Mesoscale and Nanoscale Physics · Cross-listed from math-ph
Dynamical delocalization in disordered 2D Chern insulators
Gianluca Panati, Constanza Rojas-Molina and Vincenzo Rossi
We show the existence of energies exhibiting dynamical delocalization in discrete 2D Chern
insulators perturbed by a random potential in a general setting. Our proof exploits two main features of the model: jumps in the integer value of the Chern character and continuity of averaged spectral projections in both energy and disorder parameters. This allows us to show robustness of the topological index in the presence of disorder, which, combined with existing methods to prove dynamical localization, allows us to provide detailed information on the phase diagram of the model. The novelty of our approach is that we are able to show dynamical delocalization in the disorder parameter, and not only in the energy parameter, which allows to prove Anderson metal-
insulator transition even when spectral gaps close due to the strength of disorder.
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Materials Science
Practical Insights to Thin Film Dewetting
Karim Gadelrab and Stefan Reimann-Zitz
Thin
liquid films exhibit rich instability and rupture dynamics that critically impact coating performance across many applications. In this work, we use the
lattice Boltzmann method (LBM) simulations within a lubrication-theory framework to systematically quantify how film thickness, surface energy, wettability, and intermolecular forces govern dewetting kinetics and long-time morphology. Master-curve scalings are identified for the time to dewet, revealing a strong power-law sensitivity to film thickness and a comparatively weak dependence on moderate variations in the contact angle. Following rupture, the film reaches a physically meaningful coverage plateau, whose magnitude correlates with material parameters and provides a practical window for morphological stabilization prior to coarsening. Long-time
evolution obeys classical coarsening scaling laws, with surface energy controlling domain density. These results demonstrate that lubrication-based models can deliver predictive design guidance for evaluating coating robustness and forming materials and surface engineering strategies. Source code is available at https://github.com/Zitzeronion/Swalbe.jl.
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Statistical Mechanics · Cross-listed from math-ph
The quantum group structure of long-range integrable deformations
Koen Schouten and Marius de Leeuw
Quantum integrable
spin chains are known to possess a large family of long-range deformations generated by the local, boost and bilocal operators. Although these deformations are well-understood on the level of the pairwise commuting charges, the underlying
quantum group structures had not yet been recognised. In this paper, we provide a
quantum group-theoretical description for the family of long-range deformations of arbitrary homogeneous Yang-Baxter integrable
spin chains up to first order in the deformation parameter. In particular, we show that the deformations are obtained via a twist of the algebraic structure of the underlying
quantum group. This twisting results in a generally non-associative
algebra that has a non-trivial Drinfeld associator. The Drinfeld associator is then shown to encode the information about the long-range interaction terms for the integrable
spin chain. Moreover, the deformed
quantum group is shown to contain a large perturbatively associative substructure, thus ensuring the perturbative integrability of the long-range model. The deformed
quantum group provides explicit expressions for the Lax operators and R-
matrices of the long-range deformed models, which manifestly satisfy the RLL relation and the Yang-Baxter equation up to first order in the deformation parameter. In order to derive the results, we introduce
algebra elements that we call the algebraic charge densities. As a side result, we provide a
conjecture for the explicit expressions of the undeformed charge densities in terms of these
algebra elements.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Structure-Aware Transformers for Learning Near-Optimal Trotter Orderings with System-Size Generalization in 1D Heisenberg Hamiltonians
Shamminuj Aktar, Reuben Tate and Stephan Eidenbenz
Trotterization is a standard approach for simulating
quantum time
evolution on
quantum computers, where the
Hamiltonian is split into local terms and each term is applied in sequence. The order of these terms affects the fidelity of the simulation when they do not commute, so the choice of ordering directly impacts the accuracy of the simulation. We study this problem for one-dimensional XXZ Heisenberg
Hamiltonians using a structured set of 24 candidate orderings derived from colorings of the
Hamiltonian's commutation graph and their group permutations. Finding the best candidate for large systems becomes prohibitive because fidelity evaluation is computationally expensive. In this work, we train a
transformer encoder on smaller systems to predict the best candidate ordering for larger systems directly from
Hamiltonian and Trotter-configuration features, without computing candidate fidelities at inference time. The model is trained on in-range systems of 3 to 14
qubits with 15-
qubit systems held out for validation. Experimental results show that the model reaches a mean test fidelity gap of 0.00115 relative to the best of the 24 candidates on out-of-range systems of 16 to 20
qubits. A training-size sweep further shows that generalization emerges once training includes systems up to L=8
qubits, with validation at L=9, and the gap continues to decrease as the training range grows. To our knowledge, this is the first application of a learned model to Trotter ordering, and it motivates future work on AI-guided Trotter ordering with generalization across
Hamiltonian families and system types.
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Statistical Mechanics · Cross-listed from physics.chem-ph
Stepping up enhanced rate calculations with EATR-flooding
Nicodemo Mazzaferro, Willmor J Pena Ccoa, Pilar Cossio et al. (+1 more)
Several recent methods have shown that it is possible to compute rate constants of very slow biomolecular processes using simulations where a time-dependent bias is added along one or several collective variables (CVs). We previously reported the exponential average time-dependent rate (EATR) method, which can improve upon these approaches by accounting for how efficiently the external biasing potential modifies the observed rate using a learned CV-quality factor $\gamma$. This results in more accurate rate estimates using the same data when biasing a suboptimal coordinate. However, as formulated EATR depended on the biasing potential varying over time to properly determine the biasing efficiency, which limits the method's applicability to quasi-static biasing schemes such as “flooding” or on-the-fly probability enhanced sampling (OPES). Here, we present the EATR-flooding approach, which generalizes our method by replacing the need for a time dependent bias by instead varying (stepping up) the strength of the biasing potential across multiple sets of simulations. We implement this approach as an open-source Python library, and demonstrate that this approach is accurate without substantial loss of efficiency compared to standard EATR for a coarse-grained
protein system, and also show good performance on a fully atomistic cavity-ligand model. Two additional appealing features of EATR-flooding are an internal check for over-biasing and the fact that only a single $\gamma$ parameter is predicted for a given choice of CVs, as compared to our earlier results where $\gamma$ empirically depended on biasing rate. Finally, we believe EATR-flooding applies not only to OPES simulations but more generally to CV biasing enhanced sampling approaches, making it broadly useful.
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All authors Nicodemo Mazzaferro, Willmor J Pena Ccoa, Pilar Cossio, Glen M. Hocky
Materials Science
First-Principles Thermodynamic Analysis of Ternary Chalcogenide Phase Change Materials
Felix Adams, Ichiro Takeuchi, Carlos Ríos Ocampo et al. (+1 more)
Chalcogenide phase-change materials (PCMs) are important for nonvolatile
memory and reconfigurable photonic technologies. The GeTe-Sb2Te3 system, commonly referred to as GST, is the best-known PCM family, but new PCMs are needed to broaden the accessible property space while retaining fast and reversible switching. Here, we propose a thermodynamic framework, motivated by Ostwald's rule, for understanding and identifying PCMs, since direct modeling of phase-transition dynamics is computationally expensive. Using first-principles calculations, we systematically evaluate the energetics of ternary chalcogenide mixtures and their polymorphs along binary-binary tie lines. By comparing ground-state and metastable structures, we assess phase stability, miscibility, and the likelihood of GST-like polymorph-mediated crystallization pathways across a broad range of ternary chalcogenide mixtures. The calculations reproduce known behavior in GST and related systems and identify several promising candidate mixtures with similar features. These results provide insight into why some PCM systems are more favorable than others and establish a thermodynamic framework for future PCM discovery.
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All authors Felix Adams, Ichiro Takeuchi, Carlos Ríos Ocampo, Yifei Mo
Materials Science
Contrasting Effects of Functionalization in Binary and Medium-Entropy MXene Coatings for Corrosion Protection
Aqsa Fayyaz, Ulises Martin Diaz, Jianyu Dai et al. (+2 more)
Developing scalable and environmentally benign anticorrosion coatings is critical for protecting steel infrastructure in chloride-rich environments. Here, a nacre-inspired multilayer epoxy coating reinforced with four MXene systems is investigated. This architecture forms a dense lamellar network that increases
diffusion tortuosity and introduces electroactive surfaces for ion interactions. Electrochemical impedance spectroscopy (EIS) confirms that the multilayer design increases coating resistance from ~103 to ~108 Ohm/cm2. A clear performance hierarchy was observed: P-(TiVCrMo)C3 > O-Ti3C2Tx > O-(TiVCrMo)C3 > P-Ti3C2Tx. Density functional theory (DFT) calculations reveal that P-Ti3C2 strongly adsorbs O2, indicating higher surface reactivity, while oxygen termination stabilizes the surface by partially passivating Ti sites. In contrast, P-(TiVCrMo)C3 exhibits strong adsorption of oxygen-containing species due to its multi-metal electronic structure, promoting the formation of protective
oxides. These results highlight the delicate balance of surface chemistry, electronic structure, and compositional
entropy in designing next-generation MXene-based anticorrosion coatings for marine and industrial environments.
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All authors Aqsa Fayyaz, Ulises Martin Diaz, Jianyu Dai, Homero Castaneda, Chenglin Wu
Superconductivity
Phase Stability of Superfluid $^{3}\mathrm{He}$ in Anisotropic Aerogel
J. W. Scott, D. Park, X. Yuan et al. (+1 more)
The A and B phases of superfluid 3 He have vector degrees of freedom that reflect their characteristic broken
symmetries, respectively
chiral and
spin-orbit rotation axes. Anisotropic disorder in the superfluid, imbibed in uniformly strained silica aerogel, orients these degrees of freedom, thereby affecting phase stability. These degrees of freedom have been found to spontaneously reorient at a field-independent transition temperature Tx , that can be accounted for with a temperature dependent anisotropic Ginzburg-Landau model.
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All authors J. W. Scott, D. Park, X. Yuan, W. P. Halperin
Superconductivity
Superconductivity-Enabled Conversion of Ferromagnetic Resonance into Standing Spin Waves
Ya. V. Turkin, N. G. Pugach, F. M. Maksimov et al. (+5 more)
Superconductors can transport
spin without Joule dissipation, yet their coherent coupling to short-wavelength
magnons in insulating magnets remains largely unexplored. Here we demonstrate experimentally and theoretically that a conventional diffusive
superconductor can enable the conversion of the uniform
ferromagnetic resonance (FMR) mode into perpendicular standing
spin waves (PSSWs) in an adjacent ferrimagnetic
insulator. In Bi-substituted iron-garnet/Nb
bilayers, the microwave transmission develops an additional resonance feature that appears only below the Nb superconducting transition temperature and lies close to the uniform FMR peak. A microscopic theory that self-consistently couples the quasiclassical Keldysh–Usadel description of the superconducting condensate to the Landau–Lifshitz–Gilbert dynamics shows that the conversion relies on two ingredients: (i) an interfacial
spin-transfer torque mediated by
spin-polarized triplet Cooper pairs and (ii) a depth-dependent effective field produced by Abrikosov
vortices (electromagnetic proximity). The resulting susceptibility reproduces the measured lineshapes and establishes superconductivity as an active control parameter for exchange standing-wave modes in
magnetic insulators.
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All authors Ya. V. Turkin, N. G. Pugach, F. M. Maksimov, A. S. Pakhomov, S. N. Polulyakh, V. S. Stolyarov, A. I. Chernov, V. I. Belotelov
Statistical Mechanics · Cross-listed from quant-ph
Long-lived local quantum coherences from hydrodynamic large deviations
Ewan McCulloch, J. Alexander Jacoby and Sarang Gopalakrishnan
We develop a framework to describe how
quantum coherences between distinct charge sectors evolve under generic charge-conserving dynamics. Our framework captures the nonperturbative interactions between
quantum coherences and hydrodynamic large deviations—i.e., rare “voids” of low charge
entropy. Conditional on surviving, the
quantum coherence and its surrounding void form a collective polaron-like object. In one dimension, even at infinite temperature, we show that the lifetime of coherences is parametrically enhanced because they bind to voids. We use our framework to address two fundamental questions about generic
quantum dynamics with a conserved charge. First, we argue that gapped Ruelle-Pollicott resonances are absent in the weak-noise limit, even in sectors of operator space that contain no hydrodynamic slow modes: instead, the spectral gap in all sectors vanishes nonperturbatively in the noise strength. Second, we compute the spacetime asymptotics of the dynamical single-particle Green's function, both in the weak-noise regime and in the absence of noise. In the noiseless case, we find that the void–coherence polaron undergoes subdiffusion, with an exponent we calculate. We support our general arguments with a microscopic derivation for random charge-conserving
circuits, as well as numerical evidence from tensor-network simulations.
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Statistical Mechanics
Dissipation Mechanisms and Dissipative Phase Transitions of two coupled Fully Connected Quantum Ising models
Bidyut Dey, Andrea Nava and Domenico Giuliano
We study dissipative phase transitions in a system of two coupled fully-connected
quantum Ising models interacting with an environment. The dynamics is governed by a Lindblad master equation combining coherent
unitary evolution and incoherent dissipative processes, where the
unitary part is described within a self-consistent mean-field framework effectively acting on the local
Hilbert space of two coupled
spins at each site. We analyze two fundamentally different classes of dissipators. In the first case, the jump operators are defined in the instantaneous eigenbasis of the mean-field
Hamiltonian and satisfy a detailed-balance condition. In this setting, the relaxation dynamics depends strongly on the quench protocol: a parametric quench of the
Hamiltonian leads to conventional relaxation, whereas a temperature quench gives rise to a dynamical phase transition characterized by nonanalytic behavior in time. Yet, in both cases, the system relaxes toward a steady state determined solely by the post-quench parameters and the bath temperature, which closely resembles a thermal Gibbs state of the mean-field
Hamiltonian. As a result, the dissipative phase transition occurs at a critical point consistent with the corresponding
equilibrium transition. In contrast, when the dissipators are realized via local
spin raising and lowering operators, the steady state is genuinely nonequilibrium, leading to a significantly richer phase diagram. In particular, for sufficiently strong system-bath coupling, we observe a reentrant phase featuring a
symmetry-broken region bounded by two continuous dissipative phase transitions. Our results evidence how the structure of dissipative processes controls the emergence of
equilibrium-like versus genuinely nonequilibrium critical behavior in open
quantum systems.
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Statistical Mechanics · Cross-listed from quant-ph
Nonlocal nonstabilizerness in free fermion models
Mario Collura, Benjamin Béri and Emanuele Tirrito
Nonlocal magic quantifies the irreducible nonstabilizerness of a bipartite
quantum state after optimizing over local basis changes. We study nonlocal magic for pure fermionic Gaussian states, and derive a simple closed-form
entanglement spectrum bound in terms of the singular values of the subsystem-restricted covariance
matrix. We
benchmark our result against simulated annealing over local Gaussian
unitary transformations, which supports optimality along the full local Gaussian orbit. For states drawn from the Gaussian Haar ensemble, we show that the average nonlocal magic is extensive and determine its thermodynamic limit using random
matrix theory for the appropriate circular
unitary ensemble. We also study Gaussian ground states, focusing on the Kitaev chain, and find that nonlocal magic is suppressed deep in both trivial and topological phases and peaks near the critical points. Finally, we investigate Gaussian
evolution via random
circuits and in quenches with the XY chain. For random
circuits, we find that nonlocal magic grows diffusively, while in the XY chain the XX limit reveals a striking separation between nonlocal magic and
entanglement.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Resolving spurious topological entanglement entropy in stabilizer codes
Peilun Han, Zijian Liang, Yifei Wang et al. (+3 more)
Topological
entanglement entropy (TEE) is a key diagnostic of long-range
entanglement in two-dimensional gapped phases of matter, but it can suffer from spurious contributions that overestimate the total
quantum dimension of the underlying topological order. In this work, we identify the microscopic origin of spurious TEE and introduce a concave partition for computing the Levin-Wen TEE of translation-invariant stabilizer codes of
prime-dimensional qudits. We rigorously prove that this prescription is free of spurious contributions. As a complementary probe, we study bivariate bicycle codes on a bipartite cylinder and show that the
entanglement entropy depends sensitively on the cylinder circumference, revealing topological frustration of the underlying anyons.
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All authors Peilun Han, Zijian Liang, Yifei Wang, Bowen Yang, Yingfei Gu, Yu-An Chen
Strongly Correlated Electrons
Local Current Algebra for the HK Universality Class
Yuting Bai and Philip W. Phillips
We show that a
Hamiltonian in terms of the local real-space currents obeying an $\mathfrak{su}_1(2)$ affine Lie
algebra eliminates the non-locality in the Hatsugai-Kohmoto model for a doped Mott
insulator. We establish this local correspondence through the Bjorken-Johnson-Low prescription for anomalous commutators. With this result, we show that the charge susceptibility computed from the current
Hamiltonian is identical to that with the elemental Fermionic fields. Consequently, the HK model is local in real space, though not in terms of the Fermionic fields, thereby eliminating the key criticism of this model and reinforcing the utility of current
algebras for strong interactions.
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Statistical Mechanics · Cross-listed from quant-ph
Non-Local Magic Resources for Fermionic Gaussian States
Daniele Iannotti, Beatrice Magni, Riccardo Cioli et al. (+2 more)
Entanglement and magic are fundamental resources that capture the complexity of
quantum many-body systems. Non-local magic isolates the irreducible nonstabilizerness intrinsically tied to
entanglement. However, evaluating this quantity generally requires a prohibitive minimization over the full
Hilbert space, making it computationally inaccessible beyond a few
qubits. Here, we overcome this bottleneck by establishing a closed-form expression for the non-local stabilizer
entropies of fermionic Gaussian states over local Gaussian
unitaries, which we prove at Rényi index $\alpha=2$ for arbitrary subsystem size, and which can be evaluated in
polynomial time directly from the
eigenvalues of the reduced Majorana covariance
matrix. We apply this framework to characterize fermionic non-local magic across diverse physical regimes: we derive an exact Page-like curve for typical random states, reveal logarithmic scaling at the
quantum critical point of the XY model, and establish a quasiparticle picture for magic generation during out-of-
equilibrium quantum quenches. Crucially, because our result relies solely on two-point correlation functions, it provides a scalable route for the experimental estimation of fermionic non-local magic in large-scale
quantum processors via fermionic shadow
tomography.
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All authors Daniele Iannotti, Beatrice Magni, Riccardo Cioli, Alioscia Hamma, Xhek Turkeshi
Strongly Correlated Electrons
Momentum-Space Entanglement Signatures and Spinon Breakdown in the $J_1$-$J_2$ Zig-Zag Heisenberg Chain
Tom Oeffner, Ludwig Bordfeldt, Andreas Feuerpfeil et al. (+5 more)
We investigate the resilience of spinon quasiparticles in the $J_1$-$J_2$ zig-zag
spin chain ($J_2>0$) from the viewpoint of momentum-space
entanglement. For small $J_2$, we show that deconfined spinons survive well past the
liquid-dimer transition before eventually collapsing towards the Majumdar-Ghosh point. In the highly frustrated zig-zag regime ($J_2 \gg |J_1|$), we model the system as two coupled Heisenberg chains and by
Fourier transforming each subchain individually, a framework we dub the double-spinon description. While continuum field theories predict that this decoupled phase is strictly unstable to any finite inter-chain coupling, our analysis reveals that the double-spinon description remains robust over an extensive parameter regime. Notably, we find a stark asymmetry in spinon stability reflecting the underlying renormalization group flow:
ferromagnetic coupling ($J_{1} < 0$) is marginally irrelevant and sustains fractionalization deep into the spiral phase, whereas
antiferromagnetic coupling ($J_{1} > 0$) is marginally relevant and drives confinement much earlier. The ultimate breakdown of this fractionalized description is driven by a continuum of inter-chain excitations which manifests itself as a sharp ground-state momentum shift distinct from macroscopic thermodynamic phase boundaries. Our results establish momentum cut
entanglement analysis as a tool to trace the quasiparticle resilience of spinons, as we show that treating the zig-zag Heisenberg chain as two coupled SU(2)$_1$ Wess-Zumino-Witten models provides a theoretical framework for strongly frustrated
quantum magnets applicable beyond the decoupled limit.
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All authors Tom Oeffner, Ludwig Bordfeldt, Andreas Feuerpfeil, Lukas Elter, Tobias Helbig, Tobias Hofmann, Martin Greiter, Ronny Thomale
Statistical Mechanics
Composite-Operator Scaling on Triadic Hypergraphs: Formation Transitions in Multi-Agent Architectures with Three-Body Coupling
Eduardo Salazar
We study phase transitions on dynamic triadic hypergraphs, in which a continuous formation field evolves under
stochastic Ginzburg–Landau dynamics with a cubic three-body coupling $g_\tau\phi_i\phi_j\phi_k$, while a discrete opinion variable $s_i\in\{-1,+1\}$ undergoes Kawasaki exchange under a
Hamiltonian with pairwise
alignment and an irreducible three-body energy $-\lambda_\tau\prod_{a\in\tau}s_a$. Near the formation critical point the cubic coupling is subleading and the transition remains continuous, controlled at leading order by a pairwise Ising baseline with renormalized coupling $J_{\rm eff}=J+\gamma w$. The dominant observable is the triadic formation correlator $\Psi_{\rm form}\equiv\langle\phi_i\phi_j\phi_k\rangle$, a $k=3$ composite operator built over the underlying $\mathbb{Z}_2$-symmetric order parameter. Composite-operator scaling yields the effective exponents $\beta_{\rm TF}=3/2$ and $\gamma_{\rm TF}=-1$. The susceptibility conjugate to $\Psi_{\rm form}$ vanishes at the critical temperature $T_c$ rather than diverging, in contrast to the divergence characterizing scalar (pairwise) order parameters. The exact partition function of the minimal triad on $\{-1,+1\}^3$ identifies a crossover scale $T^*=4J_{\rm eff}/\ln 3$. A field-theoretic two-point function argument reproduces the same vanishing susceptibility. Restoring the three-body coupling ($\lambda\neq0$) makes the transition first-order, with a critical endpoint at $\lambda=0$. The exponent relations $\beta_{\rm TF}=3\beta_{\rm Ising}$ and $\gamma_{\rm TF}=\gamma_{\rm Ising}-4\beta_{\rm Ising}$ hold exactly on dense hypergraphs via cluster decomposition, and the vanishing-susceptibility signature persists for $d\geq3$ but fails in $d=2$. A Mori–Zwanzig
memory kernel yields a continuously tunable dynamical exponent $z_{\rm TF}$, completing the composite-operator scaling regime.
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Materials Science · Cross-listed from physics.optics
Phase-Transition-Driven Hyperbolic Optical Response and Directional Polaritons in Epitaxial VO2 Thin Films
Maria Chiara Paolozzi, Annalisa D Arco, Ilaria Martinelli et al. (+10 more)
Optical anisotropy in crystalline solids enables direction-dependent light-matter interactions and underpins a variety of advanced photonic functionalities. In this context, Vanadium dioxide (VO2) represents a prototypical material that undergoes a reversible MIT near 67{\deg}C, accompanied by pronounced electronic, structural, and optical modifications. The MIT not only dramatically modifies the VO2 electrical conductivity but also reshapes its anisotropic optical response, making VO2 an exceptional platform for dynamically tunable photonic and optoelectronic devices. In this work, we investigate how the intrinsic crystalline anisotropy of VO2 induces a
hyperbolic optical behavior in the metallic rutile phase. We study two epitaxial VO2 thin films of different thicknesses grown on (110) oriented MgF2 substrates. Broadband polarized spectroscopic measurements, spanning the infrared to UV spectral range, are employed to independently investigate the optical response in both the monoclinic and rutile phases. From these measurements, we extract the optical conductivity and the dielectric function, revealing a pronounced anisotropy in the rutile metallic phase, with an enhanced free-carrier response along the rutile c axis. Our data show that, within a narrow near-infrared spectral window, the real parts of the dielectric tensor components along the two principal axes acquire opposite signs, indicating the emergence of a
hyperbolic type-II dispersion. The
hyperbolic response is quantitatively evaluated through the quality factor and the degree of dielectric anisotropy, enabling a systematic assessment of VO2 as a thermally switchable,
hyperbolic optical medium. These findings expand the understanding of anisotropy-driven optical phenomena in phase-change materials and highlight VO2 thin films as a promising platform for tunable and reconfigurable photonic applications.
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All authors Maria Chiara Paolozzi, Annalisa D Arco, Ilaria Martinelli, Lorenzo Mosesso, Jacopo Sera, Alessandro D Elia, Augusto Marcelli, Yingxue Chen, Chongwen Zou, Maria Cristina Larciprete, Marco Centini, Stefano Lupi, Salvatore Macis
Materials Science
Thin film synthesis of SrZn2P2 with SrI2 post-annealing for enhanced crystallinity and optoelectronic quality
Sita Dugu, Shaham Quadir, Christopher P. Muzzillo et al. (+11 more)
Ternary Zintl phosphides are promising light-absorbing
semiconductors for thin-film optoelectronic applications, but strategies for controlling their microstructure and optoelectronic quality remain underexplored. Here, we report the synthesis of phase-pure SrZn2P2 thin films using
radio-frequency co-sputtering in a PH3 + Ar atmosphere and investigate the impact of post-growth processing on their structural and optical properties. Grazing-incidence X-ray scattering and Raman spectroscopy confirm the formation of crystalline SrZn2P2 films over a finite compositional window. Optical measurements reveal strong absorption near the direct-band-gap energy (~1.8 eV) and near-band-edge photoluminescence. Further, we have studied the effects of chemically compatible halide-assisted annealing. It is found that SrI2 treatments lead to pronounced grain growth and reduced diffraction peak broadening while preserving phase purity, in contrast to rapid thermal or forming-gas annealing. Notably, annealing with SrI2 at 450 {\deg}C significantly enhances both the intensity and spatial uniformity of the photoluminescence, thus connecting the observed microstructural consolidation with improved radiative recombination. Our study demonstrates that halide-assisted annealing provides an effective pathway for microstructural control in SrZn2P2 thin films and highlights a generalizable processing strategy for advancing Zintl phosphide
semiconductors toward optoelectronic applications.
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All authors Sita Dugu, Shaham Quadir, Christopher P. Muzzillo, Zhenkun Yuan, Smitakshi Goswami, Xiaojing Hao, Jialiang Huang, Guillermo Esparza, Baptiste Julien, David Fenning, Jifeng Liu, Geoffroy Hautier, Andriy Zakutayev, Sage R. Bauers
Mesoscale and Nanoscale Physics
Large quantum dot energy level shifts in anomalous photon-assisted tunneling
Jared Benson, C. E. Sturner, A. R. Huffman et al. (+12 more)
Orbital energy splittings are important
quantum dot parameters for the operation of hole
spin qubits. They are known to depend on the lateral confinement of the
quantum dots. However, when changing top, plunger gate voltages, which are the typical control parameter for
qubit applications, such energy splitting changes are typically negligible, both as measured in experiment and as assumed in effective theories. Here, we study the singlet-triplet (ST) splittings, which depend on the orbital splittings, of a double
quantum dot (DQD) in a Ge/SiGe
heterostructure using
photon-assisted tunneling (PAT) and pulsed-gate spectroscopy. We find that the ST splittings have a surprising, strong dependence on the top gate voltages, leading to anomalous PAT measurements. We combine data from both measurements in a model that well describes the linear gate-voltage dependence of the ST splittings. Finally, we show that the ST splittings of the two dots exhibit similar linear gate-voltage dependences when the device is retuned such that their ratio is significantly different.
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All authors Jared Benson, C. E. Sturner, A. R. Huffman, Sanghyeok Park, Valentin John, Brighton X. Coe, Tyler J. Kovach, Stefan D. Oosterhout, Lucas E. A. Stehouwer, Francesco Borsoi, Giordano Scappucci, Menno Veldhorst, Benjamin D. Woods, Mark Friesen, M. A. Eriksson
Strongly Correlated Electrons
Schwinger-Boson Mean-Field Study of the Anisotropic Kagome Antiferromagnet
Sankha Subhra Bakshi, Brandon B. Le, Seung-Hun Lee et al. (+1 more)
We investigate the effect of spatial exchange anisotropy on the
spin-$1/2$ kagome antiferromagnet using Schwinger-
boson mean-field theory. The anisotropy is introduced by strengthening the Heisenberg exchange along one set of nearest-neighbor bonds relative to the other two, and is controlled by a parameter $\delta$ that measures the deviation from the isotropic limit. Incorporating the reduced
lattice symmetry, we construct the corresponding projective-
symmetry-group ansätze and focus on representative $0$- and $\pi$-flux states connected to the conventional $q=0$ and $\sqrt{3}\times\sqrt{3}$ kagome states. We find that anisotropy predominantly reconstructs the low-energy spinon sector, leading to a strong softening of the lowest spinon branch and a downward shift of the two-spinon continuum. At sufficiently large $\delta$, the spinon gap closes at ansatz-dependent values, signaling an instability toward spinon condensation and the onset of
magnetic order. From the soft Bogoliubov eigenmodes, we reconstruct the associated incipient
spin textures and show that the resulting
magnetic orders are intrinsically anisotropic, with suppressed moments on strongly coupled bonds and enhanced moments on more weakly connected sites. These results provide a microscopic picture of how exchange anisotropy drives the transition from kagome
spin-
liquid states to
magnetic order, and offer a framework for interpreting recent experiments on anisotropic kagome materials, particularly titanium-based
spin-$1/2$ compounds.
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All authors Sankha Subhra Bakshi, Brandon B. Le, Seung-Hun Lee, Gia-Wei Chern
Quantum Gases
Quantum scattering of droplets by wells and barriers in one-dimensional Bose-Bose mixtures
Sherzod R. Otajonov, Uktambek R. Eshimbetov, Bakhram A. Umarov et al. (+1 more)
We investigate, both analytically and numerically, the scattering of quasi-one-dimensional
quantum droplets from Pöschl-Teller potential wells and barriers. For attractive wells, we find a sharp transition between complete reflection and transmission at a critical incident velocity for both small and large flat-top droplets. The scattering interactions differ: small,
soliton-like droplets form a spatially symmetric trapped mode at the critical velocity, showing their compressibility and coherence characteristics, while large droplets develop a spatially asymmetric trapped state, revealing incompressibility and internal structure. The critical velocity depends non-monotonically on atom number: it rises in the small, compressible-droplet regime, falls in the incompressible, flat-top regime, and turns at the crossover point. We also show that the reflectionless well generates a $\pi$-phase shift, strongly altering droplet-droplet collisions relative to free space. The persistence of a confined mode after collisions between trapped and incident droplets depends sensitively on their relative phase. For the repulsive barrier, we identify regimes of complete reflection, partial return, and full transmission, depending on incident velocity, barrier height, and particle number. Our predictions match direct numerical simulations in all cases.
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All authors Sherzod R. Otajonov, Uktambek R. Eshimbetov, Bakhram A. Umarov, Fatkhulla Kh. Abdullaev
Materials Science
Resolving growth-induced off-stoichiometry in AgCrSe$_2$ single crystals
Felix Eder, Zeno Maesen, Yurii Skourski et al. (+3 more)
The layered delafossite-like antiferromagnet AgCrSe$_2$ is a superionic conductor at high temperatures and has been reported to exhibit anomalous
Hall behavior and Kondo physics at low temperatures. These extraordinary transport properties have been established almost exclusively on single
crystals grown by chemical vapor transport, raising questions about the role of growth-induced off-stoichiometry. Using elemental analysis, single-
crystal X-ray diffraction, and magnetization measurements, we show that such
crystals are indeed systematically off-stoichiometric, with a general composition of Ag$_{1-x}$Cr(Se$_{2-y}$Cl$_y$) ($x \approx y \approx 0.08$) arising from the use of CrCl$_3$ as a transport
agent. This off-stoichiometry manifests in altered
magnetic properties, most notably a suppressed Néel temperature of 46\,K compared to 58\,K in stoichiometric polycrystalline samples prepared by solid-state synthesis. By optimizing an Ag/Se self-flux growth method, we obtained large single
crystals of AgCrSe$_2$ that recover the
magnetic transition temperature and saturation field of stoichiometric powder samples. These results establish self-flux growth as a route to high-quality stoichiometric AgCrSe$_2$ single
crystals and provide a reliable platform for reassessing whether the reported anomalous transport phenomena are intrinsic or arise from off-stoichiometry.
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All authors Felix Eder, Zeno Maesen, Yurii Skourski, Enrico Giannini, Oksana Zaharko, Fabian O. von Rohr
Statistical Mechanics · Cross-listed from quant-ph
A Gaussian asymmetry measure
Riccardo Travaglino and Pasquale Calabrese
The study of
Entanglement Asymmetry has emerged in recent years as a powerful tool to characterise the
symmetry properties of
quantum states in relation to a given charge operator through the lens of
entanglement. While extremely powerful and general, the standard definition of asymmetry introduces significant non-Gaussian features in free-fermionic systems, leading to certain analytical limitations. In this work, we introduce an asymmetry measure that remains strictly within the Gaussian
manifold and analyse its properties. In particular, we show that it quantifies the minimal distance between a Gaussian state and the
manifold of symmetric Gaussian states. We further demonstrate that this measure captures the established dynamical signatures of
entanglement asymmetry, such as the Mpemba effect,
symmetry restoration, and the lack thereof. The Gaussian structure allows these novel asymmetry measures to be computed exactly using correlation
matrix techniques, and to be described asymptotically through the quasiparticle picture. We also comment on the possibility of using charge fluctuations to characterise the asymmetry of a Gaussian state.
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Materials Science · Cross-listed from physics.bio-ph
Can we teach generative artificial intelligence the design language of engineered living materials?
Andrés Díaz Lantada, José A. Yáñez, William Solórzano-Requejo et al. (+1 more)
This study presents a versatile ontology and a useful codification scheme for describing all kinds of engineered living materials (ELMs). The different components of the ontology, namely: families according to the taxonomy for ELMs, industrial applications and synthesis or processing methods, are systematically organized, enumerated, classified, codified and explained. The methodic application of the ontology to a set of 100 relevant examples of ELMs helps to demonstrate its utility and adaptability to many different types of ELMs with a wide range of industrial applications and obtained through numerous synthesis and processing methods. This proves that the developed ontology and codification schemes, with the glossary provided to support its implementation and application, can serve as a comprehensive classification tool for the emergent field of ELMs. Furthermore, the usability of the ELMs ontology and codification by a generative artificial intelligence (AI) is explored and validated by different means, checking that both natural
language and the codification are understandable for describing ELMs, verifying that the generative AI adequately codifies examples of ELMs according to the ontology, and validating the synergic applicability of the ontology and codification with generative AI tools for illustrating novel ELMs and supporting their conceptual design. This study is expected to provide a universal
language to facilitate communication in the ELMs field and to foster the discovery of new ELMs and related innovations, hoping it may accelerate scientific and technological discoveries.
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All authors Andrés Díaz Lantada, José A. Yáñez, William Solórzano-Requejo, Monsur Islam
Strongly Correlated Electrons
Correlation-Driven Ballistic Exciton Expansion in a Moiré Bose-Fermi Mixture
Shibin Deng, Jonas M. Peterson, Maximilian Hauer et al. (+8 more)
Moiré superlattices of transition-metal dichalcogenides (TMDs) host strongly interacting Bose-
Fermi mixtures in which bosonic
excitons coexist with correlated electron
lattices. Using ultrafast, time- and energy-resolved photoluminescence (PL) microscopy, we show that strong
exciton-electron and
exciton-
exciton repulsion can enable ballistic
exciton transport in a WSe$_2$/WS$_2$ heterobilayer. This ballistic transport is energy selective: repulsive interactions populate higher-energy moiré
exciton bands, including the doubly occupied
exciton state XX and the
exciton-electron co-localized state Xe, exhibiting mean-squared displacement (MSD) with a quadratic time dependence, MSD $\propto t^2$. Transport in the Xe band is jointly governed by
exciton and electron correlations.
Exciton correlations suppress relaxation into the lower-energy localized
exciton state, while generalized Wigner-
crystal (GWC) order at fractional electron fillings enhances Auger recombination and the group velocity of the ballistic expansion. A two-dimensional Bose-
Fermi Hubbard model solved using time-dependent mean-field methods qualitatively reproduces the measured
exciton transport and time-dependent response. It further confirms that strong cross-species interactions allow the electron
crystal to perforate the
exciton Mott background, enhancing
exciton motion. Our results establish moiré TMDs as highly tunable platforms for realizing strongly interacting Bose-
Fermi mixtures.
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All authors Shibin Deng, Jonas M. Peterson, Maximilian Hauer, Jonas Reimann, Heonjoon Park, Ammon Fischer, Takashi Taniguchi, Kenji Watanabe, Xiaodong Xu, Dante M. Kennes, Libai Huang
Superconductivity
Non-local Tunneling Spectroscopy of Inelastic Quasiparticle Relaxation in Superconducting 1-D Wires
Kevin M. Ryan, Detlef Beckmann and Venkat Chandrasekhar
Non-local conductance experiments using tunnel junctions can provide valuable spectroscopic information on both the transport and relaxation of quasiparticles in
superconductors, as these techniques directly probe the quasiparticle charge and energy imbalance even at mK temperatures. In this work, we employ mesoscopic three terminal Cu and Al NIS devices to study non-local quasiparticle transport over length-scales on the order of the superconducting coherence length in this regime. Via a dual-bias scheme, which utilizes detector biases both above and below the superconducting gap, we are able to extract the effect of quasiparticle energy imbalance via its impact on the self consistent pair potential by
symmetry considerations. We observe non-local conductance features due to pair-breaking which are anti-symmetric with respect to the polarity of the voltage bias, with a sharp onset during single electron tunneling at energies around $3\Delta$. We compare these findings with quasiclassical simulations including inelastic effects to obtain estimates of the energy dependent inelastic scattering time. In addition, we demonstrate kinetic effects due to a large applied supercurrent which can also be captured in this formalism and decomposed with respect to the particle-hole
symmetry and supercurrent direction, and discuss further opportunities for the advancement of this method.
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Superconductivity
Engineering superconductivity on the surface of Weyl semimetals
Riccardo Vocaturo and Mattia Trama
Ten years after the experimental discovery of Weyl semimetals, theoretical and experimental work has pointed to the possibility of realizing surface-only superconductivity at relatively high temperatures in these materials. A consensus is developing that this unusual form of superconductivity is supported by surface electronic states unique to Weyl semimetals, known as
Fermi arcs. In this work, we show that the topological protection of these exotic states can be exploited to engineer high critical temperatures. Motivated by reports of van Hove singularities on the surface of PtBi$_2$-the first Weyl semimetal in which surface superconductivity was unequivocally linked to its
Fermi arcs-we demonstrate how such singularities can be engineered through the deposition of a suitable additional layer. We find that the critical temperature becomes extremely sensitive to the exact value of the chemical potential, and values as large as 20 times the bulk $T_c$ can be achieved. More generally, our results demonstrate how topological protection can be exploited to manipulate surface electronic states, thereby opening experimentally accessible routes toward engineering high-temperature two-dimensional superconductivity and other exotic phases.
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Statistical Mechanics
Largest eigenvalue and top eigenvector statistics of large Euclidean random matrices
Pasquale Casaburi and Pierpaolo Vivo
Euclidean random
matrices arise in a wide range of physical systems where interactions are determined by spatial configurations, including disordered media and cooperative phenomena in atomic ensembles. Unlike classical random
matrix ensembles, their entries are strongly correlated through the geometry of the underlying random points, making their analytical treatment challenging. While global spectral properties such as the spectral density are relatively well understood, much less is known about extremal
eigenvalues and the associated eigenvectors, despite their central role in applications. Here we address the problem of characterising the largest
eigenvalue and the corresponding top eigenvector of large Euclidean random
matrices with a generic symmetric kernel. For vectors in any dimension $d\geq 1$ drawn independently from a common distribution, we show that both quantities can be computed within a unified replica-based framework. In the large-$N$ limit, the replica saddle-point equations reduce to an
eigenvalue problem for a Fredholm integral operator determined by the kernel and by the underlying distribution. We then specialise this general formulation to the quadratic distance kernel, for which the Fredholm problem reduces to a finite set of $d+2$ self-consistent equations. In this case, we obtain an explicit expression for the average largest
eigenvalue, fully determined by low-order moments of the underlying distribution, and an analytical characterisation of the density of the top eigenvector's components. We further perform extensive numerical simulations that confirm these predictions. More broadly, our work provides a general framework to access extremal spectral properties of Euclidean random
matrices.
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Statistical Mechanics · Cross-listed from physics.flu-dyn
Constitutive Modelling of Korteweg Fluids Using Liu's Method
Zagorka Matić, Srboljub Simić and Peter Ván
The paper studies constitutive modelling of Korteweg fluids. Thermodynamic consistency, i.e. compatibility with
entropy balance law, is achieved using Liu's method of multipliers. Appropriate constitutive assumptions facilitated inclusion of the capillary effects in the specific
entropy. Korteweg stresses are derived from the
equilibrium conditions – vanishing of the
entropy production and its minimization in
equilibrium. Material parameter in Korteweg stresses is allowed to depend on temperature, which turns out to be consistent with kinetic-theory results and leads to cross-coupling of mechanical and thermal effects. The generalized Gibbs' relation, which inherits the capillary effects, is derived as consequence, which is a peculiar feature of the Liu's method.
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