are yet to be experimentally realised. The primary issue limiting their implementation is the detrimental effect of the optical trapping environment on coherence, which is not easily mitigated for systems beyond two levels. To address this challenge, we investigate the applicability of magic-wavelength optical tweezer traps to facilitate multitransition coherence between rotational states. We demonstrate simultaneous second-scale coherence between three rotational states. Utilising this extended coherence, we perform multiparameter estimation using a generalised Ramsey sequence and demonstrate coherent spin-1 dynamics encoded in the rotational states. Our work paves the way to implementing proposed quantum simulation, computation, and metrology schemes that exploit the rich rotational structure of ultracold polar molecules.

Superfluid helium, the inviscid low-temperature phase of liquid \4He, enables investigation of flows with reduced dimensionality since, due to the vanishing viscosity, sub-micron flow channels can be constructed. In such strongly confined volumes filled with superfluid, the longitudinal acoustic wave is a coupled fluctuation of pressure and entropy density called fourth sound. In this work, we use multiple 4th sound acoustic modes inside a nano-superfluidic acoustic resonator in a pump-probe arrangement to observe localized clusters of quantized vortices leading to two-dimensional turbulence. The localised turbulence enables controllable and asymmetric dissipative coupling between acoustic modes. Furthermore, we derive a general procedure for analytically estimating the superfluid acoustic resonance frequencies inside a volume with mechanically compliant walls. Our work confirms earlier assumptions that turbulence in similar nanofluidic systems initially develops in localized areas of high shear. The multimode pump-probe methods presented here will allow future experiments to study the dynamics of two-dimensional quantum turbulence, e.g., the free decay.

Purpose: To theoretically and experimentally study implant lead tip heating caused by radiofrequency (RF) power deposition in different wire configurations that contain loop(s). Methods: Maximum temperature rise caused by RF heating was measured at 1.5T on 20 insulated, capped wires with various loop and straight segment configurations. The experimental results were compared with predictions from the previously reported simple exponential and the adapted transmission line models, as well as with a long-wavelength approximation. Results: Both models effectively predicted the trends in lead tip temperature rise for all the wire configurations, with the adapted transmission line model showing superior accuracy. For superior/inferior (S/I)-oriented wires, increasing the number of loops decreased the overall heating. However, when wires were oriented right/left (R/L) where the x-component of the electric field is negligible, additional loops increased the overall heating. Conclusion: The simple exponential and the adapted transmission line models previously developed for, and tested on, straight wires require no additional terms or further modification to account for RF heating in a variety of loop configurations. These results extend the usefulness of the models to manage implanted device lead tip heating and provide theoretical insight regarding the role of loops and electrical lengths in managing RF safety of implanted devices.

Deformed droplets are ubiquitous in various industrial applications, such as inkjet printing, lab-on-a-chip devices, and spray cooling, and can fundamentally affect the involved applications both favorably and unfavorably. Here, we employ many-body dissipative particle dynamics to investigate the oscillations of water droplets on a harmonically and horizontally vibrating, solid substrate. Three distinct scenarios of oscillations as a response to the substrate vibrations have been identified. The first scenario reflects a common situation where the droplet can follow the substrate vibrations. In the other two scenarios, favored in the case of hydrophilic substrates, droplet oscillations generate high shear rates that ultimately lead to droplet breakup. Leveraging our simulation model, the properties of the droplet and the mechanisms related to the oscillations are analyzed with a molecular-level resolution, while results are also put in the perspective of experiment. Our study suggests that the three scenarios can be distinguished by the contact-surface velocity of the oscillating droplet, with threshold velocities influenced by the substrate's wettability. Moreover, the mean magnitude of the particle velocity at the contact surface plays a key role in determining the three oscillation phases, suggesting that the capillary number of the oscillating droplet governs the phase behavior. Thus, our approach aims to optimize droplet oscillations and deformations on solid substrates, which have direct implications for technological applications.

With the development of any quantum technology comes a need for precise control of quantum systems. Here, we evaluate the impact of control noise on a quantum Otto cycle. Whilst it is postulated that noiseless quantum engines can approach maximal Otto efficiency in finite times, the existence of white noise on the controls is shown to negatively affect average engine performance. Two methods of quantum enhancement, counterdiabatic driving and quantum lubrication, are implemented and found to improve the performance of the noisy cycle only in specified parameter regimes. To gain insight into performance fluctuations, projective energy measurements are used to construct a noise-averaged probability distribution without assuming full thermalisation or adiabaticity. From this, the variances in thermodynamic currents are observed to increase as average power and efficiency improve, and are also shown to be consistent with known bounds from thermodynamic uncertainty relations. Lastly, by comparing the average functioning of the unmonitored engine to a projectively-measured engine cycle, the role of coherence in work extraction for this quantum engine model is investigated.