Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Shu Long, Hong-Sen Yin, Chao Yang et al. (+3 more)
We establish a direct connection between
Hamiltonian band
topology and the Liouvillian spectral winding of open
quantum systems with quadratic dissipations. This allows the band
topology to act as a knob for controlling Liouvillian
topology and corresponding non-
equilibrium dynamics. In particular, we show analytically that, for
chiral Hamiltonians under sublattice-unidirectional
chiral dissipation, the Liouvillian spectral winding depends on the
Hamiltonian solely through its band winding number, thereby enabling direct band-topological control of the Liouvillian skin effect. We further identify two distinguished coherent and incoherent Liouvillian skin effects therein: the former hosts a band-topological dark state of the
Hamiltonian, whereas the latter yields a mixed steady state driven by dissipative nonreciprocity. Our results establish a systematic framework for topological control of spectral and spatial organization in open
quantum systems and provide a unified perspective on
topology in
Hamiltonian and dissipative dynamics.
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All authors Shu Long, Hong-Sen Yin, Chao Yang, Sen Mu, Jia-Wei Zhang, Linhu Li
Mesoscale and Nanoscale Physics
The Anyon Zeno Effect
David F. Mross
Two anyons encircling each other acquire a quantized braiding phase that is independent of their spatial separation. We show that detecting this phase in a fractional
quantum Hall interference experiment results in a
quantum Zeno effect: a localized anyon is trapped by constant observation from a stream of anyons supplied by the measurement current. Interferometers with an embedded antidot are ideal for accessing the Zeno regime, where the bare tunneling rate of localized anyons is much lower than the measurement rate. The Zeno-suppressed tunneling rate of the trapped anyon depends on the braiding phase and the transmission of the
quantum point contacts. Our primary prediction is that the autocorrelation time of the conductance through the interferometer increases with the bias current. This effect may be used to experimentally control the anyon dynamics, in particular to increase the lifetime of localized anyons.
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Statistical Mechanics · Cross-listed from quant-ph
Partial Reversibility and Counterdiabatic Driving in Nearly Integrable Systems
Rohan Banerjee, Shahyad Khamnei, Anatoli Polkovnikov et al. (+1 more)
Adiabatic (or reversible) processes are the key concept unifying our understanding of thermodynamics and dynamical systems. Reversibility in the thermodynamic sense is understood as
entropy-preserving processes, such as in the idealized Carnot engine, whereas in integrable dynamical systems it is understood as the conservation of the action variables. Between these two idealized limits, however, things are much less clear. In this work, we study several toy models to assess the extent to which reversible processes are even possible in this regime. We then explore how the dissipative losses resulting from rapidly driving these kinds of systems can be fought by approximate counterdiabatic driving. Finally, we provide numerical evidence that much of the phenomenology should be the same for
quantum many-body systems with large degeneracy in the presence of integrability breaking perturbations.
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All authors Rohan Banerjee, Shahyad Khamnei, Anatoli Polkovnikov, Stewart Morawetz
Superconductivity
Inhomogeneous superconductivity in (001), (110), and (111) KTaO$_3$ two-dimensional electronic gases: effect of electronic confinement on the transition temperature
Mattia Trama, Roberta Citro and Carmine Antonio Perroni
Experimental observations on KTaO$_3$ superconductivity report widely different critical temperatures with a clear hierarchy among different crystallographic orientations. Accounting for the first time for spatial confinement, we connect the inhomogeneous superconducting order parameter with the spatial extent of the two-dimensional electron gas. We reproduce the observed hierarchy within a unified framework, based on a self-consistent tight-binding slab model with local
spin-singlet $s$-wave pairing. The methods developed here can readily be extended to include more general interaction models, while still consistently including the characteristic spatial structure of the electron gas.
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Quantum Gases · Cross-listed from quant-ph
Taxonomy of integrable and ground-state solvable models: Jastrow wave functions on graphs and parent Hamiltonians
Nilanjan Sasmal and Adolfo del Campo
We introduce a family of many-body systems of distinguishable continuous-variable particles in which interparticle interactions are set by the adjacency
matrix of a graph. The ground-state wave function of such systems is of a generalized Jastrow form involving the product of pair-correlation functions over the edge set of the graph. These systems describe
quantum fluids when the graph is complete, and the pair function has a well-defined permutation
symmetry. In general, they provide the continuous-variable generalization of
spin systems on graphs, with broken permutation
symmetry. The corresponding parent
Hamiltonian is shown to include (a) two-body interactions determined by the graph adjacency
matrix and (b) three-body interactions over all possible 2-paths on the graph. Employing elements of graph theory, we chart the landscape of models, recovering known instances in the literature and providing numerous new examples of ground-state solvable models for which the system
Hamiltonian, ground-state wave function, and corresponding energy
eigenvalue are specified.
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Strongly Correlated Electrons
Tuning the magnetic properties of Kitaev materials via the antiferromagnetic proximity effect: Novel phases and application to an $\alpha$-RuCl$_3$/MnPS$_3$ bilayer
Pedro M. Cônsoli, Ezra Day-Roberts, Johannes Knolle et al. (+2 more)
In recent years, the increasing level of control over van der Waals (vdW)
heterostructures has opened new routes to tune the properties of
quantum materials. Motivated by these developments, we examine the potential consequences of interfacing a Kitaev honeycomb magnet, such as $\alpha$-RuCl$_3$, with a nearly
lattice-matched vdW antiferromagnet. By combining perturbation theory, exact diagonalization, and a classical energy-minimization method, we show that an effective staggered
magnetic field originating from the vdW antiferromagnet can drive a monolayer of a Kitaev material into various novel phases, including an antichiral Kitaev
spin liquid, a nonmagnetic nematic phase, and different types of skyrmion
crystals. We then apply first-principles simulations to assess the prospect of concretely realizing this setup in a heterobilayer of $\alpha$-RuCl$_3$ and the easy-axis antiferromagnet MnPS$_3$.
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All authors Pedro M. Cônsoli, Ezra Day-Roberts, Johannes Knolle, Antia S. Botana, Onur Erten
Mesoscale and Nanoscale Physics
Atomic-Scale Quantum Control of Single Spin Defects in a Two-Dimensional Semiconductor
Kwan Ho Au-Yeung, Wantong Huang, Johanna Matusche et al. (+15 more)
Individual
spin defects in solids are promising building blocks for
quantum technologies, but their deterministic creation, individual addressability, and operation near surfaces remain major challenges. Two-dimensional materials provide an attractive alternative, as their single-layer thickness enables direct atomic-scale access to defect states. Here, we demonstrate single-
spin control of solid-state defects in a two-dimensional
semiconductor by a combination of scanning tunneling microscopy and electron
spin resonance. We create and manipulate individual sulfur vacancies and carbon substitution defects in monolayer molybdenum disulfide and characterize their
spin dynamics, including coherent control, at the single-defect level. Using atomic manipulation, we further engineer and probe
spin-
spin interactions between defect pairs. Our results demonstrate deterministic creation, addressability, coherent manipulation, and controlled coupling of individual
spin defects within a single experimental platform. This establishes atomically engineered
spin defects in two-dimensional
semiconductors as a versatile class of controllable solid-state
quantum systems and opens a route towards tailored
quantum sensing experiments.
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All authors Kwan Ho Au-Yeung, Wantong Huang, Johanna Matusche, Paul Greule, Jonas Arnold, Lovis Hardeweg, Máté Stark, Luise Renz, Affan Safeer, Daniel Jansen, Thomas Michely, Jeison Fischer, Wolfgang Wernsdorfer, Christoph Sürgers, Hannu-Pekka Komsa, Johannes Schwenk, Wouter Jolie, Philip Willke
Mesoscale and Nanoscale Physics
Phononic enhancement and detection of hidden spin-nematicity and dynamics in quantum magnets
Junyu Tang, Hong-hao Song and Gang v. Chen
The
spin nematic phase, characterized by long-range order of
spin quadrupole moments in the absence of dipolar magnetism, presents a significant challenge for conventional experimental detection. We propose a novel method to detect this elusive order in
quantum magnets with an illustration in the
spin-1 triangular
lattice Mott
insulator. By integrating out the
phonon degrees of freedom, we obtain a phase diagram with substantially enlarged regions for the
spin-nematic and
spin-nematic-supersolid phases. We then demonstrate that through the
spin-
lattice coupling, the emergence of
spin nematic order imprints a distinctive signature onto the
phonon spectra, providing a clear spectroscopic signature for the quadrupolar order accessible via Raman or inelastic X-ray scattering. Our formalism offers a direct and powerful method to uncover the hidden
spin nematicity, opening a new pathway for diagnosing multipolar orders in
quantum magnets.
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Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Quantum jumps in open cavity optomechanics and Liouvillian versus Hamiltonian exceptional points
Aritra Ghosh and M. Bhattacharya
Exceptional points, where two or more eigenstates of a non-Hermitian system coalesce, are now of interest across many fields of physics, from the perspective of open-system dynamics, sensing, nonreciprocal transport, and topological phase transitions. In this work, we investigate exceptional points in cavity optomechanics, a platform of interest to diverse communities working on gravitational-wave detection, macroscopic
quantum mechanics,
quantum transduction, etc. Specifically, we clarify the role of
quantum jumps in making a clear distinction between Liouvillian and
Hamiltonian exceptional points in optomechanical systems. While the Liouvillian exceptional point arises from the unconditional Lindblad dynamics and is independent of the
phonon-bath temperature, the
Hamiltonian exceptional point emerges from the conditional no-jump
evolution and acquires a thermal shift due to an enhanced conditional damping. Employing the thermofield formalism, we derive a unified spectral framework that interpolates between these regimes via an analytical hybrid-Liouvillian description. Remarkably, in the weak-
quantum-jump regime, the exceptional point is perturbed only at the second order, highlighting the robustness of the
Hamiltonian exceptional point under small hybrid perturbations. Our work reveals a continuous family of hybrid exceptional points, clarifies the operational and physical differences between the conditional and unconditional dissipative dynamics in optomechanical systems, and provides a probe for thermal baths.
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Disordered Systems and Neural Networks
Thermal activation drives a finite-size crossover from scale-free to runaway avalanches in amorphous solids
Gieberth Rodriguez-Lopez and Ezequiel E. Ferrero
We investigate thermal avalanche dynamics in amorphous solids using elastoplastic models with local activation rules and no external driving. Dynamical heterogeneities, quantified through persistence measurements and the associated four-point susceptibility $\chi_4$, reveal the emergence of correlated spatiotemporal rearrangements as temperature is varied. As temperature increases, avalanche statistics evolve from scale-free behavior with exponential cutoffs to regimes dominated by system-spanning runaway events. We identify a system-size-dependent critical temperature $T_c(L)$ that separates intermittent avalanche dynamics from thermally assisted flow, where self-sustained avalanches transiently fluidize the system. We show that $T_c(L)$ decreases algebraically with increasing system size, suggesting that in the thermodynamic limit arbitrarily small but finite temperatures may destabilize the intermittent regime. The relation between avalanche size and duration resembles that in sheared systems, whereas the statistics of minimal distances to yielding reveal a temperature-driven reorganization of marginal stability absent in strictly driven overdamped dynamics. Our results demonstrate that thermal activation alone can generate a finite-size-controlled instability scale in disordered elastic media.
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Strongly Correlated Electrons
Chiral Weyl-Kondo semimetals and hexagonal heavy fermion systems
Kuan-Sen Lin, Yuan Fang, Henrique Fabrelli et al. (+7 more)
Strong correlation, in concert with
symmetry and
topology, engenders novel gapless phases of matter, though only a tip of the iceberg has been seen. An exemplary framework is provided by Weyl-Kondo semimetals, in which Weyl
fermions develop through crystalline
symmetry constraints on the emergent low-energy heavy-
fermion excitations. This paradigm has opened up new opportunities to explore correlated
topologies without a noninteracting counterpart, but fully realizing this potential requires a large base of candidate materials. Here we confront the challenge on both fronts by studying heavy
fermion systems with hexagonal space groups. This family contains a large number of
chiral nonsymmorphic
crystal structures that promote Weyl degeneracies and, in addition, feature
geometric frustration in the $f$-electron magnetism. Our calculations for the heavy
fermion states identify Weyl-Kondo semimetals with
chiral or achiral Weyl nodes in the respective structural classes. We also develop the first search strategy of any kind for the difficult case of strongly correlated materials, which is also suitable for automation, using a combination of materials database,
symmetry classification and search for desired experimental properties, and propose as candidate topological heavy
fermion systems the
chiral CePt$_2$B and achiral Ce$_2$NiGe$_3$ and Ce$_6$Co$_{2-\delta}$Si$_3$. Our findings raise the prospect for strongly correlated metallic
topology in the unusual setting of exotic
quantum magnetism and, moreover, point a way to go beyond serendipity in the search for novel strongly correlated
quantum materials.
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All authors Kuan-Sen Lin, Yuan Fang, Henrique Fabrelli, Runhan Li, Andrey Prokofiev, Fang Xie, Jennifer Cano, Maia G. Vergniory, Silke Paschen, Qimiao Si
Materials Science
High-pressure single-crystal X-ray diffraction study of ErVO4
Josu Sanchez-Martin, Gaston Garbarino, Samuel Gallego-Parra et al. (+5 more)
We present an investigation into the
crystal structure of ErVO4 under variable pressure conditions. The high-pressure single
crystal X-ray diffraction experiments performed employing helium as the pressure medium facilitated structure refinements up to 24.1(2) GPa. The transition from zircon to scheelite was observed at a pressure of 7.9(1) GPa. In contrast to previous reports, we did not detect any sign of phase coexistence. We also did not observe the second phase transitions previously predicted by density-functional theory to occur below 20 GPa. The determination of the pressure dependence of unit-
cell parameters and volume yields precise values for linear compressibility of each axis and the pressure-volume equation of state for both the zircon and scheelite phases. Additional information on the mechanical properties of ErVO4, obtained from density-functional theory calculations, is also reported.
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All authors Josu Sanchez-Martin, Gaston Garbarino, Samuel Gallego-Parra, Alfonso Munoz, Sushree Sarita Sahoo, Kanchana Venkatakrishnan, Ganapathy Vaitheeswaran, Daniel Errandonea
Materials Science
High-Pressure X-Ray Diffraction Study of Scheelite-type Perrhenates
Neha Bura, Pablo Botella, Catalin Popescu et al. (+7 more)
The effects of pressure on the
crystal structure of scheelite-type perrhenates were studied using synchrotron powder X-ray diffraction and density-functional theory. At ambient conditions, the studied materials AgReO4, KReO4, and RbReO4, exhibit a tetragonal scheelite-type
crystal structure described by space group I41/a. Under compression, a transition from scheelite-to-M${\prime}$-fergusonite (space group P21/c) was observed at 1.6 and 7.4 GPa for RbReO4 and KReO4, respectively. The transition involves a relative volume decrease. On the other hand, AgReO4 underwent a phase transition to the M-fergusonite structure (space group I2/a) at 13.6 GPa. In this case there is no appreciable volume discontinuity. The room-temperature pressure-volume equation of state for the three studied perrhenates was estimated using a second-order Birch-Murnaghan equation of state. The results for the low-pressure phase are confirmed by density-functional theory calculations. The analysis of the bulk modulus shows that the compressibility of the compounds decreases following the sequence RbReO4 > KReO4 > AgReO4, which is related to the compressibility of the RbO8, KO8, and AgO8 bidisphenoid units. Density-functional theory also offers valuable insights into the elastic constants. Despite giving a good description for the low-pressure phase in the three compounds, density-functional theory cannot catch the structural phase transition observed in experiments. Reasons for it are discussed in the manuscript.
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All authors Neha Bura, Pablo Botella, Catalin Popescu, Frederico Alabarse, Ganapathy Vaitheeswaran, Alfonso Munoz, Brendan J. Kennedy, Jose Luis Rodrigo Ramon, Josu Sanchez-Martin, Daniel Errandonea
Soft Condensed Matter
Spatiotemporal Thermal Modulation and Patterning using a Programmable 1024 Element Microheater Array
Rahul Goyal, Jang-Hwan Han, Sadaf Pashapour et al. (+1 more)
Programmable microheater arrays are essential for a variety of applications including gas sensing, microfluidic lab on a chip devices, 3D printers, and biosensors that rely on DNA amplification. Increasing the density and number of heating elements directly correlates with the precision with which spatiotemporal heat profiles can be delivered. However, large arrays have thus far not been realized. One challenge is that as the number of elements in an array increases, the complexity of connecting them grows. Here, we show that row-column addressing provides a promising architecture for the efficient operation of a large micro-heater array. We introduce a programmable 32 x 32 microheater array consisting of individually addressable robust platinum (Pt)-based Joule heating elements- each smaller than 300 micrometer. We show that combining high-voltage multiplexed electronics and sequential addressing controlled by a high frequency clock, allows the independent operation of the 1024 microheater elements. We demonstrate the generation of heat images and the patterning of metallic structures formed from the
liquid metal Gallium. Our work demonstrates new capabilities for on-chip thermal devices, and opens the possibility to realize novel heat-controlled microactuation systems.
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All authors Rahul Goyal, Jang-Hwan Han, Sadaf Pashapour, Peer Fischer
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Loss Mechanisms in High-coherence Multimode Mechanical Resonators Coupled to Superconducting Circuits
Raquel Garcia Belles, Alexander Anferov, Lukas F. Deeg et al. (+14 more)
Circuit quantum acoustodynamics (cQAD) devices have a wide range of applications in
quantum science, all of which depend crucially on the
quantum coherence of the mechanical subsystem. In this context, high-overtone bulk acoustic-wave resonators (HBARs) are particularly promising, since they have shown very high quality factors with negligible dephasing. However, the introduction of piezoelectric films, which are necessary for coupling to a superconducting
circuit, can lead to additional loss channels, such as surface scattering and two-level systems (TLS). Here, we study the acoustic dissipation of HBAR resonators in cQAD systems and find that the defect density of the piezoelectric material and its interface with the bulk are limiting factors for the coherence. We measure acoustic modes with
phonon lifetimes up to 400 $\mu$s and lifetime-limited coherence times approaching one millisecond in the
quantum regime. When coupled to a superconducting
qubit, this leads to a hybrid system with a large
quantum coherence cooperativity of $C_{T_2}=1.1\times10^5$. These results represent a new milestone for the performance of cQAD devices and offer concrete paths forward for further improvements.
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All authors Raquel Garcia Belles, Alexander Anferov, Lukas F. Deeg, Loris Colicchio, Arianne Brooks, Tom Schatteburg, Maxwell Drimmer, Ines C. Rodrigues, Rodrigo Benevides, Marco Liffredo, Jyotish Patidar, Oleksandr Pshyk, Matteo Fadel, Luis Guillermo Villanueva, Sebastian Siol, Gerhard Kirchmair, Yiwen Chu
Strongly Correlated Electrons
Lowering the temperature of two-dimensional fermionic tensor networks with cluster expansions
Sander De Meyer, Atsushi Ueda, Yuchi He et al. (+2 more)
Representing the time-
evolution operator as a tensor network constitutes a key ingredient in several
algorithms for studying
quantum lattice systems at finite temperature or in a non-
equilibrium setting. For a
Hamiltonian composed of strictly short-ranged interactions, the Suzuki-Trotter decomposition is the main technique for obtaining such a representation. In [B.~Vanhecke, L.~Vanderstraeten and F.~Verstraete, Physical Review A, L020402 (2021)], an alternative strategy, the cluster expansion, was introduced. This approach naturally preserves internal and
lattice symmetries and can more easily be extended to higher-order representations or longer-ranged interactions. We extend the cluster expansion to two-dimensional fermionic systems, and employ it to construct projected entangled-pair operator (PEPO) approximations of Gibbs states. We also discuss and
benchmark different truncation schemes for multiplying layers of PEPOs together. Applying the resulting framework to a two-dimensional spinless
fermion model with attractive interactions, we resolve a clear phase boundary at finite temperature.
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All authors Sander De Meyer, Atsushi Ueda, Yuchi He, Nick Bultinck, Jutho Haegeman
Materials Science · Cross-listed from physics.comp-ph
Phase-Dependent Excitonic Light Harvesting and Photovoltaic Limits in Monolayer Y2TeO2 MOenes
Bill D. A. Huacarpuma, Jose A. dos S. Laranjeira, Nicolas F. Martins et al. (+5 more)
We investigate phase-dependent electronic and excitonic phenomena in monolayer Y2TeO2 MOenes in the 1T and 2H polymorphs using first-principles theory and an effective many-body framework.
Phonon spectra and elastic stability criteria establish both phases as dynamically and mechanically stable. Quasiparticle band structures reveal direct gaps in the near-infrared to visible range, with gap values increasing systematically from semilocal to hybrid exchange treatments. Optical spectra computed using a tight-binding Bethe-Salpeter approach demonstrate pronounced excitonic resonances arising from reduced dimensionality and weak dielectric screening. The
exciton binding energies reach 152 meV in the 1T phase and 126 meV in the 2H phase, reflecting enhanced
quantum confinement in the structurally denser phase. Our results identify Y2TeO2monolayers as a rare class of stable, direct-gap MOenes with strong excitonic effects, providing a platform for exploring many-body physics in low-dimensional oxychalcogenide systems especially for photovoltaic applications.
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All authors Bill D. A. Huacarpuma, Jose A. dos S. Laranjeira, Nicolas F. Martins, Julio R. Sambrano, Kleuton A. L. Lima, Santosh K. Tiwari, Alexandre C. Dias, Luiz A. Ribeiro Jr
Materials Science · Cross-listed from physics.optics
Purcell-enhanced Bright and Dark Exciton Emission from Perovskite Quantum Dots in Micro-ring Resonators
Lanyin Luo, Mohit Khurana, Ian M. Murray et al. (+5 more)
Colloidal
quantum dots (QDs) integrated with waveguide-coupled dielectric resonators are promising building blocks for compact on-chip light sources. However, deterministic placement of QDs with strong mode overlap at the desired location remains a challenge. Here, we demonstrate a simple and scalable strategy for integrating colloidal QDs with a waveguide-coupled Si3N4 micro-ring resonator platform and for controlling the radiative dynamics of both bright and dark
excitons via Purcell enhancement. We use strongly
quantum-confined CsPbBr3 QDs, which exhibit bright-
exciton emission at room-temperature, while emission at cryogenic temperatures originates from both bright and dark
excitons. The CsPbBr3 QDs are selectively retained on the Si3N4 micro-ring cavities through a
spin-coating/rinsing process, enabling efficient overlap with whispering-gallery modes and routing of the emission through integrated waveguides. We confirm accelerated decay of emission from both bright and dark
excitons for CsPbBr3 QDs coupled to the micro-ring cavities. These results demonstrate an effective route to integrate colloidal QDs with Si3N4 micro-ring cavities and to leverage cavity-enhanced emission in scalable integrated photonic devices.
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All authors Lanyin Luo, Mohit Khurana, Ian M. Murray, Sina Baghbani Kordmahale, Akanksha Pandey, Xiaohan Liu, Alexei V. Sokolov, Dong Hee Son
Strongly Correlated Electrons
Mott Intermittency at the Metal-Insulator Boundary
Yuxin Wang, Vladimir Dobrosavljević, Jan Jaroszyński et al. (+5 more)
The resistivity maximum at a temperature $T=T_{\mathrm{max}}$ is a recurring feature of bandwidth-tuned Mott systems, yet its meaning remains controversial: is it a coherence-incoherence crossover of an electronically homogeneous metal, or does it mark the onset of transport through a mixed landscape of metallic and insulating regions? Even more debated is whether a true phase-coexistence regime survives in the relevant parameter range, or whether apparent inhomogeneity is merely extrinsic. Here we address these questions by moving beyond temperature sweeps and probe charge transport in the time domain. Near $T=T_{\mathrm{max}}$, we find that the resistance of a model system, a quasi-two-dimensional Mott
spin liquid material, exhibits clear random-telegraph switching between discrete levels over long timescales. The statistics of the switching - sharp two-level behavior with thermally activated dwell times - point to a mesoscopic "current-controlling" region that dynamically toggles between metallic and insulating states, intermittently opening and closing the dominant conduction channel. This characteristic fluctuating dynamics provides direct evidence for intrinsic metal-
insulator coexistence and establishes $T\sim T_{\mathrm{max}}$ as the regime of Mott intermittency, where transport is governed by
stochastic domain switching rather than quasiparticle decoherence.
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All authors Yuxin Wang, Vladimir Dobrosavljević, Jan Jaroszyński, Yohei Saito, Atsushi Kawamoto, Andrej Pustogow, Martin Dressel, Dragana Popović
Materials Science · Cross-listed from physics.chem-ph
MBD-ML: Many-body dispersion from machine learning for molecules and materials
Evgeny Moerman, Adil Kabylda, Almaz Khabibrakhmanov et al. (+1 more)
Van der Waals (vdW) interactions are essential for describing molecules and materials, from drug design and catalysis to battery applications. These omnipresent interactions must also be accurately included in machine-learned force fields. The many-body dispersion (MBD) method stands out as one of the most accurate and transferable approaches to capture vdW interactions, requiring only atomic $C_6$ coefficients and polarizabilities as input. We present MBD-ML, a pretrained message passing neural network that predicts these atomic properties directly from atomic structures. Through seamless integration with libMBD, our method enables the immediate calculation of MBD-inclusive total energies, forces, and stress tensors. By eliminating the need for intermediate electronic structure calculations, MBD-ML offers a practical and streamlined tool that simplifies the incorporation of state-of-the-art vdW interactions into any electronic structure code, as well as empirical and machine-learned force fields.
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All authors Evgeny Moerman, Adil Kabylda, Almaz Khabibrakhmanov, Alexandre Tkatchenko
Soft Condensed Matter
Tire tread block dynamics
N. Miyashita and B. N. J. Persson
Temperature has a crucial influence on rubber friction and tire dynamics. The temperature field in a rubber tread block is the sum of the background temperature $T_0({\bf x},t)$, which varies slowly in time and space, and the flash temperature $\Delta T({\bf x},t)$, which in nonzero only close to the macroasperity contact regions, and which varies rapidly in time often on the millisecond time scale. Here we study the motion of a single tire tread block and how it is influenced by the flash temperature. We also present a theory and experimental results for the size of the macroasperity contact regions. In particular, we show that for a large enough nominal contact area, in most cases the diameter $D$ of the macroasperity contact regions are nearly independent of the elastic modulus and the nominal contact pressure.
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Disordered Systems and Neural Networks
Effect of glass stability on the low frequency vibrations of vapor deposited glasses
I. Festi, E. Alfinelli, D. Bessas et al. (+8 more)
Ultra-stable glasses prepared from the physical vapor deposition of organic molecules present a very low density of two-level states, the kind of glass defects that determine their peculiar low temperature thermal properties. Numerical simulations suggest that quasi-localized harmonic vibrational modes emerge in the soft regions associated with two-level states. However, the connection between the low frequency vibrational modes and the local structural instabilities of glasses remains unexplained. Here we exploit a recently developed spectrograph for
nuclear resonant analysis of inelastic X-ray scattering to probe the density of vibrational states of amorphous thin films of ultra-stable and conventional glasses down to an exceptionally low frequency of $\sim 70$ GHz. We show that the glass stability does not affect the harmonic vibrational modes at the lowest frequencies, despite a reduction of almost an order of magnitude in the density of two-level states. At the same time, the vibrational modes at higher frequencies, around the
boson peak maximum, are extremely sensitive to the glass stability. Although we cannot exclude the possible existence of quasi-localized modes in glasses, we show that their presence is not strictly necessary to describe the measured density of low frequency vibrations. The experimental developments here presented pave the way to the solution to the long-standing debate on the low frequency vibrations in glasses.
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All authors I. Festi, E. Alfinelli, D. Bessas, F. Caporaletti, A. I. Chumakov, M. Moratalla, M. A. Ramos, M. Rodríguez-López, C. Rodríguez-Tinoco, J. Rodríguez-Viejo, G. Baldi
Quantum Gases
Energy-resolved transport of ultracold atoms across the Anderson transition: theory and experiment
Jean-Philippe Banon, Sacha Barré, Ke Xie et al. (+7 more)
In a recent experiment [X. Yu et al., arXiv:2602.07654], energy-resolved measurements of an atomic matter wave spreading in a speckle potential enabled the direct observation of the three-dimensional Anderson transition. In this work, we present a quantitative theoretical description of the matter-wave dynamics based on a tailored implementation of the self-consistent theory of localization, which incorporates both the spectral and spatial properties of the state prepared in the disorder. We
benchmark this theoretical approach against ab initio numerical simulations, and use it to analyze the atom density profiles observed experimentally in the localized, diffusive, and critical regimes. Particular emphasis is placed on the key role of the atomic energy distribution, especially on the distinct contributions of Bose-condensed and thermal atoms to interpret the experimental profiles. Our framework provides a versatile and efficient theoretical toolbox for quantitatively describing wave-packet dynamics in three-dimensional disordered
quantum systems, which remain challenging for state-of-the-art large-scale numerical simulations.
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All authors Jean-Philippe Banon, Sacha Barré, Ke Xie, Hoa Mai Quach, Xudong Yu, Yukun Guo, Myneni Niranjan, Alain Aspect, Vincent Josse, Nicolas Cherroret
Soft Condensed Matter
Micellar effects on Ostwald ripening in emulsions: Transition from cubic to quadratic particle size growth
Alexey Kabalnov
Ostwald ripening in O/W emulsions in presence of solubilizing micelles is theoretically studied. At small average sizes, the kinetics is predicted to follow the classical Lifshits-Slezov-Wagner cubic law, with the rate proportional to the molecular solubility of the oil in water, as if no micelles were present. At larger particle sizes the kinetics transitions to the Wagner's quadratic law. The crossover point for the kinetics depends on the dynamics of the oil solubilizate-micelle exchange; it is set by the value of the oil atmosphere distribution parameter, kappa, which, somewhat like Debye length, is proportional to the square root of the micellar concentration. It should be noted that in the range when 1/kappa is close to the particle average radius, the ripening kinetics still nearly follows the cubic law, with only moderate deviations; in this case, the micellar effects are experimentally seen not as the deviations from the linearity, but as an apparent increase in the cubic rate. The increase is predicted to be larger in case of nonionic micelles of ethylene
oxide type compared to ionic ones.
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Soft Condensed Matter
Hydrodynamics of Dense Active Fluids: Turbulence-Like States and the Role of Advected Activity
Sandip Sahoo, Siddhartha Mukherjee and Samriddhi Sankar Ray
Dense suspensions of self-propelled bacteria and related active fluids exhibit spontaneous flow generation,
vortex formation, and spatiotemporally chaotic dynamics despite operating at vanishingly small Reynolds numbers. These phenomena, commonly referred to as active
turbulence, display striking visual and statistical similarities to classical inertial
turbulence while arising from fundamentally different nonequilibrium mechanisms. In this article, we present a combined review and theoretical study of hydrodynamic models for dense active fluids, with particular emphasis on bacterial suspensions described by the Toner–Tu–Swift–Hohenberg (TTSH) framework. We review key experimental and theoretical developments underlying the analogy between active and inertial
turbulence, highlighting the emergence of multiple dynamical regimes and the conditions under which universal spectral and intermittent behavior arises in homogeneous systems. Moving beyond the conventional assumption of spatially uniform activity, we introduce a minimal model in which the activity field is heterogeneous and dynamically advected by the flow it generates. Thus treating activity as a spatiotemporally evolving field coupled to the TTSH dynamics, we investigate how advection and
diffusion lead to sharp activity fronts, confinement of turbulent motion, and complex interfacial morphologies. Our numerical results demonstrate that spatial variations in activity can induce transient coexistence of distinct spectral regimes and that universality in active
turbulence is inherently local and time-dependent in heterogeneous systems. These findings underscore the importance of treating activity as a dynamical field in its own right and provide a framework for studying active
turbulence in more realistic, spatially structured biological and synthetic active matter systems.
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Materials Science
Discovering new photovoltaics using optimal transport theory
Matthew A. H. Walker, Zibo Zhou, Junayd Ul Islam et al. (+1 more)
Searching by chemical and structural analogy is one of the most commonly used and successful approaches to materials discovery. However, formulating this task for algorithmic implementation raises the question of how we define similar materials. Methods have been proposed for searching materials space using vectors based on chemical composition and functional fragments in the material. Descriptors for structural similarity have also been proposed. However, the question of how to incorporate and balance structural and compositional similarity measures in a single metric remains open. Here, we adapt methods developed for calculating distances between undirected graphs and apply them to crystalline materials similarity. The Fused Gromov-Wasserstein (FGW) metric uses optimal transport theory to map between two graphs considering a balance of the graph structure and the information present at the nodes of the graph (atoms in
crystals). We apply the method to exploring new photovoltaic materials. We demonstrate that FGW is competitive with
embeddings from an equivariant graph neural network, trained on $> 10^6$ materials, despite minimal training. We then apply FGW to a discovery campaign to identify materials from the Materials Project database that have not previously been explored as photovoltaics, but have similarities to known high-efficiency materials. After validating predictions with hybrid density functional theory, we identify seven previously unexplored high-efficiency photovoltaic absorber candidates, including Cs$_5$Sb$_8$, which is found to have a predicted SLME of $> 30\%$ and to be thermodynamically stable. The FGW approach demonstrates the power of strong inductive biases for developing metrics for materials exploration with minimal training data.
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All authors Matthew A. H. Walker, Zibo Zhou, Junayd Ul Islam, Keith T. Butler
Statistical Mechanics
XY Model with Persistent Noise
Xia-qing Shi, Hugues Chaté and Benoît Mahault
We consider a 2D XY model subjected to time-correlated noise, a model of direct relevance to active
crystals, which were shown recently to be able to support very large deformations without melting in the presence of persistent fluctuations. We find that our persistent XY model can remain quasi-ordered in spite of correlations decaying much faster than allowed in
equilibrium. We then investigate theoretically and numerically the order-disorder transition and conclude that it remains of the Berezinskii-Kosterlitz-Thouless type, but with scaling exponents that vary with the persistence time of the noise.
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Strongly Correlated Electrons · Cross-listed from hep-th
Nonequilibrium steady states in driven holographic Weyl semi-metals
Matteo Baggioli, Sebastian Grieninger and James Stokes
Three-dimensional Weyl materials provide a controlled setting for exploring Floquet dynamics in open
quantum systems, including nonequilibrium steady states (NESS). Motivated by the desire for a strongly-coupled description, we employ holography to analyze the formation and stability of a NESS in a Weyl semi-metal induced by an external circularly polarized electric field. A time-periodic steady-state solution is constructed and its stability is determined from the spectrum of out-of-
equilibrium quasinormal modes (Floquet exponents). A stable region in the drive parameter space is identified; beyond a critical curve, the Floquet exponents enter the upper half of the complex plane, leading to a superharmonic response. At sufficiently strong driving, chaotic time
evolution emerges in the fully nonlinear initial-boundary value problem. The anomaly-induced response of the NESS to an external
magnetic field is also computed, and the resulting behavior is related to the previously proposed
chiral pumping effect.
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Quantum Gases
Universal Transport Properties of Continuous Quantum Gases
Zi-yang Liu, Xiangguo Yin, Yunbo Zhang et al. (+2 more)
The Drude weight characterizes ballistic transport in
quantum many-body systems. Although analytical calculations of Drude weights have been extensively studied in integrable models, their direct connections to finite-temperature macroscopic state functions remain unestablished, especially for continuous multicomponent
quantum gases. In the present work, we use generalized hydrodynamics and the thermodynamic Bethe ansätz to calculate exactly the Drude weights for one-dimensional continuous integrable systems, including the Lieb-Liniger and Bose-
Fermi mixture models. We derive universal exact relations between Drude weight
matrix components and key thermodynamic densities (particle density, enthalpy,
entropy). Analytic expressions for Drude weight are obtained across different physical regimes, i.e. strong- and weak-coupling regimes in addition to universal scaling laws near the
quantum phase transitions. To bridge theory and experiment, we simulate two experimental protocols, linear potential quench and bipartitioning quench, to enable reliable measurements of the Drude weights. Using these protocols, we calculate the charge and energy Drude weight for Lieb-Liniger gas and compare with recent measurements reported in [Science 391, 290 (2026)], showing excellent agreement with particle density and enthalpy, respectively, thus offering deeper physical insights into experimental observations. Our findings directly link ballistic transport properties to thermodynamics, providing rigorous theoretical
benchmarks for future ultracold atomic gas experiments.
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All authors Zi-yang Liu, Xiangguo Yin, Yunbo Zhang, Shizhong Zhang, Xi-Wen Guan
Strongly Correlated Electrons
Crystallography-driven molecularization of a two-dimensional spin-$3/2$ magnet
Hari Borutta, Tobias Müller, Ronny Thomale et al. (+2 more)
Large-
spin two-dimensional magnets are generally expected to develop conventional long-range order once the dominant exchange scale becomes appreciable. The layered
spin-$3/2$ maple-leaf compound Na$_2$Mn$_3$O$_7$ defies this expectation: despite sizable
antiferromagnetic interactions and no evident disorder, it exhibits no
magnetic ordering and displays two well-separated thermodynamic crossover scales. We show that this behavior originates from a crystallography-driven molecularization of the
magnetic degrees of freedom. The low-
symmetry structure partitions the Mn sublattice into inequivalent exchange pathways, generating a pronounced hierarchy that nearly isolates
antiferromagnetic hexagons.
Magnetic correlations therefore develop in two stages: first within individual hexagons at a scale set by the dominant exchange, and only at much lower temperatures do frustrated inter-hexagon couplings attempt to establish coherence across the
lattice. While isolated hexagons reproduce the two-step thermodynamic structure, the experimentally relevant temperature scales emerge only once the hexagons are embedded in the frustrated two-dimensional network. The resulting
quantum ground state is magnetically disordered, characterized by strong intra-hexagon correlations and rapidly decaying inter-hexagon correlations. These results identify crystallographic inequivalence as a materials-level mechanism for stabilizing molecularized and
quantum-disordered states even in large-
spin two-dimensional magnets.
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All authors Hari Borutta, Tobias Müller, Ronny Thomale, Harald O. Jeschke, Yasir Iqbal