Quantum Gases
Anomalous Topological Bloch Oscillations under Non-Abelian Gauge Fields
Chunyan Li, Ce Shang and Boris A. Malomed
Topological Bloch oscillations are a hallmark of
quantum transport phenomenon in which wavepackets undergo oscillatory motion driven by the interplay between an external force and topological edge states and serve as a powerful dynamical probe for the
geometric properties of topological bands.
Spin-orbit coupling (SOC) has also emerged as a crucial ingredient for manipulating
quantum states in materials, with the corresponding gauge fields arising from the Rashba and Dresselhaus interactions. In this work, we investigate the propagation of spinor wavepackets in a honeycomb Zeeman
lattice governed by the Gross-Pitaevskii equation. By tuning the relative strengths of Rashba and Dresselhaus SOC, we engineer a non-Abelian gauge field that drives anomalous topological Bloch oscillations (ATBOs). Unlike conventional topological Bloch oscillation (TBOs), these ATBOs exhibit asymmetric motion, including a freezing effect in one half of the oscillation cycle, which can be tuned by the SOC parameters and external forces. Our findings establish SOC-based non-Abelian gauge fields as a powerful mechanism controlling topological
quantum dynamics, with implications for spintronic devices and
quantum data processing.
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Superconductivity
Microwave Vortex Motion Characterization of Nb$_3$Sn Coatings for Applications in High Magnetic Fields
Pablo Vidal García, Andrea Alimenti, Dorothea Fonnesu et al. (+8 more)
In this work, microwave measurements carried out in dielectric-loaded resonators exposed to high
magnetic fields are exploited to yield the surface impedance of Nb$_3$Sn superconducting coatings deposited via two different techniques: vapor tin
diffusion, and DC magnetron sputtering. The obtained data lead to qualitative interpretations on both the Nb$_3$Sn superconducting properties, and
vortex-dynamics and pinning, of each coating separately, as well as simple distinctive features when comparing those. When examining the respective surface impedances at varying field, it is expected that the studied films perform at substantially diverse magnitudes of flux-flow resistivity, but also in well-differentiated pinning regimes, yet the obtained surface resistances of both samples are comparable, thus demonstrating that there is room for film optimization at the expense of certain compromise between the parameters involved.
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All authors Pablo Vidal García, Andrea Alimenti, Dorothea Fonnesu, Davide Ford, Alessandro Magalotti, Giovanni Marconato, Cristian Pira, Sam Posen, Enrico Silva, Kostiantyn Torokhtii, Nicola Pompeo
Strongly Correlated Electrons
Computation of thermal entropy for the doped Hubbard Model
Yu-Feng Song, Youjin Deng and Yuan-Yao He
We develop a highly efficient framework for computing the thermal
entropy in the doped
Fermi-Hubbard model within the grand-canonical ensemble. The framework comprises four calculation schemes that express the
entropy as path integrals in the parameter space of temperature, interaction strength, and chemical potential. The integrands involve only fundamental observables, including the total energy,
fermion density, and double occupancy, which are readily accessible in a wide range of theoretical and numerical methods. We further derive useful Maxwell relations connecting the
entropy to other quantities and present practical formulas for directly evaluating the grand potential. As an application, we compute the
entropy of the doped Hubbard model in two and three dimensions, using the numerically unbiased auxiliary-field
quantum Monte Carlo method. The test results show excellent agreement across the different schemes and quantitatively verify the Maxwell relations, confirming the reliability of the framework. In two dimensions, we further
benchmark our
entropy results in physically relevant parameter regimes against diagrammatic Monte Carlo calculations and observe excellent quantitative consistency between the two approaches. By providing an efficient and broadly applicable route for
entropy evaluation, our work facilitates the thermodynamic characterization of complex correlated states in the doped Hubbard model.
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Statistical Mechanics
Resonances, Recurrence Times and Steady States in Monitored Noisy Qubit Systems
Shuanger Ma, Sabine Tornow and Eli Barkai
We study non-
equilibrium steady states and recurrence times in noisy, stroboscopically monitored
qubit systems using complete measurements. In the noiseless limit, recurrence times are integer-quantized, with dips to lower integers when sampling approaches revival conditions associated with ergodicity breaking. Using an IBM
quantum platform, we find that quantization is robust when sampling far from revivals, but breaks down dramatically near revivals: even weak noise produces large deviations and can invert the expected dips into pronounced peaks. To explain this behavior, we formulate a statistical-physics model of monitored noisy
circuits in which monitoring drives an effective infinite-temperature steady state while thermal-like relaxation competes to favor a low-temperature limit. We show that the sampling time tunes a crossover between these regimes, near revivals stabilizing low-temperature behavior, and far from revivals restoring infinite-temperature behavior – with noise strength and detuning acting as coupled small parameters near resonance.
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Strongly Correlated Electrons
Magnetic properties of a buckled honeycomb lattice antiferromagnet
A. Yadav, U. Jena, A. Pradhan et al. (+2 more)
The intriguing interplay between competing degrees of freedom in frustrated magnets can lead to non-trivial
magnetic phenomena with exotic low-energy excitations that are highly relevant for addressing some of the fundamental questions in
quantum condensed matter as well as potential technological applications. Herein, we report the synthesis and thermodynamic results on a frustrated magnet Co3ZnNb2O9. The Co2+ moments constitute buckled AB-type honeycomb layers in the ab-plane. The temperature-dependent
magnetic susceptibility shows a sharp anomaly at 14 K, indicating the onset of long-range
magnetic ordering. The Curie-Weiss fit of the
magnetic susceptibility above 100 K, yields a Curie-Weiss temperature of -70 K, suggesting strong
antiferromagnetic (AFM) interactions between the Co2+
spins and an effective
magnetic moment of 5.54 muB, indicating the presence of unquenched orbital angular momentum. A field-induced
spin-flop-like metamagnetic transition below the ordering temperature is characterized by a critical
magnetic field of 1.2 T. The specific heat shows a lambda-type anomaly at 14 K, confirming the presence of long-range
magnetic ordering, due to finite interlayer interaction. Interestingly, our study of the magnetocaloric effect near the transition temperature revealed an
entropy change of 2.81 J/kg.K, which is ascribed to competing interactions, underlying anisotropy, and reduced net magnetization lead to relatively small isothermal
entropy changes that suggest that frustrated honeycomb magnets are promising contenders for field-induced exotic phases and magnetocaloric response.
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All authors A. Yadav, U. Jena, A. Pradhan, Satish K., P. Khuntia
Strongly Correlated Electrons
Photoemission Signatures of Photoinduced Carriers and Excitons in One-Dimensional Mott Insulators
Taiga Nakamoto, Yuta Murakami and Naoto Tsuji
We theoretically study photoemission spectra for photodoped one-dimensional Mott
insulators that can host
excitons, and show that their spectral characteristics differ qualitatively from those of photodoped
semiconductors. In conventional
semiconductors, photoemission spectra are well understood; free charge carriers generate spectral weight near the bottom of the conduction band, while the formation of
excitons leads to replica features of the valence band appearing inside the band gap. In one-dimensional Mott
insulators, on the other hand, strong correlations give rise to fractionalized elementary excitations-spinons, holons, and doublons-which fundamentally modify the photoemission response. We find that when photodoped carriers, i.e., doublons and holons, remain unbound, the photoemission spectrum directly reflects the dispersion of spinons, i.e.,
magnetic elementary excitations. In contrast, when a doublon and a holon form an excitonic bound state, replica structures of the lower Hubbard band emerge inside the Mott gap, carrying contributions from both spinon and holon excitations. Importantly, the distribution of the in-gap signal depends sensitively on the degree of doublon-holon binding. The origin of these spectral features is clarified through a combination of exact diagonalization and the slave-particle approach. These results indicate that photoemission from photoinduced carriers and
excitons in strongly correlated electron systems can provide information on
magnetic properties and carrier-binding properties.
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Materials Science
Deterministic nucleation of nanocrystal superlattices on 2D perovskites for light-funneling heterostructures
Umberto Filippi, Alexander Schleusener, Simone Lauciello et al. (+4 more)
Semiconductor heterostructures that combine components with different dimensionality provide an interesting way to manipulate the physical properties of the resulting material. Two-dimensional lead halide perovskites crystallize as flat microcrystals and have efficient in-plane
exciton mobility, while perovskite nanocrystals are efficient emitters with a tunable bandgap that can self-assemble into microscopic superlattices. However, combining such intricate architectures into
heterostructures has been challenging due to the mismatch in solubility properties and the challenging transfer procedures. Here we realize
heterostructures where CsPbBr3 nanocrystal superlattices are deterministically grown along the faces of PEA2PbBr4 two-dimensional layered perovskite microcrystals. The growth can be limited to the lateral faces of the microcrystals and result in core-crown epitaxial
heterostructures, or extended to the vertical direction leading to core-shell-like structures. The growth method is simple yet effective and versatile, and promises to be expanded to a large variety of other materials. We demonstrate that these
heterostructures can be employed as efficient light-harvesting systems. In fact, energy can be transferred from the two-dimensional microcrystal domain to the superlattices, enabling switching between linear and non-linear carrier recombination regimes by tuning the excitation fluence. Moreover, by exploiting the lifetime shortening of CsPbBr3 nanocrystal emission upon sample cooling, we ensure that energy transfer occurs after the biexcitonic and single-excitonic decays of the nanocrystals, effectively extending the radiative recombination of superlattices.
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All authors Umberto Filippi, Alexander Schleusener, Simone Lauciello, Roman Krahne, Dmitry Baranov, Liberato Manna, Masaru Kuno
Statistical Mechanics · Cross-listed from quant-ph
Lindbladian spectral statistics beyond no-jump Hamiltonians: roles of recycling and Liouville-space structure
Dingzu Wang, Hao Zhu, Guo-Feng Zhang et al. (+1 more)
Spectral statistics probe integrability versus chaos and have recently been extended to Markovian open
quantum systems described by Lindbladians, whose
quantum-trajectory unraveling decomposes the
evolution into no-jump dynamics generated by an effective non-Hermitian
Hamiltonian and recycling jumps. In this work, we perform spectrum-statistics diagnostics for Lindbladians and their effective non-Hermitian
Hamiltonians. We show that recycling processes,
symmetry constraints, and the Liouville-space structure crucially shape the spectral correlations. In particular, we identify a family of spectrally separable Lindbladians whose spectra exhibit robust Poisson statistics, despite the effective non-Hermitian
Hamiltonian varying from Poisson to strongly correlated complex-spectrum statistics. Our work establishes a unified spectral-statistics characterization for Lindbladians and their associated effective non-Hermitian
Hamiltonians, deepening our understanding of spectral properties in open many-body systems.
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All authors Dingzu Wang, Hao Zhu, Guo-Feng Zhang, Dario Poletti
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Cavity Control of Strongly Correlated Electrons Beyond Resonant Coupling
Lukas Grunwald, Xinle Cheng, Emil Viñas Boström et al. (+4 more)
Interfacing materials with electromagnetic cavities offers a route to modify
equilibrium properties through structured
vacuum fluctuations. The coupling between light and correlated electrons lacks a characteristic energy scale, making
vacuum induced ground state modifications of such systems inherently off-resonant and sensitive to the full
photon mode structure. We develop a consistent cavity-QED formalism for dispersive electromagnetic environments in the Coulomb gauge, capturing both dynamical dressing via the vector potential and static screening by the dielectric. With this formalism, we perform a non-perturbative study of the cavity-induced modification of magnetism in the Hubbard model close to half-filling, including all cavity modes and with parameters determined from first principles. At half-filling, we show that the modification of the
magnetic exchange interaction $J$ is controlled by a generalized Purcell factor, proportional to the frequency integrated photonic density of states relative to free space. This result identifies polaritonic surface cavities as promising platforms to modify correlated systems. For the surface cavity a competition between static screening and dynamical dressing via the vector potential leads to a net enhancement of $J$, directly observable in two-
magnon Raman spectroscopy. The inclusion of screening is essential to obtain even qualitatively correct results. At weak doping, a variational exact diagonalization of the cavity-coupled $t$-$J$ polaron reveals that a low-frequency surface cavity can reverse the nodal-antinodal dichotomy of the bare polaron dispersion. This effect lies beyond mean field theory and is observable via ARPES measurements. Our framework establishes a concrete design principle linking cavity geometry to material response in the off-resonant regime, which will guide future experimental and theoretical explorations.
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All authors Lukas Grunwald, Xinle Cheng, Emil Viñas Boström, Michael Ruggenthaler, Marios H. Michael, Dante M. Kennes, Angel Rubio
Mesoscale and Nanoscale Physics
Peltier cooling in Corbino-geometry quantum Hall systems
Akira Endo and Yoshiaki Hashimoto
Quantum Hall systems having Corbino geometry are expected to have a large Peltier coefficient $\Pi_{rr}$ in the
quantum Hall plateau region. We present an analytic formula for $\Pi_{rr}$ calculated employing the spectral conductivity obtained based on the self-consistent Born approximation. The coefficient $\Pi_{rr}$ is shown to have a large negative (positive) value just above (below) an integer Landau-level filling, with the absolute value $|\Pi_{rr}|$ increasing with decreasing temperature or decreasing disorder, and approaching the saw-tooth shape $- (E_{N_\mathrm{F} \sigma_\mathrm{F}}-\zeta)/e$ in the limit of vanishing disorder, where $E_{N_\mathrm{F} \sigma_\mathrm{F}}$ is the highest occupied Landau level and $\zeta$ is the chemical potential. As an initial attempt to experimentally observe the effect of the large $|\Pi_{rr}|$, we measure the electron temperature $T_\mathrm{out}$ near the outer perimeter of a Corbino disk, applying a radial dc current $I_\mathrm{dc}$. The temperature $T_\mathrm{out}$ is observed to increase or decrease depending on the direction of $I_\mathrm{dc}$ and the sign of $\Pi_{rr}$ as expected from the Peltier effect. Notably, $T_\mathrm{out}$ becomes lower than the bath temperature for outward (inward) $I_\mathrm{dc}$ in the region where $\Pi_{rr} < 0$ ($\Pi_{rr} > 0$).
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Soft Condensed Matter
Navigating complex phase diagrams in soft matter systems
Michael Wassermair, Gerhard Kahl, Roland Roth et al. (+1 more)
Colloidal fluids can exhibit complex phase behavior and determining phase diagrams via experiments or computer simulations can be laborious. We demonstrate that the dispersion relation $\omega(k)$, obtained from dynamical density functional theory for the uniform density system, is a highly versatile tool for predicting where in the phase diagram complex
crystals form. The sign of $\omega(k)$ determines whether density modes with wavenumber $k$ grow or decay over time. We demonstrate the predictive power by investigating the complex phase behavior of particles interacting via core-shoulder pair potentials. With complementary Monte Carlo simulations, we show that regions of the phase diagram where $\omega(k)$ has one or several unstable (growing) wavenumbers are also where crystalline phases occur. Going further, by tuning these unstable wavenumbers via the interaction-potential and state-point parameters, we design systems with quasicrystals in the phase diagram. We identify a system with a certain shoulder-range exhibiting at least 10 different phases. Our general approach accelerates considerably the mapping of complex phase diagrams, crucial for the design of new materials.
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All authors Michael Wassermair, Gerhard Kahl, Roland Roth, Andrew J. Archer
Soft Condensed Matter
Avalanches in the Random Organization Model with long-range interactions
T. Jocteur, K. Martens, R. Mari et al. (+1 more)
Oscillatory sheared suspensions, when observed stroboscopically, exhibit a reversible-irreversible transition as a function of the strain amplitude, which is a kind of absorbing phase transition. So far studies of this transition focused on global quantities, e.g. quantifying the irreversibility on one side of the transition or the time to reach a reversible state on the other side. Here, motivated by the kin depinning transition, we focus on the intermittent dynamics near the transition. We perform simulations of a modified Random Organization Model (ROM), a minimal particle model which we recently adapted to take into account the generic presence of long-range interactions mediated by the fluid, taking the power-law-decay exponent $\alpha$ as an additional control parameter of the model. We show that at the absorbing phase transition, this model displays power-law-distributed avalanches. We characterize the avalanche statistics in terms of avalanche size, duration and number of particles involved, and we determine the associated exponents. By varying the exponent $\alpha$, the fractal dimension of avalanches crosses space dimension $d$, inducing a qualitative change of the spatial structure of avalanches, from compact avalanches when interactions have a short range, to sparse avalanches when interactions are long-ranged. Finally, we characterize the clusters within the avalanches, which we also find power-law distributed.
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All authors T. Jocteur, K. Martens, R. Mari, E. Bertin
Materials Science
Andriani Vervelaki, Boris Gross, Daniel Jetter et al. (+11 more)
The
quantum anomalous
Hall effect has been observed in several magnetically doped topological
insulators, where its robustness and macroscopic magnetization properties have been taken to suggest the presence of long-range
ferromagnetic order. However, experiments in such systems have found evidence for both long- and short-range order, leaving the precise nature of the magnetism in these systems unclear. Here, we use scanning superconducting
quantum interference device microscopy to study
magnetic domains in V-doped (Bi,Sb)$_2$Te$_3$ exhibiting a
quantum anomalous
Hall effect with precise quantization. By imaging stray
magnetic fields as a function of applied field, we map the formation and
evolution of domains through
magnetic reversal. We reconstruct the magnetization configuration underlying the measured stray field and find that
magnetic domains and crystallographic grains are of similar size. Moreover,
magnetic reversal is found to occur through domain expansion, typical of ferromagnets, rather than through nucleation at random sites. Our measurements thus reveal a coexistence of both local
magnetic interactions within crystallographic grains and long-range
ferromagnetic coupling between grains. This behavior in V-doped (Bi,Sb)$_2$Te$_3$ is markedly distinct from that previously reported for Cr-doped (Bi,Sb)$_2$Te$_3$.
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All authors Andriani Vervelaki, Boris Gross, Daniel Jetter, Katharina Kress, Timur Weber, Dieter Koelle, Kajetan M. Fijalkowski, Martin Klement, Nan Liu, Karl Brunner, Charles Gould, Laurens W. Molenkamp, Martino Poggio, Floris Braakman
Materials Science
Microscopic Origin of Temperature-Dependent Anisotropic Heat Transport in Ultrawide-Bandgap Rutile GeO2
Pouria Emtenani, Marta Loletti, Felix Nippert et al. (+7 more)
Ultrawide-bandgap rutile GeO2 is emerging as a promising
semiconductor for power electronics, where efficient heat dissipation is essential to suppress self-heating and ensure device reliability. However, the temperature dependence and microscopic origin of its anisotropic heat transport have remained experimentally unresolved. Here, temperature-dependent time-domain thermoreflectance measurements combined with first-principles
phonon transport calculations are used to quantify the thermal conductivity of single-
crystal rutile GeO2 from 80 to 350 K along [001] and [110]. At 295 K, the thermal conductivity reaches 47.5 W m^-1 K^-1 along [001] and 32.5 W m^-1 K^-1 along [110], corresponding to an anisotropy ratio of 1.46, in good agreement with theory. Rather than following a simple T^(-1) law, the thermal conductivity exhibits an approximate T^(-1.4) dependence, indicating additional scattering beyond purely three-
phonon-limited transport. Mode-resolved analysis reveals that the room-temperature anisotropy originates from the combined effect of larger
phonon group velocities along [001] and direction-dependent
phonon lifetimes. Upon cooling, depopulation of high-frequency
phonons progressively suppresses their contribution to heat transport and reduces the anisotropy. The temperature-dependent thermal boundary conductance of Al/rutile GeO2 interfaces is further resolved, and the scaled conductance indicates predominantly elastic interfacial transport. These findings establish the microscopic basis of bulk and interfacial heat transport in rutile GeO2 and position this material as a promising thermally robust platform for ultrawide-bandgap electronics.
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All authors Pouria Emtenani, Marta Loletti, Felix Nippert, Eduardo Bede Barros, Zbigniew Galazka, Hans Tornatzky, Christian Thomsen, Juan Sebastian Reparaz, Riccardo Rurali, Markus R. Wagner
Quantum Gases
Vortex Retention Mediated Turbulent Transitions in Self-Gravitating Bosonic and Axionic Condensates
Anirudh Sivakumar, Sanjay Shukla, Rahul Pandit et al. (+2 more)
We investigate turbulent
spin-down dynamics in self-gravitating Bose-Einstein condensates, comparing purely bosonic and axionic (higher-order interacting) systems. Through simulations of the Gross-Pitaevskii-Poisson system, we study condensates pinned to a crust potential undergoing rapid rotation slowdown. We find that axionic condensates exhibit more uniform density profiles and smaller sizes compared to their bosonic counterparts for similar interaction strengths, which facilitates earlier
vortex entry. The sudden
spin-down triggers
vortex depinning and a turbulent cascade. For comparable sizes, both systems exhibit a short-lived Kolmogorov energy cascade ($k^{-5/3}$ scaling) followed by a transition to Vinen
turbulence ($k^{-1}$ scaling). Crucially, their responses diverge with increasing interaction strength (and thus condensate size): the axionic system increasingly deviates from Kolmogorov scaling because of enhanced
vortex retention, a trend quantitatively confirmed by analyzing the
vortex fraction and its dependence on the final rotation frequency. Spectral analysis reveals that the growth of incompressible energy is primarily driven by
quantum pressure during
vortex detachment, rather than by compressible flows. The compressible spectrum shows thermalization ($k$ scaling). Our results demonstrate how distinct nonlinearities govern
vortex dynamics and turbulent dissipation in self-gravitating
quantum fluids.
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All authors Anirudh Sivakumar, Sanjay Shukla, Rahul Pandit, Pankaj Kumar Mishra, Paulsamy Muruganandam
Materials Science
Bridging Crystal Structure and Material Properties via Bond-Centric Descriptors
Jian-Feng Zhang, Ze-Feng Gao, Xiao-Qi Han et al. (+7 more)
Although chemical bonding is the fundamental mechanistic bridge connecting atomic structure to macroscopic material properties, current data-driven materials science largely treats it as an implicit "black box". Existing machine learning (ML) models rely predominantly on
geometric coordinates, forcing them to implicitly relearn complex
quantum mechanics from scratch. This lack of intermediate physical features limits model interpretability and generalizability, particularly when training data is scarce. To solve this problem, we introduce MattKeyBond, a bond-centric materials database that explicitly maps the local electronic landscape and bonding interactions of materials. Building on this, we propose Bonding Attractivity (BA), a novel element-specific descriptor that quantifies the intrinsic capability of atoms to form covalent networks. By providing pre-calculated, energy-dimensional bonding descriptors, MattKeyBond transforms the implicit "black box" into physically interpretable features. This strategy relieves ML models from the burden of deducing physical laws from pure geometry, enabling accurate predictions even with limited data and seamlessly integrating electronic structure theory into modern AI workflows.
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All authors Jian-Feng Zhang, Ze-Feng Gao, Xiao-Qi Han, Bo Zhan, Dingshun Lv, Miao Gao, Kai Liu, Xinguo Ren, Zhong-Yi Lu, Tao Xiang
Mesoscale and Nanoscale Physics
Boltzmann-Bloch Equation Approach to the Theory of the Optical Inter- and Intraband Response in Noble Metals
Robert Lemke, Matthias Rössle, Holger Lange et al. (+2 more)
In this paper we introduce momentum-resolved metal Boltzmann-Bloch equations (MBBE) for the combined description of electronic intra- and interband processes in noble metals. This microscopic framework incorporates a full treatment of many-body electron-electron and electron-
phonon interactions, relevant for relaxation and dephasing processes after optical excitation. For the example of gold, we calculate the linear optical response for near-infrared and visible energies. This provides insight into the interplay of microscopic processes hidden in phenomenological Drude-Lorentz models. The complex geometry of the
Fermi surface is treated by an anisotropic electronic dispersion model, which is necessary to explain the temperature dependent spectrum over the whole frequency range of intra- and interband transitions.
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All authors Robert Lemke, Matthias Rössle, Holger Lange, Andreas Knorr, Jonas Grumm
Mesoscale and Nanoscale Physics
Fine-grained topological structures hidden in the Fermi sea
Wei Jia
The geometry of the
Fermi sea hosts a unique form of
quantum topology, playing an equally significant role as the geometry of wave function. It governs the conductance quantization of a metal and is characterized by the Euler characteristic $\chi_F$, offering a new perspective in the study of topological
quantum matter. Here, we reveal a class of fine-grained
topology in the
Fermi sea, whose characterization goes beyond $\chi_F$. Such topological structure in the
symmetry-protected Morse-function regime leads to a nontrivial result that two
Fermi seas with identical $\chi_F$ but different fine-grained
topologies cannot be connected without a Lifshitz transition. To encode this structure, we introduce a structural resolution factor, which exactly captures the deeper topological information of the
Fermi sea. When further considering the attractive Hubbard interaction of electrons on
Fermi surfaces, we demonstrate that the resulting
chiral topological superconducting phases can inherit the fine-grained
Fermi sea
topology of their parent metallic bands, with differences in these fine-grained structures giving rise to anomalous Majorana boundary states at the interface between two metal/
superconductor heterojunctions. This work opens an avenue for exploring the topological richness of the
Fermi sea.
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Soft Condensed Matter
Guided elastic waves informed material modelling of soft incompressible media
Pierre Chantelot, Samuel Croquette and Fabrice Lemoult
Identifying a universal material constitutive law, that describes the mechanical response of rubber-like solids for all deformation fields and achievable extensions, is an outstanding challenge. Here, we propose to exploit the propagation of elastic waves and demonstrate that monitoring incremental guided wave propagation in an elastomer plate undergoing uniaxial extension reveals model sensitivities that are inaccessible in the corresponding static test. We measure the dispersion relations of the three zero-order guided modes, propagating parallel and perpendicular to the direction of imposed elongation. We compare them with predictions from the acoustoelastic theory, that also take into account material rheology, using parameters extracted from fitting the uniaxial stress-strain curve across three successive elongation regimes, following the methodical procedure of Destrade $\textit{et al.}$ (Proc. R. Soc. A 2017). We evidence that our approach lifts the degeneracy between hyperelastic models with different functional forms of the so-called $C_2$ term, which remain undistinguishable from static uniaxial tension stress-strain measurements alone. However, like their static counterpart, our dynamics measurements cannot distinguish between different generalized neo-Hookean models.
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Materials Science · Cross-listed from physics.optics
Phonon-modulated Kerr nonlinearity in ultrathin 2H-MoTe2
Shaoxiang Sheng, Yang Luo, Chenyu Wang et al. (+8 more)
Controlling nonequilibrium responses in optically driven
quantum materials is essential for advancing applications in energy conversion, ultrafast electronics, and
quantum computation. Nonlinear optical spectroscopy serves as a powerful tool to investigate ultrafast electron and
phonon dynamics in these systems; however, conventional nonlinear approaches often require intense
laser pulses (> 10 GW/cm2) and typically encounter a strong background. Here, we introduce a phase-sensitive nonlinear spectroscopic technique that operates at low
laser powers (~ 10 kW/cm2, pulse energies ~ 10 pJ) and enables real-time monitoring and active control of coherent
phonons in a few-layer (three to five) thick 2H-MoTe2. Upon excitation with ultrashort (~ 10 fs) pump pulses, we achieve displacive excitation of coherent
phonons, which periodically modulate the Kerr nonlinearity of the material, leading to cross-phase modulation (XPM) of a delayed probe pulse. This phase modulation induces spectral broadening and oscillations in the center of mass (COM) of the probe spectrum in time, enabling the detection of subtle nonlinear optical responses in a background-free manner. The nonlinear response can be selectively amplified or attenuated by adjusting the strength of the pump pulse, which controls the distribution of photoexcited carriers in the electronic bands. By combining two-color nondegenerate pump-probe measurements and time-dependent density-functional theory (TDDFT) calculations, we directly resolve the coupled nonequilibrium electronic and
phonon dynamics. A dual-pump pulse scheme enables precise control of
phonon oscillations, allowing selective activation or suppression of specific
phonon modes and correspondingly the modulation of the Kerr nonlinearity.
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All authors Shaoxiang Sheng, Yang Luo, Chenyu Wang, Sayooj Sateesh, Yaxian Wang, Marko Burghard, Sayantan Patra, Bhumika Chauhan, Ashish Arora, Sheng Meng, Manish Garg
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Certifying ergotropy under partial information
Egle Pagliaro, Leonardo Zambrano, Mir Alimuddin et al. (+3 more)
Ergotropy, the maximum work extractable from a
quantum system, is a central resource in
quantum physics. Computing ergotropy is well established when the system state is fully known, but its estimation under partial information remains an open problem. Here we introduce a general certification framework that lower bounds ergotropy using only the expectation values of a limited set of arbitrary observables. The method naturally applies in the finite-statistics regime, yielding confidence-certified bounds that explicitly incorporate shot noise. We
benchmark our approach on both synthetic data and experimental measurements from an IBM
quantum processor. This establishes a robust and experimentally accessible tool for certifying extractable work in realistic
quantum settings.
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All authors Egle Pagliaro, Leonardo Zambrano, Mir Alimuddin, Alioscia Hamma, Antonio Acín, Donato Farina
Strongly Correlated Electrons · Cross-listed from quant-ph
Quantum Advantage: a Tensor Network Perspective
Augustine Kshetrimayum, Saeed S. Jahromi, Sukhbinder Singh et al. (+1 more)
We review the recent
quantum advantage experiments by IBM, D-Wave, and Google, focusing on cases where efficient classical simulations of the experiment were demonstrated or attempted using tensor network methods. We assess the strengths and limitations of these tensor network-based approaches and examine how the interplay between classical simulation and
quantum hardware has advanced both fields. Our goal is to clarify what these results imply for the next generation of
quantum advantage experiments. We identify regimes and system features that remain challenging for current tensor network approaches, and we outline directions where improved classical methods could further raise the standard for claiming
quantum advantage. By analyzing this evolving competition, we aim to provide a clear view of where genuine, scalable
quantum advantage is most likely to emerge.
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All authors Augustine Kshetrimayum, Saeed S. Jahromi, Sukhbinder Singh, Román Orús
Soft Condensed Matter
Elastocapillary lifting and encapsulation of water by a triangular elastic film under gravity
Kyoko Shibata, Hana Kanda, Yoshimi Tanaka et al. (+1 more)
We investigate the encapsulation of water by a thin elastic film as a minimal model of elastocapillary self-folding with fluid transport. An equilateral triangular polydimethylsiloxane film is lifted quasi-statically from a water surface, while its side length and thickness are systematically varied. Depending on these parameters, the film exhibits three distinct morphologies: folding, recoiling, and
liquid encapsulation. We show that the observed morphology is selected by the competition between surface energy, gravitational energy of the
liquid, and bending energy of the film. In particular, encapsulation occurs in a narrow parameter region corresponding to the intersection of the elastocapillary, elastogravity, and capillary length scales. This result provides a simple physical criterion for
liquid encapsulation by elastic films, based on the balance of bending, capillary, and gravitational energies.
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All authors Kyoko Shibata, Hana Kanda, Yoshimi Tanaka, Yutaka Sumino
Mesoscale and Nanoscale Physics
Longitudinal Nonreciprocal Charge Transport with Time Reversal Symmetry
Harsh Varshney and Amit Agarwal
Longitudinal nonreciprocal charge transport is usually associated with broken time-reversal
symmetry, either from
magnetic order or an external
magnetic field. Here, we show that it can also arise in nonmagnetic conductors preserving time-reversal
symmetry through disorder-induced asymmetric scattering. Within a semiclassical Boltzmann theory, skew-scattering and side-jump processes generate a finite longitudinal current quadratic in the electric field. Our
symmetry analysis identifies 42 point groups that allow this longitudinal nonreciprocal response. As a concrete example, gated Bernal-stacked
bilayer graphene shows a gate-tunable nonreciprocal response with clear enhancement near its Lifshitz transition. These results identify disorder-driven asymmetric scattering as a route to bulk longitudinal nonreciprocal charge transport in crystalline conductors.
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Statistical Mechanics
Role of inertia on the performance of Brownian gyrators
Thalyta T. Martins, Ines Ben-Yedder, Alex Fontana et al. (+1 more)
Understanding the role of inertia in nanoscale heat transport is fundamental to the design of efficient nano-thermodynamics systems. In this work, we experimentally address the non-
equilibrium dynamics of a Brownian gyrator, a paradigmatic model for nano-heat machines, that converts heat flow between two thermal baths into steady-state rotation. Using an optically levitated nanoparticle in a controlled
vacuum environment, we study the transition from overdamped to underdamped dynamics of the gyrator. We demonstrate that, while the spatial signature of the non-
equilibrium steady state vanishes as damping decreases, the rotational dynamics and energetics are optimized at a critical damping. Our findings reveal the importance of inertia for maximising the performance of nanoscale machines and provide fundamental insights into the design of efficient nano heat engines and processes.
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All authors Thalyta T. Martins, Ines Ben-Yedder, Alex Fontana, Loïc Rondin
Statistical Mechanics
Extreme value statistics and some applications in statistical physics
Marcin Piotr Pruszczyk and Gregory Schehr
These notes are based on lectures delivered by G. Schehr at the XVIth School on Fundamental Problems in Statistical Physics (FPSP), held in Oropa (Italy) from 30 June to 11 July 2025. After a brief introduction to extreme value statistics (EVS) for independent and identically distributed (IID) random variables, we discuss several paradigmatic examples of strongly correlated systems where classical extreme value theory no longer applies. In particular, we focus on time series generated by random walks and Brownian motion, as well as on
eigenvalue statistics in random
matrix theory. Emphasis is placed on applications of EVS to fundamental problems in statistical physics and disordered systems, including the Random Energy Model,
stochastic search problems, as well as fluctuating interfaces, and directed
polymers in random media within the Kardar-Parisi-Zhang universality class.
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Materials Science
Phonon Band Center: A Robust Descriptor to Capture Anharmonicity
Madhubanti Mukherjee, Ashutosh Srivastava and Abhishek Kumar Singh
Understanding anharmonicity is crucial for designing materials with desired
lattice thermal conductivity. Designing a material descriptor that effectively captures anharmonicity while being cost-effective remains a significant challenge. This work proposes a simple metric that helps explain the diversity in
lattice thermal conductivity (kl) among materials by quantifying their anharmonic effects. This descriptor "
phonon band center" (PBC) encapsulates the critical factors associated with the physics of
phonon scattering, revealing a simple inverse relationship with the Gruneisen parameter, the response of
phonons with changing volume, and strong correlation with
lattice thermal conductivity. This metric has been established using the chalcopyrite class of materials and subsequently validated across various classes of materials using experimental kl. Our approach effectively differentiates materials based on PBC, thereby streamlining the identification of candidates with desirable kl.
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Materials Science
Direct observation of strain and confinement shaping the hole subbands of Ge quantum wells
Enrico Della Valle, Arianna Nigro, Miki Bonacci et al. (+6 more)
Germanium-silicon-germanium (Ge/Si$_{x}$Ge$_{1-x}$)
heterostructures have emerged as a promising platform for hole-
spin quantum technologies and high-mobility electronics, where strain and
quantum confinement strongly reshape the Ge valence bands. However, the momentum-resolved valence-band structure of buried strained Ge
quantum wells has so far been inferred only indirectly. Here we use soft X-ray angle-resolved photoemission spectroscopy (SX-ARPES) to directly probe the electronic structure of strained Ge
quantum wells embedded in SiGe barriers. We resolve strain-split and size-quantized valence subbands, determine their heavy-hole, light-hole and split-off composition, and measure the valence-band offset at the Ge/SiGe heterojunction. Comparison with ab initio calculations shows that an accurate description requires explicit inclusion of the confinement potential imposed by the SiGe barrier, which plays a decisive role in determining the dispersion, ordering and mixing of the hole states. Our results provide the first direct experimental picture of how strain and confinement determine the valence-band structure of Ge
quantum wells, establishing a foundation for predictive modelling of hole-
spin qubits and high-mobility devices based on group-IV
heterostructures.
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All authors Enrico Della Valle, Arianna Nigro, Miki Bonacci, Nicola Colonna, Andrea Hofmann, Michael Schüler, Nicola Marzari, Ilaria Zardo, Vladimir N. Strocov
Mesoscale and Nanoscale Physics
Daniel Dick, Florian Fuchs, Sibylle Gemming et al. (+1 more)
Local composition fluctuations in random
alloys become crucial when one or more dimensions are reduced to the nanoscale. Using extended Hückel theory, we study the
semiconductor random
alloy SiGe sandwiched between Si due to its relevance for transistor devices. We evaluate the effects of the
alloy composition, layer thickness, and local fluctuations of the Ge concentration on the band
alignment and the band gap. The results are compared with the finite
quantum well model. That model captures the essential physics and can act as a computationally faster alternative.
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All authors Daniel Dick, Florian Fuchs, Sibylle Gemming, Jörg Schuster
Mesoscale and Nanoscale Physics
Geometric blockade in a quantum dot coupled to two-dimensional and three dimensional electron gases
K. Yamada, M. Stopa, T. Hatano et al. (+4 more)
We fabricated a
quantum dot coupled laterally to a two-dimensional electron gas and vertically to a three-dimensional electron gas in order to investigate the eigenstate dependence of tunneling rate to these gases. We observed a bias-dependent “
geometric" current blockade. By tunneling via the asymmetric couplings, population inversion is induced and a dark metastable triplet state is revealed. The metastable state stops the current transport process, suppresses the current and asymmetrically widens the Coulomb diamond. By analyzing the current as a function of source-drain and gate voltage and the
magnetic field, we concluded that this effect is due to the
geometric shape of the electronic states in the dot and the current is limited by the tunneling rate due to the eigenstates, that is, artificial $\sigma$-coupling and $\pi$-coupling.
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All authors K. Yamada, M. Stopa, T. Hatano, T. Yamaguchi, T. Ota, Y. Tokura, S. Tarucha