Mesoscale and Nanoscale Physics
Quantum transfer in high-root topological insulators
G. F. Moreira, A. Lykholat, R. G. Dias et al. (+1 more)
This paper focuses on the
quantum state transfer in a one-dimensional (1D) high-root topological
insulator (HRTI) with an arbitrary number of domains. We present the possibility of having multiple transfer processes in the same model due to the existence of various edge states in distinct energy gaps, which may benefit recent (de)multiplexing technologies. We also derived the relations between transfer times of different root models and different gaps in the same model. We show how the exponential decay in transfer time caused by the fragmentation of a parent chain into domains can be generalized to its higher-root versions while maintaining a high transfer fidelity, and how the increasing number of domain wall states leads to a higher transfer fidelity against a general disorder regime due to the topological protection inherited from the parent model.
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All authors G. F. Moreira, A. Lykholat, R. G. Dias, A. M. Marques
Materials Science
First principles characterization of spinterfaces between magnetic Cobaltocene molecule and 2D magnets (CrI$_3$, Fe$_3$GeTe$_2$)
Nikola Machacova and Biplab Sanyal
In this paper, we examine the properties of
spin-polarized interfaces consisting of single-molecule magnet bis(cyclopentadienyl)cobalt(II) (cobaltocene) and two-dimensional
magnetic materials, semiconducting CrI$_3$ and metallic Fe$_3$GeTe$_2$, using first-principles density functional theory based calculations. Our calculated adsorption energies indicate the stability of these hetero-interfaces with the observation of hybridization of electronic states across the interface.
Magnetic exchange interaction parameters have been obtained from both total energy differences and the Liechtenstein-Katsnelson-Antropov-Gubanov (LKAG) formalism in the basis of maximally localized Wannier functions (MLWFs). Analysis of these parameters shows a strong directional anisotropy in the
magnetic substrate-molecule interaction in agreement with the nature of orbital hybridization. Additionally, possible exchange mechanisms are proposed based on orbital-resolved exchange and hopping parameters. We also show that the molecular adsorption may enhance the intralayer exchange interactions, with some exchange parameters reaching up to a 3-fold increase in magnitude compared to the freestanding case. Finally, we observe a 100 %
spin polarization at the
Fermi level in the cobaltocene/CrI$_3$ interface, which makes it particularly promising for
spin-transport applications.
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Statistical Mechanics · Cross-listed from math.DS
A Mathematical Framework for Linear Response Theory for Nonautonomous Systems
Stefano Galatolo and Valerio Lucarini
Linear Response theory aims to predict how added forcing alters the statistical properties of a system. This has been predominantly studied for autonomous dynamical systems, yet many systems in the physical, natural, and social sciences are inherently nonautonomous. In such settings, one would like to understand how the system's time-dependent statistical properties change when additional infinitesimal forcings are applied. This question is of clear practical relevance, but from a rigorous mathematical viewpoint it has been addressed only for a few specific classes of systems and perturbations. Here we provide a rigorous linear response theory for a rather general class of deterministic and random nonautonomous systems satisfying a specific set of assumptions that are the counterpart of the standard assumptions used in the autonomous setting. A central ingredient is rapid loss of
memory along the nonautonomous
evolution. Our main strategy is to reformulate the sequential dynamics as a fixed-point problem for a global transfer operator acting on an extended sequence space of measures. This yields explicit and readily implementable causal response formulas for predicting the effect of small perturbations on time-dependent statistical states. We illustrate the theory on two representative classes: sequential compositions of expanding maps and sequential compositions of noisy random maps. We also establish linear response for reflected Euler-Maruyama discretizations of dissipative nonautonomous
stochastic differential equations with nondegenerate additive Gaussian noise, on fixed compact domains. As a physical application, we study the response of a Ghil-Sellers
climate energy balance model, discretized in latitude and time to a time-dependent perturbation of the greenhouse parameter.
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Materials Science
Theoretical investigation of the photovoltaic properties of MgSnN$_{2}$ for multi-junction solar cells
Issam Mahraj, Mossab Oublal and Andrzej Ptok
The orthorhombic
crystal structure of the MgSnN$_2$ compound with Pna2$_1$
symmetry has been investigated as a low-cost, non-toxic material for photovoltaic (PV) applications using density functional theory (DFT) and spectroscopic limited maximum efficiency (SLME) calculations. A detailed analysis of the electronic and optical properties was performed using the mBJ semilocal exchange functional. The bandgap of MgSnN$_2$ is found to be 2.45 eV. SLME photovoltaic analysis suggests that a thin film of MgSnN$_2$ with a thickness of 2 $\mu$m can reach an efficiency of 13.17% at room temperature. This efficiency was further improved through the simulation of a multi-junction device, where the tandem configuration increased the efficiency from 12.80% (single-junction) to 22.42%. Furthermore, introducing cation disorder can further reduce the bandgap, enhancing its suitability for
solar cell applications.
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Mesoscale and Nanoscale Physics
Energy renormalizations of resident carriers and excitons in transition metal dichalcogenide monolayers
Dinh Van Tuan, Junghwan Kim and Hanan Dery
Energy renormalizations of resident carriers and
excitons are studied theoretically, and compared with recent experiments of electrostatically-doped WSe$_2$ monolayers. The calculated energy renormalization of resident carriers, subjected to strong out-of-plane
magnetic field, reveals the importance of dynamical screening in transition metal dichalcogenides. The energy renormalization of tightly bound
excitons is analyzed through the exchange interaction between the electron (or hole) component of the
exciton and resident carriers that share the same
spin and valley
quantum numbers. Our theory explains the weak energy shift of excitonic resonances despite the strong energy renormalization of resident carriers. We identify the dependence of the energy renormalization on the envelope function of a tightly-bound
exciton, showing that unlike free electron-hole pairs, this energy renormalization is not the added renormalizations of a resident electron and resident hole.
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Mesoscale and Nanoscale Physics
Ultrastrong Coupling and Coherent Dynamics in a Gate-Tunable Transmon Qubit
I. Casal Iglesias, F. J. Matute-Cañadas, G. O. Steffensen et al. (+10 more)
Ultrastrong light-matter coupling (USC) gives access to exotic
quantum phenomena and promises faster
quantum gates, yet coherent time-domain control in this regime remains largely unexplored. Here, we realize USC in a hybrid system consisting of an InAs nanowire-based gatemon
qubit coupled to a superconducting resonator. Spectroscopy reveals an avoided crossing that cannot be captured by the Jaynes-Cummings (JC) model, as well as
photon-number-dependent transitions whose energies deviate markedly from the JC ladder expected in the strong coupling regime. Beyond demonstrating USC, we achieve time-resolved coherent control of the
qubit and measure coherence times comparable to gatemons operating outside the USC regime. These results establish that hybrid
semiconductor-
superconductor qubits can retain coherent control in USC and provide a platform for exploring
quantum dynamics and device concepts in this regime.
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All authors I. Casal Iglesias, F. J. Matute-Cañadas, G. O. Steffensen, A. Ibabe, L. Splitthoff, T. Kanne, J. Nygard, V. Rollano, D. Granados, A. Gomez, R. Aguado, A. Levy Yeyati, E. J. H. Lee
Materials Science
Auxetic Response in Two-Dimensional MXenes with Atomically Defined Perforations
Hossein Darban
Recent advances in nanoscale fabrication enable atomic-scale manipulation of two-dimensional (2D) materials by introducing engineered pores and perforations. This provides new opportunities to tailor functional properties of 2D materials for applications such as selective ion transport, desalination membranes, and molecular filtration. Despite this progress, the auxetic mechanical behavior of perforated 2D materials has received little
attention. In this work, large-scale reactive molecular dynamics (MD) simulations, validated against experimental measurements and first-principles calculations, are employed to investigate the mechanical response of perforated monolayer titanium-based MXene metamaterials. Architectures containing rectangular perforations with straight ligaments and sinusoidally curved ligaments are systematically examined under uniaxial tension and compression over a range of
geometric parameters and temperatures, from the onset of deformation to fracture. The results demonstrate that MXene metamaterials exhibit a tunable negative Poisson's ratio (NPR), which can be controlled through the perforation geometry and surface termination. Atomistic stress analysis reveals alternating in-plane shear stresses at the junctions that induce rotational deformation of the ligaments. This rotating-junction mechanism is coupled with out-of-plane deflections arising from the low bending
rigidity of atomically thin materials, producing complex three-dimensional deformations. Comparison with
graphene metamaterials indicates that the perforation geometry governs qualitative auxetic trends, whereas intrinsic material properties determine quantitative responses. These findings identify MXenes as a versatile candidate for the design of tunable 2D mechanical metamaterials and provide atomistic insight into the interplay between geometry, bending
rigidity, and auxetic deformation mechanisms.
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Mesoscale and Nanoscale Physics
Spin transport analysis for a spin pseudovalve-type L_l/SC/L_r trilayer for L = {FeCr, Fe, Co, NiFe, Ni} and SC = {GaSb, InSb, InAs, GaAs, ZnSe}
Julián A. Zúñiga, Arles V. Gil Rebaza and Diego F. Coral
In this work, we present a theoretical study of
spin transport in a trilayer pseudospin-valve (PSV)
heterostructure composed of electrode (L_l)/
insulator/electrode (L_r). The insulating layer corrresponds to a
semiconductor (SC) with a zinc-blende
crystal structure from the III-V (GaSb, InSb, InAs, and GaAs) or the II-VI (ZnSe), while the electrodes are
ferromagnetic materials L_j = {FeCr, Fe, Co, NiFe, Ni}. This combination yields 125 possible PSV configurations. The theoretical model implemented is based on the approach proposed by J. C. Slonczewski. In our approach, the exchange splitting in the
ferromagnetic materials and the
spin-orbit coupling (SOC) of the Dresselhaus and Rashba types in the
semiconductors are included, allowing control of the wave vector associated with the
spin states. The tunnel magnetoresistance (TMR) is calculated at low temperature as a function of the
semiconductor thickness, parameterized with respect to the crystallographic axis that favors the magnetization direction in the
ferromagnetic electrodes, within the Landauer–Büttiker formalism in the single-channel regime. The results show that the TMR reaches its maximum value independently of the relative orientation between the magnetization vector and the crystallographic direction. The most efficient configuration corresponds to Fe_{90}Cr_{10}/GaSb/Fe_{90}Cr_{10}, with a TMR value of 83.60%. Furthermore, the Dresselhaus SOC contributes more significantly to the TMR than the Rashba SOC. Finally, the TMR varies when the electrodes L_j are permuted, due to differences in their
Fermi energies. The obtained results are compared with previous studies reported in the literature based on alternative theoretical frameworks or assumptions, showing good agreement.
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Materials Science
Tailoring Emergent Magnetic Moment in La$_{0.7}$Sr$_{0.3}$MnO$_3$-Bi$_2$Te$_3$ Heterostructures via Interfacial Reconstructions
Damian Brzozowski, Yu Liu, Øyvind Finnseth et al. (+6 more)
We report emergent
magnetic behavior in
heterostructures composed of (111)-oriented La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO) and (00$l$)-oriented Bi$_2$Te$_3$ (BT), controlled by interfacial reconstructions. When BT is deposited directly onto LSMO, an intermediate interfacial layer forms between the two materials. Polarized
Neutron Reflectometry modeling reveals that this reconstructed region stabilizes a secondary magnetically ordered phase that is coupled to the underlying
ferromagnetic LSMO layer. As a consequence, the
heterostructures exhibit unconventional self-crossing
magnetic hysteresis loops at room temperature, characterized by a reversal of the net magnetization at low applied fields. In contrast, the introduction of a tellurium seed layer results in a sharper LSMO-BT interface, while preserving the anomalous hysteresis behavior and enhancing the saturation magnetization. Element-specific X-ray absorption spectroscopy suggests that the emergent
magnetic phase originates from the chemical reconstruction of manganese species. These results demonstrate that interface engineering in
magnetic oxide-topological
insulator heterostructures provides a pathway to control emergent
magnetic coupling and emergent
magnetic states in
oxide-topological
insulator heterostructures.
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All authors Damian Brzozowski, Yu Liu, Øyvind Finnseth, Egil Y. Tokle, Andrew J. Caruana, Christy J. Kinane, Alexander J. Grutter, Dennis G. Meier, Ingrid Hallsteinsen
Statistical Mechanics
Sorting by Resetting
Bart Cleuren and Ralf Eichhorn
A novel paradigm for sorting is introduced, based upon resetting. Using simple examples, we demonstrate that sorting is achieved by resetting the velocity component(s) or orientation of the particles, rather than position. The objects to be sorted are microparticles, modeled as suspended and spatially extended Brownian particles. This sorting-by-resetting scheme illustrates that
stochastic resetting can create non-
equilibrium conditions which enable tasks forbidden at thermodynamic
equilibrium.
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Statistical Mechanics
Level 2.5 large deviations and uncertainty relations for self-interacting jump processes: tilting constructions and the emergence of time-scale separation
Francesco Coghi and Juan P. Garrahan
Self-interacting jump processes (SIJPs) describe systems with non-Markovian
stochastic dynamics in which transition rates depend on empirical observables of the process, which gives rise to long-range
memory and feedback. We derive the “level-2.5” large deviation (LD) principle governing the joint fluctuations of empirical occupation measure and the flux
matrix for a broad class of SIJPs with general functional dependence on an empirical observable. The derivation is based on an exponential tilting construction and reveals a separation between a faster timescale of the microscopic dynamics and a slower timescale of the
memory-driven
evolution of transition rates, which is expressed through an exponentially discounted LD rate functional. Using this variational framework, we derive kinetic and thermodynamic uncertainty relations that extend classical Markovian bounds to non-Markovian systems, and illustrate their performance with simple examples.
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Statistical Mechanics
Dynamic scaling near the Kasteleyn transition in spin ice: critical relaxation of monopoles and strings following a field quench
Sukla Pal and Stephen Powell
We study dynamics in classical
spin ice following a
magnetic field quench to close to the Kasteleyn transition, using Monte Carlo simulations and dynamic scaling theory to characterize the relaxation of the magnetization and the density of
magnetic monopoles. We have previously argued that this dynamics can be described in terms of seeding and growth of strings of flipped
spins, and our results here demonstrate that a solvable
stochastic model based on independent strings correctly describes the relaxation as well as the distribution of string lengths within the critical scaling regime near the transition. We also show how generalized scaling forms capture the behavior over a broader range of monopole densities and provide a clear understanding of the breakdown of the scaling picture further from the critical point.
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Mesoscale and Nanoscale Physics
Programmable, Spontaneous Superlattice Memory in a Monolayer Topological Insulator
Jian Tang, Thomas Siyuan Ding, Shuhan Ding et al. (+24 more)
Memory is a foundational concept across disciplines, from neurobiology and electronics to artificial intelligence and
quantum gravity. In materials,
memory effects typically arise from ferroic orders, such as ferroelectricity and ferromagnetism, where information is stored in charge or
spin degrees of freedom. Here, we report a surprising discovery of a nonvolatile superlattice
memory effect in monolayer TaIrTe4, a dual
quantum spin Hall insulator, where information is encoded through sharply contrasting
lattice periodicities. In particular, in a pristine monolayer, we observe the spontaneous emergence of a long-period superlattice that can be programmed ON and OFF in a nonvolatile manner by electrostatic tuning of low-energy electronic states. This switching toggles the system between two structural configurations with unit
cell areas differing by nearly two orders of magnitude. Mechanistically, our results reveal two independent and distinct instabilities, one in the
lattice and the other in the QSH electrons, which are coupled, leading to electrostatic control of
lattice configurations with nonvolatile
memory. This finding is enabled by combining linear and nonlinear transport measurements, Raman spectroscopy, and scanning tunneling microscopy, which probe complementary aspects of the underlying orders. Remarkably, this nonvolatile
memory effect stabilizes a spontaneous superlattice with a periodicity on the few-nanometer scale that remains robust across a wide doping range, persists over days, and survives above 70 K. Combined with the QSH
topology, this stability offers a promising route to nonvolatile
memory control of topological flat bands and their filling enabled
quantum states. Our preliminary data indeed show the emergence of new insulating states at fractional superlattice fillings, which can be clearly switched ON and OFF together with the superlattice.
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All authors Jian Tang, Thomas Siyuan Ding, Shuhan Ding, Jiangxu Li, Changjiang Yi, Tianxing Tang, Zumeng Huang, Xuehao Wu, Zhiheng Huang, Birender Singh, Tiema Qian, Vsevolod Belosevich, Mingyang Guo, Anyuan Gao, Nikolai Peshcherenko, Zhe Sun, Mohamed Shehabeldin, Kenji Watanabe, Takashi Taniguchi, Abhay N. Pasupathy, Claudia Felser, Kenneth S. Burch, Ni Ni, Yao Wang, Yang Zhang, Su-Yang Xu, Qiong Ma
Materials Science
Electrically switchable ferron upconversion in a van der Waals ferroelectric
Sujan Subedi, Wuzhang Fang, Fan Fei et al. (+7 more)
Nonlinear phononics provides a powerful ultrafast route to control
lattice excitations, enabling access to hidden
quantum orders, phononic computing, and
quantum transduction. However, dynamic control of anharmonic
phonon interactions remains limited, as these interactions are typically fixed by the
equilibrium crystal lattice and lack external tunability. Emergent ferrons in ferroelectrics, which are collective oscillations of the spontaneous electric polarization, may offer a promising platform to overcome this limitation by combining intrinsic phononic nonlinearity with direct electrical control of the ferroelectric order parameter. Here we report electrically controllable nonlinear ferron upconversion in the van der Waals ferroelectric NbOI2. We show that resonant THz excitation of a 3.1 THz ferron drives coherent upconversion to a 7.0 THz optical
phonon. Using two-dimensional THz spectroscopy, we directly resolve off-diagonal coupling features and establish the nonlinear upconversion pathway. Supported by first-principles calculations and analytical modeling, we identify the microscopic origin as a cubic anharmonic
lattice coupling. Importantly, in situ electric-field switching enables nonvolatile control of both the ferron dynamics and the associated upconversion process. The phase reversal and hysteretic behavior across the coercive fields establish that the ferron-mediated nonlinear phononic interaction is strongly dependent on the underlying ferroelectric order parameter. These results introduce ferron upconversion as a new and universal regime of nonlinear phononics in ferroelectrics and establish an electrically programmable platform for coherent
lattice control, paving the way for ferronic information processing and
quantum phononic transduction.
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All authors Sujan Subedi, Wuzhang Fang, Fan Fei, Zixin Zhai, Jack P. Rollins, Carter Fox, Alaina Drew, Bing Lv, Yuan Ping, Jun Xiao
Strongly Correlated Electrons
Matrix Product States for Modulated Topological Phases: Crystalline Equivalence Principle and Lieb-Schultz-Mattis Constraints
Shang-Qiang Ning, Hiromi Ebisu and Ho Tat Lam
Modulated
symmetries are internal
symmetries that act in a spatially non-uniform manner. Consequently, when a modulated
symmetry $G_{\text{int}}$ is combined with a spatial
symmetry $G_{\text{sp}}$, the total
symmetry group takes the form of a semidirect product $G=G_{\text{int}}\rtimes G_{\text{sp}}$. Using
matrix product states, we classify topological phases protected by modulated
symmetries together with spatial
symmetries in one spatial dimension. We show that these modulated
symmetry-protected topological (SPT) phases are classified by $H^{2}(G,U(1)_s)$, in agreement with the crystalline equivalence principle, which states that SPT phases protected by
symmetries involving spatial elements are in one-to-one correspondence with internal SPT phases protected by the same
symmetries, viewed as acting internally. Furthermore, we provide a
matrix product state derivation of the Lyndon-Hochschild-Serre spectral sequence for the corresponding internal SPT phases, which enables us to construct an explicit correspondence between modulated SPT phases and internal SPT phases. As applications of this classification, we prove a Lieb-Schultz-Mattis (LSM)
theorem for modulated
symmetries that forbids the existence of symmetric short-ranged entangled ground state, as well as an SPT-LSM constraint that enforces nontrivial
entanglement in the SPT ground state. Finally, we use the classification to establish a similar LSM-type constraints for non-invertible Kramers-Wannier reflection
symmetries.
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Mesoscale and Nanoscale Physics
Tailoring Corner States and Exceptional Points in Altermagnets
Xiao-Ming Zhao, Cui-Xian Guo, Xin-Ran Ma et al. (+2 more)
Altermagnets (AMs) exhibit vanishing net magnetization but strong momentum-dependent
spin splitting enforced by
crystal symmetry. Here, we explore the non-Hermitian effects in dissipative two-dimensional AMs. We show that
symmetry-compliant dissipation naturally induces an imaginary staggered exchange field, driving a NH topological phase transition absent in conventional antiferromagnets. In the topologically nontrivial phase, hybrid skin-topological modes driven by altermagnetic d-wave anisotropy emerge, as captured by the
chiral skin effect framework. In the gapless phase, we elucidate the creation and annihilation dynamics of exceptional points. Crucially, we analytically prove via the transfer
matrix method that corner states are deterministically controlled by the boundary sublattice termination. Owing to the
symmetry constraints and the robustness of
chiral states, these findings hold universally across all topological AMs. A general framework is established for controlling topological corner states, offering a new strategy for designing
magnetic materials with tailored non-Hermitian properties.
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All authors Xiao-Ming Zhao, Cui-Xian Guo, Xin-Ran Ma, Xiao-Ran Wang, Su-Peng Kou
Soft Condensed Matter
Deciphering Molecular Charge Anisotropy: the Case of Antibody Solutions
Fabrizio Camerin, Susana Marin-Aguilar, Anna Stradner et al. (+2 more)
Electrostatic interactions fundamentally govern the structure, stability, and dynamics of charged (bio)matter, yet the impact of heterogeneous and anisotropic charge distributions on the behavior of
protein solutions remains elusive. Here, we introduce a versatile multiscale framework that directly connects molecular-level electrostatics to collective properties via a colloid-inspired coarse-grained modeling combined with neural network-assisted optimization. Using monoclonal antibodies as model system, our inverse design approach identifies charge patterns capable of reliably reproducing experimental structure factors, osmotic compressibility and collective
diffusion coefficients in a wide region of
protein concentrations. Close inspection of our data further uncovers how specific physical features and spatial arrangements of localized charge patches significantly influence the solution structure. This transferable strategy provides a predictive pathway to decode and control charge-driven interactions in complex biomolecules and, more generally, in heterogeneously-charged soft matter systems, with immediate relevance to
protein formulation and biomaterials engineering.
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All authors Fabrizio Camerin, Susana Marin-Aguilar, Anna Stradner, Peter Schurtenberger, Emanuela Zaccarelli
Statistical Mechanics
Logarithmic growth of operator entanglement in a clean non-integrable circuit
Mao Tian Tan and Tomaž Prosen
We study a so-called semi-ergodic brickwork dual-
unitary circuits where, in the infinite volume limit, the two-point correlation functions of single-site operators exhibit ergodic behavior along one light ray and non-ergodic behavior along the other light ray. Here, however, we study intermediate and long-time dynamics of a system in a finite, large volume. Under such dynamics, the Heisenberg
evolution of a single traceless single-site operator lies within a restricted subspace, and this time
evolution can be mapped to a simpler problem of a single qutrit scattering with a bunch of
qubits sequentially. Despite the model being non-integrable and free from any quenched disorder, the operator
entanglement grows at most logarithmic in time, contrary to prior expectations. The auto-correlation function can be written in terms of a sum of products of $SO(3)$
matrices, allowing for a random
matrix prediction for the auto-correlation function at late times. The operator size distribution also becomes bimodal at certain times, displaying intermediate behavior between chaotic and free systems.
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Statistical Mechanics · Cross-listed from hep-th
Towards a Refinement of Krylov Complexity: Scrambling, Classical Operator Growth and Replicas
Hugo A. Camargo, Yichao Fu, Keun-Young Kim et al. (+1 more)
We propose and test logarithmic Krylov (logK) complexity, an operator growth measure akin to Krylov complexity defined through a replica approach, as a viable probe of early-time operator scrambling without false positives. In finite-dimensional
quantum systems, such as the Lipkin–Meshkov–Glick (LMG) model and the mixed-field Ising model at the chaotic point, we provide numerical evidence that logK-complexity discriminates between genuine and saddle-dominated scrambling at early times, correctly avoiding the exponential contribution coming from the unstable saddle in the former case, and closely tracking the conventional Krylov complexity in the latter. In integrable
quantum systems admitting infinite-dimensional Krylov subspaces, such as the SYK$_{2}$ model and the
quantum inverted harmonic oscillator, we show that by modifying the Krylov spreading operator, obtained through generalizing the analytic continuation procedure in the replica trick, the logK complexity can be refined to capture the integrable properties of the theories. We supplement these analyses by extending the Krylov formalism in classical dynamical systems and defining classical versions of these operator growth measures, showing that the false positives arising from unstable saddles in classical phase space are non-existent.
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All authors Hugo A. Camargo, Yichao Fu, Keun-Young Kim, Yeong Han Park
Superconductivity
Crossover and Critical Behavior in the Layered XY Model
Roman Kracht, Andrea Trombettoni, Ilaria Maccari et al. (+1 more)
Motivated by the interplay between 2D and 3D scaling signatures observed in unconventional layered
superconductors, we present a systematic Monte Carlo study of the three-dimensional classical XY model with anisotropic in-plane $J_\parallel$ and inter-plane $J_\perp$ couplings. Our study includes very small values of the system anisotropy $\Delta=J_\perp /J_\parallel$ not studied before, and focuses on characterizing the crossover from quasi-2D topological scaling to genuine 3D critical behavior. The numerical results for the critical temperature unambiguously reveal a logarithmic scaling with $\Delta$, directly related to the topological scaling in the 2D limit. Despite the 3D nature of the layered XY criticality, topological scaling signatures survive up to system sizes comparable to the crossover length $\ell_J$, which diverges at small $\Delta$ with a scaling behavior reminiscent of the Berezinskii-Kosterlitz-Thouless (BKT) transition. This shows that genuine 3D
symmetry-breaking behavior emerges only at exceedingly large system sizes when the anisotropy is very strong. Our results indicate that new experimental evidence is required to clarify the extent to which the critical signatures observed in layered strongly correlated materials are shaped by their pronounced anisotropy.
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All authors Roman Kracht, Andrea Trombettoni, Ilaria Maccari, Nicolò Defenu
Quantum Gases
Rotation-triggered Kelvin-Helmholtz and counter-superflow instabilities in a three-component Bose-Einstein condensate
Susovan Giri, Arpana Saboo, Hari Sadhan Ghosh et al. (+2 more)
Interfacial hydrodynamic instabilities in multicomponent superfluids provide a versatile platform to explore nonequilibrium
quantum dynamics beyond classical fluid analogues. We study dynamical interfacial instabilities in a quasi-two-dimensional three-component Bose-Einstein condensate confined in a harmonic trap, where rotation is applied selectively to the intermediate component to generate controlled relative motion at two interfaces. This selective rotation protocol enables the independent tuning of shear and counterflow across the inner and outer boundaries, allowing direct control over the nature and strength of the resulting instability mechanisms. Three regimes are examined: Kelvin-Helmholtz instability in the strongly immiscible limit, counter-superflow instability in the partially miscible regime, and a parameter window where both unstable mechanisms are present. The onset condition for the Kelvin-Helmholtz instability is derived using a hydrodynamic pressure-balance approach, and the subsequent nonlinear
evolution is obtained from time-dependent Gross-Pitaevskii simulations. A Bogoliubov-de Gennes analysis is performed to identify the dominant unstable modes excited during the dynamical
evolution of the system. The conniving features of the collective excitations and their spatial structures have been consistent with the density modulations observed during the dynamics. The results demonstrate that the presence of two interfaces and tunable intercomponent interactions in a three-component condensate modifies the instability mechanisms relative to binary mixtures and provides a controlled parameter regime to study multicomponent
quantum hydrodynamics.
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All authors Susovan Giri, Arpana Saboo, Hari Sadhan Ghosh, Vipin, Sonjoy Majumder
Strongly Correlated Electrons
Matrix Product States for Modulated Symmetries: SPT, LSM, and Beyond
Amogh Anakru, Linhao Li, Sarvesh Srinivasan et al. (+1 more)
Matrix product states (MPS) provide a powerful framework for characterizing one-dimensional
symmetry-protected topological (SPT) phases of matter and for formulating Lieb-Schultz-Mattis (LSM)-type constraints. Here we generalize the MPS formalism to translationally invariant systems with general modulated
symmetries. We show that the standard
symmetry "push-through" condition for conventional global
symmetry must be revised to account for
symmetry modulation, and we derive the appropriate generalized condition. Using this generalized push-through structure, we classify one-dimensional SPT phases with modulated
symmetries and formulate LSM-type constraints within the same MPS-based framework.
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All authors Amogh Anakru, Linhao Li, Sarvesh Srinivasan, Zhen Bi
Statistical Mechanics · Cross-listed from physics.flu-dyn
Reduction of Triadic Interactions Suppresses Intermittency and Anomalous Dissipation in Turbulence
Anikat Kankaria, Ritwik Mukherjee, Sugan Durai Murugan et al. (+2 more)
We investigate how the defining statistical features of three-dimensional
turbulence respond to systematic reductions of the
Fourier-space triadic interaction network. Using direct numerical simulations of both fractally and homogeneously decimated Navier-Stokes dynamics, we show that progressive thinning of the set of active modes leads to a systematic suppression of intermittency and, most strikingly, to the vanishing of the mean dissipation rate in the large-Reynolds-number limit. Structure-function exponents collapse onto their dimensional values, the multifractal singularity spectrum contracts, and the analyticity width extracted from the exponential spectral tail increases monotonically with decimation-each indicating a substantial regularization of the velocity field. Together, these results provide direct evidence that anomalous dissipation in incompressible
turbulence is not a generic property of the Navier-Stokes equations, but instead requires the full combinatorial richness of their triadic nonlinear interactions.
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All authors Anikat Kankaria, Ritwik Mukherjee, Sugan Durai Murugan, Marco Edoardo Rosti, Samriddhi Sankar Ray
Strongly Correlated Electrons
Interface magnetic coupling and magnetization dynamic of La$_{2/3}$Sr$_{1/3}$MnO$_3$ single layer and (La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$)$_n$ (n = 1, 5) superlattice on SrTiO$_3$(001) substrate
Ilyas Noor Bhatti, Rachna Chaurasia, Kazi Rumanna Rahman et al. (+3 more)
In this work, we investigate the structural,
magnetic, and microwave
magnetic dynamics of multilayered \([{\rm LSMO}/{\rm SRO}]_n\)
heterostructures \((n = 1 \text{ and } 5)\) grown on SrTiO\(_3\) (001) substrates. X-ray diffraction confirms high crystallinity and atomically sharp interfaces.
Magnetic measurements reveal strong interfacial
magnetic coupling, with a distinct two-step magnetization switching observed in the \(n = 5\)
heterostructure, while this feature is significantly suppressed in the \(n = 1\) structure.
Ferromagnetic resonance (FMR) analysis shows a broad linewidth, pronounced positive
magnetic anisotropy, and Gilbert damping on the order of \(10^{-2}\), with damping decreasing as the number of multilayer repetitions increases. These observations demonstrate that Ru–Mn exchange coupling at the interface critically governs the
magnetic response and dynamic behavior of the system. The tunable switching and damping properties highlight such
oxide heterointerfaces as promising platforms for exploring
spin textures,
magnetic domain behavior, and room-temperature spintronic applications.
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All authors Ilyas Noor Bhatti, Rachna Chaurasia, Kazi Rumanna Rahman, Sukhendu Sadhukhan, Amantulla Mansuri, Imtiaz Noor Bhatti
Materials Science
Photoferroelectric Coupling and Polarization-Controlled Interfacial Band Modulation in van der Waal Compound CuInP2S6
Subhashree Chatterjee, Rabindra Basnet, Rajeev Nepal et al. (+1 more)
Understanding how optical excitation couples with polarization and interfacial electrostatics in van der Waals (vdW) ferroelectrics (FEs) is essential for the development of light-programmable nanoelectronic and optoelectronic devices. Here, we present direct nanoscale evidence of photoferroionic coupling in the vdW FE
semiconductor CuInP2S6 (CIPS), where optical excitation jointly modulates electronic band bending, FE switching, and Cu+ ionic relaxation. The use of correlated Kelvin probe force microscopy, piezoresponse force microscopy, and conductive atomic force microscopy under above-bandgap illumination reveals illumination-induced enhancement of surface work function, persistent surface photovoltage, reduced coercive field, and positive imprint shifts. These effects arise from synergistic photocarrier redistribution and slow Cu+ migration that reshape interfacial depletion widths and internal electric fields. Illumination-assisted barrier lowering further enhances carrier injection and produces sweep-rate-dependent ferroionic transport hysteresis. Our results establish photoferroionic coupling as the governing mechanism for light-controlled band modulation and polarization stability in CIPS, providing a nanoscale framework for designing light-addressable FE
memories, optoelectronic switches, and neuromorphic devices based on layered ferroionic materials.
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All authors Subhashree Chatterjee, Rabindra Basnet, Rajeev Nepal, Ramesh C. Budhani
Materials Science
Ferroelectric $p$-wave magnets
Jan Priessnitz, Anna Birk Hellenes, Riccardo Comin et al. (+1 more)
Couplings between ferroelectric and
magnetic orders offer promising routes toward low-dissipation electronics. However, such couplings are notably rare, largely due to the poor compatibility between insulating band structures and ferromagnetism. Here, we study a different strategy: we identify previously overlooked time-reversal-symmetric $p$- and $f$-wave
spin-polarized insulating electronic states in ferroelectrics with noncollinear
magnetic sublattices. We show that combining
spin and
magnetic group theory enables a systematic classification of the origin of polar
symmetry breaking. We distinguish crystallographic, exchange-, or
spin-orbit-driven mechanisms. Furthermore, we identify more than 50 candidate materials. Using first-principles calculations, we demonstrate a pristine, time-reversal-symmetric $p$-wave
spin-polarized electronic structure in the well-known multiferroic $\mathrm{GdMn_2O_5}$. We further show that its $p$-wave order can be switched electrically, opening alternative paths toward spintronic and multiferroic functionalities in this class of materials.
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All authors Jan Priessnitz, Anna Birk Hellenes, Riccardo Comin, Libor Šmejkal
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Active Quantum Particles from Engineered Dissipation
Jeanne Gipouloux, Matteo Brunelli, Leticia Cugliandolo et al. (+2 more)
We introduce and characterize different models for an active
quantum particle where activity arises from engineered dissipation– specifically, from a suitably coupled nonequilibrium environment. These include a model of a particle moving on a
lattice with coherent and dissipative hopping, as well as
quantum generalizations of well-studied models of active behavior, such as the active Ornstein-Uhlenbeck process, run-and-tumble dynamics, and the active Brownian particle. Despite the different microscopic mechanisms at play, we show that all these models display key features of active motion. Notably, we observe a crossover from diffusive to active-diffusive behavior at long times, leading to an effective Péclet number, as well as a strong sensitivity to boundary conditions which, in our open
quantum system context, arises from the Liouville skin effect. We discuss the role of
quantum fluctuations and experimental realizations with superconducting
circuits or cold gases, closing with perspectives for many-body effects in
quantum active matter.
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All authors Jeanne Gipouloux, Matteo Brunelli, Leticia Cugliandolo, Rosario Fazio, Marco Schirò
Quantum Gases
Probing Coherent Many-Body Spin Dynamics in a Molecular Tweezer Array Quantum Simulator
Yukai Lu, Connor M. Holland, Callum L. Welsh et al. (+2 more)
Models of interacting
quantum spins are used in many areas of physics ranging from the study of magnetism and strongly correlated materials to
quantum sensing. In this work, we study coherent many-body dynamics of interacting
spin models realized using polar molecules trapped in rearrangeable optical tweezer arrays. Specifically, we encode
quantum spins in long-lived rotational states and use the electric dipolar interaction between molecules, together with Floquet
Hamiltonian engineering, to realize $1/r^3$ XXZ and XYZ models. We microscopically probe several types of coherent dynamics in these models, including
quantum walks of single
spin excitations, the emergence of
magnon bound states, and coherent creation and annihilation of
magnon pairs. Our results establish molecular tweezer arrays as a new
quantum simulation platform for interacting
quantum spin models.
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All authors Yukai Lu, Connor M. Holland, Callum L. Welsh, Xing-Yan Chen, Lawrence W. Cheuk
Strongly Correlated Electrons · Cross-listed from quant-ph
Utility-scale quantum computational chemistry
Davide Castaldo and Markus Reiher
Chemistry and materials science are widely regarded as potential killer application fields for
quantum hardware. While the dream of unlocking unprecedented simulation capabilities remains compelling,
quantum algorithm development must adapt to the evolving constraints of the emerging
quantum hardware in order to accomplish any advantage for the computational chemistry practice. At the same time, the continuous advancement of classical wavefunction-theory methods narrows the window for a broad
quantum advantage. Here, we explore potential benefits of
quantum computation from the broader perspective of utility-scale applications. We argue that
quantum algorithms need not only enable accurate calculations for a few challenging, that is strongly correlated, molecular structures, that might be hard to describe with traditional methods. Instead, they must also support the practical integration of
quantum-accelerated computations into high-throughput pipelines for routine calculations on arbitrary molecules, ultimately delivering a tangible value to society.
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Statistical Mechanics
Maximum entropy distributions of wavefunctions at thermal equilibrium
Jacob T. Willson, Henrik J. Heelweg and Adam P. Willard
Statistical mechanics reveals that the properties of a macroscopic physical system emerge as an average over an ensemble of statistically independent microscopic subsystems, each occupying a specific microstate. In the study of
quantum systems, these microstates can be chosen to correspond to the pure state wavefunctions of individual
quantum systems. However, the physical principles that govern the distribution of a pure state wavefunction ensemble, even under conditions of thermal
equilibrium, are not well established. For instance, the canonical Boltzmann distribution cannot be applied to wavefunctions because they lack a definite energy. In this manuscript, we present a maximum
entropy principle for the
quantum wavefunction ensemble at thermal
equilibrium, the so-called Scrooge ensemble. We highlight that a constraint on the energy expectation value, or even the shape of the associated eigenstate distribution, fails to yield a valid
equilibrium state. We find that in addition to these constraints, one must also constrain the measurement
entropy to be equal to the Rényi divergence of the ensemble with respect to the Gibbs state, indicating that the Rényi divergence may have uninvestigated physical importance to thermal
equilibrium in
quantum systems.
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