Soft Condensed Matter
The structural relaxation time of a polymer glass during deformation
Pradip K. Bera, Grigori A. Medvedev, James M. Caruthers et al. (+1 more)
In order to determine the structural relaxation time of a
polymer glass during deformation, a strain rate switching experiment is performed in the steady-state plastic flow regime. A lightly cross-linked poly (methyl methacrylate) (PMMA) glass was utilized, and simultaneously the segmental motion in the glass was quantified using an optical probe reorientation method. After the strain rate switch, a non-monotonic stress response is observed, consistent with previous work. The correlation time for segmental motion, in contrast, monotonically evolves towards a new steady-state, providing an unambiguous measurement of the structural relaxation time during deformation, which is found to be approximately equal to the segmental correlation time. The Chen-Schweizer model qualitatively predicts the changes in the segmental correlation time and the observed non-monotonic stress response. In addition, our experiments are reasonably consistent with the material time assumption used in
polymer deformation modeling; in this approach, the response of a
polymer glass to a large deformation is described by combining a linear-response model with a time-dependent segmental correlation time.
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All authors Pradip K. Bera, Grigori A. Medvedev, James M. Caruthers, Mark D. Ediger
Statistical Mechanics · Cross-listed from quant-ph
Exact quantum circuits for a lattice Boltzmann realization of the Dirac equation
Nilesh Sawant, Ethan Young, Kevin Patrick Griffin et al. (+1 more)
The
quantum lattice Boltzmann scheme of Succi and Dellar advances a four-component Dirac spinor on a
lattice by a fixed sequence of local, exactly norm-preserving operations: a basis rotation, a collision, a streaming shift, and the inverse rotation. While this correspondence has been noted qualitatively, it has remained unclear whether it can be realized exactly and unitarily as a gate-model
quantum circuit. This unitarity is a structural property of the scheme, which should, in principle, enable an operator-by-operator port onto
quantum hardware. We give a gate-level construction of every operation of the three-dimensional Dirac QLB scheme: the fixed rotation gates, the collision gate, the streaming shift as a controlled increment on a position register, the position-dependent potential as a phase oracle, and periodic and reflecting boundary conditions as
unitary circuits. Together, these constructions provide the first complete demonstration that the scheme is exactly representable in the gate model without any approximation beyond the classical method itself. We then compose them into single-axis, two- and three-dimensional time steps. On a state-vector emulator the resulting
circuits reproduce the classical QLB solver to machine precision, thus verifying our
quantum implementation. Our aim is representability and correctness rather than computational speedup; questions of state preparation, asymptotic cost, and hardware noise are identified as open avenues for future work. Appendices restore physical units, derive the scheme's Zitterbewegung in closed form and compare it with a trapped-ion simulation, and execute a reduced two-site instance on a Rigetti superconducting processor, where choosing the
qubits from the live calibration lowers the state-preparation error. All operators,
circuits, and figures are reproducible from the open-source quantumKineticMethods library.
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All authors Nilesh Sawant, Ethan Young, Kevin Patrick Griffin, Michael Martin
Mesoscale and Nanoscale Physics
Observation of metastable chiral domain walls in a topological magnet
Richen Xiong, Chenxin Qin, Zhaoyu Han et al. (+17 more)
The interplay between
topology and correlation can give rise to exotic collective excitations. The integer and fractional
quantum anomalous
Hall (QAH) magnets recently discovered in two-dimensional (2D) flatband systems are predicted to host
spin excitations distinct from those in conventional magnets. Experimentally, nevertheless, these new excitations remain largely unexplored. Here we investigate
spin-valley excitations in a twisted MoTe2 moiré superlattice using resonant ultrafast pump-probe spectroscopy. We observe a metastable
spin-valley excitation in the QAH magnet below T ~ 3.7 K that survives reverse
magnetic field several times larger than the saturation field. The behavior of this excitation is sharply distinct from ordinary domain walls and
magnons, indicating a new type of
spin-valley textures unique to topological magnets. We propose that these textures are
chiral domain walls with an in-plane winding of the pseudospin order parameter along the domain wall. Their metastability arises from the interplay between the topological winding in real space and the
quantum geometry of the parent bands in momentum space through a universal mechanism. These
chiral domain walls govern the nonequilibrium dynamics of QAH magnets and may play a central role in their stability. Our study highlights intrinsic
quantum geometry effects on
spin excitations in topological magnets; and provides key insights into the fundamental mechanism limiting stability of topological protection.
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All authors Richen Xiong, Chenxin Qin, Zhaoyu Han, Nisarg Chadha, Qiang Gao, William Holtzmann, Weijie Li, Jiaqi Cai, Yi Guo, Weihanzhang Guo, Qi Chen, Samuel L. Brantly, Sam Bonkowsky, Chen Huang, Kenji Watanabe, Takashi Taniguchi, Andrea F. Young, Xiaodong Xu, Eslam Khalaf, Chenhao Jin
Materials Science
Nonreciprocity reversal of magnetoacoustic attenuation in NiFe alloy thin films
Mingran Xu, Kei Yamamoto, Kouta Kondou et al. (+8 more)
Nonreciprocity, the asymmetry of transport, underlies technologies from the diode to the microwave isolator. In a ferromagnet, a surface acoustic wave generates an elliptical effective field with propagation-locked handedness, breaking the reciprocity of its propagation. Despite decades of study on this phenomenon, a method for controlling the sign of the nonreciprocity has remained elusive. Here we observe a sign reversal in Ni$_x$Fe$_{100-x}$ films. A 0.8 at.% change across Permalloy's zero-magnetostriction composition, where the magnetoelastic coefficient $b$ changes sign, reverses the handedness of the elliptical effective field and thereby the nonreciprocity, from 78.6% to -61.8%. Angle-dependent measurements and
spin-wave-ellipticity modelling show that reversing the sign of $b$ reverses the handedness of the elliptically polarized effective field. Aided by cubic frequency scaling, we resolve the sign of $b$ down to -0.05 MPa in a 10-nm film, establishing nonreciprocity as a nanoscale probe of magnetoelastic coupling.
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All authors Mingran Xu, Kei Yamamoto, Kouta Kondou, Zheng Zhu, Liyang Liao, Kiyohiro Adachi, Tomoka Kikitsu, Daisuke Hashizume, Dirk Grundler, Sadamichi Maekawa, Yoshichika Otani
Mesoscale and Nanoscale Physics
Temperature-tunable spin-wave refraction using superconducting control elements
Pim H. Vree, Merel A. Bouma, Michael Borst et al. (+3 more)
Spin waves are promising signal carriers for microwave control at the micrometer scale. However, realizing low-damping, tunable control of
spin-wave propagation remains a central challenge. Here we use
magnetic shielding by superconducting control elements to tune the local
spin-wave dispersion and realize temperature-controlled refraction of
spin waves in a thin-film
magnetic insulator. Using
magnetic imaging based on
spins in diamond, we characterize the refractive index and demonstrate both positive and negative refraction as well as wavefront shaping by the
superconductors. The observed refraction is explained by a geometrical analysis of the superconductivity-induced modification of the
hyperbolic spin-wave dispersion. Our results demonstrate that
superconductors enable tunable
spin-wave optical elements, opening new opportunities for microwave control in classical or
quantum information devices.
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All authors Pim H. Vree, Merel A. Bouma, Michael Borst, Tomas T. Osterholt, Rembert A. Duine, Toeno van der Sar
Superconductivity
Emergence of Bogoliubov Fermi Surfaces in hybrid Al/InAs heterostructures
S. Feyrer, V. Dimic, I. Lobato et al. (+15 more)
We investigate the microwave electrodynamics of a proximitized two-dimensional electron gas in hybrid
superconductor/
semiconductor heterostructures. Using lumped-element resonators with inductor wires oriented relative to an in-plane
magnetic field, we directly probe the superfluid stiffness via the kinetic inductance. As the field increases, the resonance frequency exhibits a non-monotonic and strongly anisotropic
evolution that cannot be explained by orbital pair breaking alone. We show that this behavior is consistent with the emergence of Bogoliubov
Fermi surfaces, which selectively suppress the supercurrent response depending on the direction of the
magnetic field. Microscopic calculations of the stiffness tensor capture the observed anisotropy driven by the interplay of Zeeman and orbital Fulde-Ferrell effects. Our results establish microwave stiffness measurements as a sensitive probe of anisotropic gapless superconductivity in hybrid systems.
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All authors S. Feyrer, V. Dimic, I. Lobato, A. Kirchner, P. Drexler, L. Rupp, D. Bougeard, T. Lindemann, S. Gronin, G. Gardner, M. J. Manfra, G. F. R. Ruiz, C. A. Balseiro, L. Arrachea, M. Aprili, N. Paradiso, C. Strunk, L. Tosi
Mesoscale and Nanoscale Physics
Anderson Orthogonality as Measurement Backaction in Coupled Quantum Dots
Will Grant, Sarath Sankar, Elena Cornick et al. (+9 more)
Measurement perturbs a
quantum system by coupling it to external degrees of freedom, but detector backaction depends on the physical mechanism of measurement itself. In solid-state devices, detectors driven far from
equilibrium to enable faster measurements produce backaction that can often be understood as classical noise. However, a strong measurement can also induce backaction from
quantum many-body correlations in the detector that are intrinsic to the measurement, even without shot noise. Here, we probe this near-
equilibrium backaction through the effect of a
quantum-dot charge sensor on tunnelling between a second
quantum dot and its reservoirs. The measurement realizes the Anderson Orthogonality Catastrophe (AOC): electrons in the detector leads reorganize in response to an abrupt change in local scattering potential, suppressing resonant tunnelling while enabling inelastic processes that exchange energy with the detector. Changing the detector energy level tunes the AOC backaction from negligible to dominant in the tunnelling dynamics. More broadly, these results establish detector-induced many-body correlations as a controllable influence on
quantum dynamics.
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All authors Will Grant, Sarath Sankar, Elena Cornick, Vahid Movahed, Johann Drayne, Silvia Lüscher, Saeed Fallahi, Geoffrey C. Gardner, Michael J. Manfra, Eran Sela, Yigal Meir, Joshua Folk
Strongly Correlated Electrons
Excitonic Magnetism in Ruthenium Pyrochlores
Swetlana Swarup, Yang Yang and Natalia B. Perkins
Strong
spin-orbit coupling in $d^4$ systems is expected to stabilize a nonmagnetic $J=0$ singlet ground state, yet many ruthenium pyrochlores exhibit robust long-range
magnetic order. Motivated by this apparent contradiction, we develop a microscopic theory of Van Vleck excitonic magnetism on the pyrochlore
lattice. Starting from a multi-orbital Hubbard model with
spin-orbit coupling, we derive the effective superexchange interactions within the low-energy singlet–triplet
manifold of Ru$^{4+}$ ions. We analyze the resulting excitonic
Hamiltonian using both the spectrum of triplon excitations and a variational treatment of the condensed phase. We identify the instability of the nonmagnetic singlet state toward triplon condensation and determine the resulting
magnetic phase diagram as a function of the microscopic hopping parameters. The phase diagram reproduces the
magnetic orders known from conventional pyrochlore models while also predicting an additional
magnetic phase unique to the singlet–triplet description. Finally, we apply the theory to the pyrochlore ruthenates, with particular emphasis on Nd$_2$Ru$_2$O$_7$, and show that it lies in close proximity to the excitonic
quantum critical point. Our results establish a microscopic framework for understanding excitonic magnetism in pyrochlore ruthenates and their
magnetic excitation spectrum, providing direct connections to spectroscopic probes, including Raman scattering.
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Disordered Systems and Neural Networks · Cross-listed from math.PR
Free energy of Ising models under a spectral condition
Andrea Montanari and Michael Ren
A sequence of sparse weighted graphs $(G_N:N\ge 1)$ indexed by the number of vertices $N$ is said to be left-convergent if all (suitably weighted) subgraph counts converge to a limit as $N\to\infty$. This notion generalizes in a natural way Benjamini-Schramm's definition of local weak convergence. A broad research agenda aims at determining which `global' graph properties are determined by left or local weak convergence (in other words, which of these properties are in fact local). We prove that, under a spectral condition on the weighted adjacency
matrix ${\boldsymbol A}_N$ of graph $G_N$, the free energy density of the Ising model on this weighted graph is continuous in the left convergence
topology (and hence is a local function). Our proof uses the decomposition of the Ising measure as a log-concave combination of product measures, and of the rapid mixing of Langevin dynamics for log-concave measures. As applications, we derive new limit
theorems for the free energy density of
spin glasses, antiferromagnets, and magnetization constrained
ferromagnetic models, on locally tree-like graphs.
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Mesoscale and Nanoscale Physics
Effectiveness of Some 0 dB Cryogenic Microwave Attenuators as Thermal Heatsinks
J.T. Klomp, Haoyun Huang and G.A. Csathy
Coaxial cables are widely used in radiofrequency and microwave cryogenic setups for condensed matter and
quantum experiments. Since the inner conductor of coaxes is often in good thermal contact with the sample to be measured, it is desirable to know the phononic heat channeled by the inner conductor. Although cryogenic attenuators are widely used to thermalize the inner conductor of coaxes, to our knowledge, quantitative information is not available. We present data on the effectiveness of three commercially available 0 dB attenuators as thermal heatsinks. In particular, we measured the temperature of the inner pin of several 0 dB attenuators under a heat load. This information will aid in designing and carefully controlling the thermal environment of samples in high-frequency experiments mounted in dilution refrigerators and on
nuclear demagnetization stages.
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Mesoscale and Nanoscale Physics
Theory of spin-wave transport in ferromagnet-superconductor heterostructures: Negative refraction, perfect imaging and temperature-controlled spin-wave optics
Tomas T. Osterholt, Thijs van der Meer, Pim H. Vree et al. (+4 more)
We investigate
spin-wave transport in
ferromagnetic insulator-
superconductor (FMI-SC)
heterostructures and develop a general theoretical framework for
spin-wave optics in these hybrid systems. We demonstrate that Meissner screening by the
superconductor gives rise to a range of unconventional wave phenomena, including negative phase- and group-velocity refraction, and reflection and refraction laws that differ fundamentally from their optical counterparts. Within this framework, we derive the
spin-wave Fresnel equations governing reflection and transmission at FMI-SC interfaces and show that the scattering properties exhibit a pronounced temperature dependence, enabling tunable
spin-wave mirrors and refractive elements. Most strikingly, we find that superconducting screening can produce nearly straight isofrequency contours, far flatter than the kinked, intrinsically curved contours attainable in conventional dipolar
spin-wave systems. We show that these straight contours enable functionalities such as perfect
spin-wave imaging, efficient waveguiding, and interferometric elements, such as phase shifters and beam splitters, with unconventional properties. Our results establish FMI-SC
heterostructures as a versatile platform for temperature-tunable
spin-wave optics and interferometric magnonic devices.
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All authors Tomas T. Osterholt, Thijs van der Meer, Pim H. Vree, Merel A. Bouma, Michael Borst, Toeno van der Sar, Rembert A. Duine
Disordered Systems and Neural Networks · Cross-listed from quant-ph
KPZ Superdiffusion of Local Correlators in Diffusive Random Quantum Circuits
Ewan McCulloch
We study the single-particle Green's function $G(x,t)=\langle \sigma^-_x(0)\sigma^+_0(t)\rangle$ in one-dimensional particle-number-conserving random
unitary circuits coupled to an external bath. For fixed spacetime disorder, we argue that $G(x,t)$ is governed, in both the strong- and weak-noise limits, by directed waves in a random medium. We find Kardar-Parisi-Zhang (KPZ) scaling in the wandering statistics of the normalized spatial distribution $p(x,t)\propto |G(x,t)|^2$ and in the associated free energy. In particular, its center $\langle x(t)\rangle\equiv\sum_x x\, p(x,t)$ wanders on a length-scale $\mathcal{O}(t^{2/3})$, while sample-to-sample fluctuations of $-\log\sum_x |G(x,t)|^2$ scale as $t^{1/3}$. At weak noise $\gamma \ll 1$, the crossover to the strong-disorder fixed point occurs at a parametrically long time $\mathcal{O}(\gamma^{-3/2})$. These predictions are confirmed numerically using tensor-network simulations of the noisy operator dynamics in individual
circuits at moderate noise, and of a phase-annealed proxy retaining hopping disorder at weak noise.
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Materials Science
Sublattice-resolved coherent phonon dynamics in charge density waves
Kyoung Hun Oh, Honglie Ning, Zongqi Shen et al. (+15 more)
Phonons govern fundamental material properties and play a central role in various electronic phase transitions. Coherent driving of specific
phonon modes enables on-demand phase control, motivating sublattice-resolved identification of real-space
phonon motions. Yet experimentally resolving these motions remains challenging, limiting precise
phonon-based control. Here, we introduce a dynamical protocol to track element-resolved
phonon dynamics in the charge density wave material EuTe4, in which the dominant Te-sublattice charge order is accompanied by a previously unreported Eu-sublattice component. We leverage the elemental selectivity of time-resolved resonant X-ray scattering to reveal three coherent
phonon modes with distinct sublattice character, thereby disentangling Eu- and Te-dominated
lattice dynamics, in good agreement with theoretical calculations of the
phonon eigenvectors. This time-domain approach, which surpasses the energy-resolution limits of conventional frequency-domain inelastic scattering, provides a broadly applicable framework for decomposing coherent
phonons in multi-element materials, which is crucial for the targeted control of phases of matter.
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All authors Kyoung Hun Oh, Honglie Ning, Zongqi Shen, Yifan Su, Jack Maier, Gyeongbo Kang, Hyeongi Choi, Dong Wu, Qiaomei Liu, Hyun-Woo J. Kim, Seunghyeok Ha, Jaehwon Kim, Byungjune Lee, B. J. Kim, N. L. Wang, Yao Wang, Hoyoung Jang, Nuh Gedik
Strongly Correlated Electrons
Composite Fields and Tree Expansions: A Unified Framework for Renormalized Vertex Decompositions
Oleksandr Sulyma and Benedikt Schneider
One-particle irreducible vertices encode renormalized interactions in
quantum field theories, but their practical treatment remains challenging due to their high dimensionality and nontrivial dependence on external variables such as momenta or frequencies. We develop a functional framework that algebraically reorganizes the diagrammatic content of the vertex functions into more efficient building blocks and reveals several established vertex decompositions, such as parquet, single-
boson exchange, asymptotic classes and symmetric
estimators, as different realizations of a common functional structure. Based on Legendre transforms of the effective action of composite fields, the formalism shows that different vertex representations arise from different choices of composite degrees of freedom. We demonstrate that in our framework higher-order vertices can be systematically obtained via tree expansions, thereby extending the aforementioned decompositions beyond the four-point level. Because our findings are independent of any specific physical setting, the framework applies broadly to
quantum field theories in condensed matter physics, particle physics, and beyond.
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Statistical Mechanics
A Universal Control Budget for First-Passage Kinetics
Shiling Liang and Ruicheng Bao
The first-passage time is the natural observable of reaction completion, yet how its mean responds to a rate change has lacked a general constraint. We show that the logarithmic sensitivity of the mean first-passage time of any finite Markov chain to any rate is bounded by one in magnitude, and that these sensitivities sum to -1. Together the two laws form a conserved control budget: speeding completion through some transitions must be paid for by others, and a coordinated change shifts the completion time only as far as the budget allows. Raising an activation barrier or shifting the depth of a well moves many rates at once, yet neither can shift the completion time further than a single rate could. The budget caps kinetic-proofreading discrimination at the checkpoint count, and prices it in sensitivity to substrate concentration.
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Strongly Correlated Electrons
Phonon spectral functions of low-density polaron metals
Luis Walther, Alberto Nocera and Mona Berciu
We use the density
matrix renormalization group (DMRG) to compute the
phonon spectral function of a one-dimensional spinless Holstein model doped with a low but finite carrier concentration, $x \leq 0.15$, as a function of the electron-
phonon coupling $\lambda$. To the best of our knowledge, these are the first such results in this regime, complementing extensive prior work at the single-polaron level ($x\to 0$). We find that significant
phonon spectral weight is transferred both below, all the way down to $\omega=0$, and above the bare
phonon energy $\Omega$, in stark contrast with the Kohn-anomaly phenomenology expected in the Migdal limit, where weight remains centered near $\Omega$ with a kink at $q=2k_F$. No signature of this $2k_F$ kink appears in our results. This behavior is captured qualitatively by the Random Phase Approximation (RPA), and semi-quantitatively, at negligible extra computational cost, by a “dressed RPA” scheme in which the electron addition propagator is renormalized using the Momentum Average (MA) approximation for the low-density electron-polaron. By contrast, adding the lowest-order vertex correction to this dressed scheme produces unphysical negative spectral weight, signaling that vertex and propagator dressings must be treated consistently once the propagators are dressed nonperturbatively. Our results provide an efficient approximation for the
phonon spectral functions of low-density polaron metals, a regime relevant to weakly doped
insulators.
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Mesoscale and Nanoscale Physics
Vector Edge Solitons and Domain Walls in a Nonlinear Mechanical Topological Insulator
David D. J. M. Snee and Yi-Ping Ma
We report nonlinear edge waves in a 2D mechanical topological
insulator. A bulk
lattice consists of pendulums with on-site cubic nonlinearity connected by linear springs realizing
quantum spin Hall effect. We show that the nonlinear interaction between two edge modes with equal group velocities (EGV) is described by a 1D two-component coupled nonlinear Schrödinger (CNLS) equation. On the interface separating two bulk
lattices with opposite
spin Chern numbers, we construct linear springs such that the dispersion relation exhibits EGV points with favorable CNLS coefficients. Thus, we realize nonlinear edge waves propagating along the interface, including bright-bright (BB) edge
solitons for focusing CNLS coefficients, and dark-dark edge
solitons, edge domain walls, and dark-bright edge
solitons for defocusing CNLS coefficients. In terms of the site amplitudes, these solutions resemble bright and dark breathers. These solutions should be topologically protected when both carrier frequencies lie within a band gap, which we explicitly show by passing BB edge
solitons through compact defects on the interface. We also show energy transfer in BB edge
soliton collisions with potential application to collision-based computing. Generally, vector edge
solitons exhibit a large parameter space for
soliton collisions, which endows mechanical devices with greater potential for information processing and other functionalities.
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Mesoscale and Nanoscale Physics
Multi-State Geometry of Density Matrices and Rectification Sum Rules
Barry Bradlyn
The geometry of
quantum states has emerged as a key ingredient in understanding the linear and nonlinear responses of
quantum materials. To date, however, the connection between geometry and nonlinear response is best understood for clean, noninteracting systems at zero temperature. In this work, we develop a theory of multi-state geometry for density
matrices and use it to derive sum rules for second-order rectification, making no assumptions about the strength of disorder or interactions. We first show that perturbation theory for thermal density
matrices gives rise to two dual information-theoretic connections and an almost complex structure. We introduce a complex,
quantum generalization of the Amari-Chentsov tensor of classical information theory, the cQAC tensor, which captures the multi-state geometry of the perturbed density
matrix. We derive a zero-temperature sum rule for the frequency-integrated DC rectification response of an
insulator as a difference between a ground state third cumulant and the complex distortion tensor, a multi-state
geometric quantity built from the cQAC tensor. This generalizes known single-particle sum rules for the shift and nonlinear
Hall currents to many-body systems and general perturbations. Specializing to the shift current, we resolve the
geometric contribution for multiband
insulators into particle-like and hole-like terms. We verify the sum rule numerically in a generalized Kane-Mele model, finding that the
geometric contribution can dominate the integrated response. Finally, we show that although the splitting of the sum rule into cumulant and
geometric contributions does not survive at nonzero temperature, the measured sum rule for
insulators differs from its zero-temperature form by corrections exponentially small in the gap, allowing low-temperature rectification measurements to probe the multi-state geometry of
insulators.
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Materials Science
Metal-Coordination Effects on the Stability and ORR/OER Activity of Layered Organometallic Single-Atom Catalysts: A Theoretical Study
Pedro H. Souza, Victor Hoyos-Sinchi and Walter Orellana
Organometallic layered materials have emerged as promising single-atom catalysts for oxygen reduction and
evolution reactions, but their practical use has been limited by insufficient electrochemical stability. Here, we present a density functional theory study clarifying the relationship between catalytic activity and stability in organometallic single-atom catalysts with metal-N$_4$ (MN$_4$) and metal-O$_4$ (MO$_4$) coordination. We compare
graphene-embedded MN$_4$ motif and phthalocyanine-like frameworks with MO$_4$-coordination frameworks, including M$_4$(OHPTP)$_2$ and M$_3$(HHTP)$_2$ (M = Mn, Fe, Co, Ni, Cu, Zn). Stability is assessed by surface Pourbaix analysis, while activity is evaluated using the computational hydrogen electrode method. MN$_4$ systems show competitive overpotentials but suffer strong pH-dependent instability. In contrast, MO$_4$ frameworks exhibit enhanced robustness across wide pH ranges while maintaining good catalytic performance. A proposed stability descriptor enables direct comparison across systems, identifying MO$_4$ coordination structures, particularly M$_4$(OHPTP)$_2$ (M = Zn, Co) as optimal for balancing activity and stability in practical electrocatalysis.
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Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Impact of Nonlinearities on Local Kinetic and Thermokinetic Uncertainty Relations in Bosonic Transport
Didrik Palmqvist, Luca Magazzù, Milena Grifoni et al. (+1 more)
The precision of transport observables can be bounded by the
entropy production and the activity of the transport process via kinetic and thermokinetic uncertainty relations. In linear bosonic systems, such uncertainty relations can provide tight bounds when the activity is replaced by a local activity of the measurement contact of interest—even in the strong-coupling regime. How much nonlinearities (or interactions) impact the validity and predictiveness of these local bounds and how much this impact depends on the concrete definition of activity are open questions that we address for two experimentally relevant model systems, a harmonic oscillator network and the intrinsically nonlinear
spin-
boson model. We thereby provide experimentally testable predictions on how nonlinearities impact or even break local kinetic and thermokinetic precision bounds.
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All authors Didrik Palmqvist, Luca Magazzù, Milena Grifoni, Janine Splettstoesser
Strongly Correlated Electrons · Cross-listed from quant-ph
Approximate Quantum Error Correction at Chiral Topological Edges
Yuntai Song, Zejun Liu, Zhencheng Wang et al. (+2 more)
Topologically ordered phases naturally realize
quantum error correction through nonlocal encoding of
quantum information. More recently, conformal field theories have been shown to realize approximate
quantum error-correcting codes, but such constructions generally require fine tuning to criticality. Here we introduce a family of approximate
quantum error-correcting codes realized by the
chiral edges of two-dimensional topologically ordered phases. The proposed encoding combines the robustness of a gapped topological bulk with the flexibility of gapless edge conformal field theories. To characterize its robustness, we study coherent-information loss under local erasure. We derive an exact expression relating coherent-information loss to relative
entropy, reducing the recoverability problem to universal properties of the edge theory. This leads to power-law scaling of coherent-information loss with the size of the erased region. We further show that, for geometrically local erasures near one edge, the two-dimensional
chiral edge code is at least as robust as the dimensionally reduced CFT code, and is strictly more robust in several representative examples. For Abelian code subspaces, we further construct a power-law-range recovery map supported on the erased region together with a power-law-range buffer; this recovery map depends only on the code subspace, not on the unknown encoded state. We provide numerical calculations for
lattice realizations of compact free
boson and Ising CFT examples that support the theoretical predictions of the power-law exponents.
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All authors Yuntai Song, Zejun Liu, Zhencheng Wang, Jong Yeon Lee, Bowen Shi
Mesoscale and Nanoscale Physics
Anyon-Impurity Bound States in Quantum-Engineered Fractional Chern Insulators
Botao Wang, Amit Vashisht, Felix A. Palm et al. (+3 more)
Mobile
impurities provide a powerful means of probing correlated and topological
quantum matter, through their dressing by the surrounding medium and the practical probes granting access to the resulting composite object. Motivated by the recent observation of anyon-
impurity composites in the solid state, as well as recent realizations of Laughlin-type states in engineered
lattice systems, we investigate the formation of a bound state between a mobile
impurity and a single pinned quasihole in the interacting Harper-Hofstadter model deep in the fractional Chern
insulator regime. Combining analytical arguments with large-scale numerical simulations, we characterize the structure, energetics, and stability of hybrid anyon-
impurity bound states, and show that their binding energy provides direct access to the fractional charge of the quasihole under conditions that we identify. We further demonstrate that the composite object can be coherently transported by externally steering the quasihole pinning potential. Our results establish a realistic pathway for controlled anyon-
impurity manipulation in
quantum-engineered platforms, enabling experimentally feasible protocols for braiding.
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All authors Botao Wang, Amit Vashisht, Felix A. Palm, Fabian Grusdt, Laurens Vanderstraeten, Nathan Goldman
Mesoscale and Nanoscale Physics
Geometric closure of classical nucleation theory for magnetic-field-controlled nanoparticle size across magnetic classes
Yazeed Tawalbeh and Mauro Fernandes Pereira
Controlling nanoparticle size during synthesis remains a central challenge in nanoscience, particularly in systems where external
magnetic fields are used as continuous control parameters. Existing descriptions of
magnetic-field-assisted nucleation are typically material-specific or rely on computationally intensive atomistic methods. Here, we reformulate classical nucleation theory as a geometrically closed thermodynamic framework by introducing a sphere-packing representation of atomic assembly. This construction establishes a direct link between discrete atomic structure and continuum free-energy contributions under applied
magnetic fields, yielding a field-driven
evolution equation for the critical
nucleus size. The resulting theory provides a unified description of nanoparticle nucleation across superparamagnetic, paramagnetic, and diamagnetic systems within a single formalism. It quantitatively reproduces previously unresolved experimental observations for magnetite and nickel nanoparticles, namely the systematic reduction of mean particle size and narrowing of size distributions with increasing
magnetic field. In the diamagnetic limit, the framework recovers our earlier analytical susceptibility-based description of silver nanoparticles, in which the field-dependent critical radius is governed by the induced-magnetization contribution to the nucleation free energy. Beyond modeling the reduction of mean particle size with increasing
magnetic field, the framework reveals that the narrowing of size distributions emerges naturally from the
curvature of the field-modified free-energy landscape. These results establish
magnetic-field-assisted nucleation as a geometrically constrained thermodynamic process, providing a computationally efficient route for controlling nanoparticle size across distinct
magnetic material classes.
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Mesoscale and Nanoscale Physics
Unconventional Scaling of Electric Hall Effect in Magnetic Weyl Semimetals
Chaoxi Cui, Yilin Han, Run-Wu Zhang et al. (+2 more)
Electric
Hall Effect (EHE), a unique phenomenon in two-dimensional (2D)
magnetic systems, refers to the generation of
Hall current by an out-of-plane electric field $\Ez$. Here, we demonstrate that for 2D
magnetic Weyl semimetals that host doubly degenerate nodal points, the EHE features multiple unconventional scaling laws. At zero temperature, the EHE exhibits a topological $E_F^{-1}$
Fermi-energy scaling. Remarkably, the prefactor of the scaling is determined by the global topological charge of the point without any dependence on the local parameters of the system, leading to a universal and significant enhancement of
Hall response in any species of Weyl points as the
Fermi energy approaches the Weyl point. This significant response enables a weak electric field to be directly converted into a measurable
Hall signal. Surprisingly, this enhanced
Hall response is not diminished by temperature, but evolves into an unconventional logarithmically corrected scaling at finite temperature $\sigma_{xy}\propto\Ez\ln(1/|\Ez|)$ for weak $\Ez$, still yielding a divergent electric-field susceptibility. Thus, our work not only unveils intriguing scaling laws resulting from the interaction between magnetism and
topology, but also suggests a novel scaling-enhanced and temperature-robust mechanism that may enable weak electric-field sensing through a practical and all-electric route.
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All authors Chaoxi Cui, Yilin Han, Run-Wu Zhang, Zhi-Ming Yu, Yugui Yao
Mesoscale and Nanoscale Physics
Beyond Electrons: A Theoretical Framework for Near-Field Radiative Thermal Computing and Neural-Network-Inspired Processing
Hexiang Zhang, Mauro Antezza and Yi Zheng
Near field radiative heat transfer provides a route for information processing in which thermal radiation, rather than charge transport, serves as the physical carrier of signals. Here, we propose and theoretically analyze a programmable near field radiative thermal computing framework in which radiative coupling, phase change nonlinearity, and thermal state
memory are mapped onto neural network inspired operations. The framework is constructed from near field radiative thermal diodes, transistors, and multi terminal logic units separated by nanoscale gaps. Radiative heat flux represents the propagated thermal information, while geometry and material dependent radiative coupling provides physically constrained weighting, and the temperature dependent optical response of phase-change materials enables nonlinear modulation and logic state control. Based on these primitives, we formulate a radiative thermal convolutional network for spatial information processing and a radiative thermal recurrent network for history dependent computation. The recurrent response is associated with radiative feedback, thermal relaxation, and phase change hysteresis, with VO2 providing history dependent short term
memory and GST offering a possible route toward non volatile phase storage. We further distinguish the physical radiative networks from a separate software based inverse identification study, in which recurrent machine-learning models are trained on simulated near field heat flux temperature characteristics to recover structural parameters. By establishing a bottom up connection between fluctuational electrodynamics, radiative thermal logic, programmable thermal states, and neural network inspired computation, this study provides a physically grounded basis for exploring non contact thermal information processing at the near field limit.
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Statistical Mechanics · Cross-listed from quant-ph
Quantum fluctuation relations in first-detection processes
A. Imparato
We derive two
quantum fluctuation relations for systems undergoing repeated projective measurements. These fluctuation relations characterize the work that can be extracted from a
quantum device when a first-detection event triggers a mechanical operation leading to positive work production. The correction to the standard
quantum Jarzynski equality depends logarithmically on the mean first-detection time for the time-reversed dynamics. Application of Jensen's inequality leads to fundamental limits on both the total work involved in the repeated measurements and final mechanical operation, and the extracted work alone. The general case of a device connected to an external environment is also considered.
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Quantum Gases
Quantum transport in a non-Hermitian 1D synthetic lattice: from quantum Zeno reflection to near-perfect absorption
Emmanuel. D. Mercado-Gutiérrez, W. Xu, E. Gvozdiovas et al. (+5 more)
We experimentally explore the absorption of a propagating wavepacket impinging upon a dissipative region in an engineered
quantum system. We employ a 1D non-Hermitian synthetic
lattice with an abrupt interface between dissipative and non-dissipative subchains, using the states of the electronic ground-state hyperfine
manifold in a $^{87}$Rb Bose-Einstein condensate as sites. By tuning the dissipation rate, we observe a progression from ballistic propagation, to near-perfect absorption, to
quantum Zeno reflection. Guided by numerical simulations, we identify that optimal absorption occurs when tunneling and dissipation are properly matched, and find qualitative agreement with an idealized semi-infinite model across all dissipation regimes. Our results establish synthetic
lattices as a versatile
Quantum simulation platform for dissipation-engineered
quantum transport and highlight controlled dissipation as a resource for tailoring
quantum dynamics.
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All authors Emmanuel. D. Mercado-Gutiérrez, W. Xu, E. Gvozdiovas, A. M. Piñeiro, Javier Argüello-Luengo, W. D. Phillips, Q. Zhou, I. B. Spielman
Strongly Correlated Electrons
Neural Flux Attachment: From Bose Condensates to Chiral Topological Matter
Rudik Badalyan, Khachatur G. Nazaryan and Tigran A. Sedrakyan
Can one neural wave function describe both a Bose condensate and a
chiral topological
liquid? We introduce ChernFormer, which combines a fermionic
transformer with a fixed Chern-Simons phase that attaches one statistical
vortex to every particle pair. Each factor changes sign under exchange, so their product is exactly bosonic. The fixed phase changes statistics but not probability, making every bosonic learning problem equivalent to a fermionic one with the same approximation error and overlap. With enough capacity, ChernFormer can approximate any normalizable bosonic wave function on the plane at fixed particle number. A finite, smooth network still vanishes when particles meet, yet this contact hole can shrink while the wave function and condensate fraction approach those of a nodeless condensate. Following the needle-in-a-haystack target-reconstruction
benchmark introduced in \cite{NazaryanGaggioliTengFu2025}, we test ChernFormer on the Kalmeyer–Laughlin ground state and its first two
chiral edge states. The overlap curves stay close to unity through their largest sampled sizes, while independent amplitude and phase maps at $N=20$ for all three states recover both local Laughlin
vortices and the collective edge
vortex. By contrast, a continuous, nonzero product of identical particle-wise factors misses these elementary edge sectors. ChernFormer therefore provides one variational
language for conventional bosonic order and
chiral topological matter.
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Statistical Mechanics
Transport coefficients in hard-sphere fluids: thermodynamic versus kinetic descriptions
Miguel Hoyuelos
A thermodynamic theory for transport coefficients in hard-sphere fluids is developed from a general expression for the Onsager
matrix. The theory predicts the ratio $\sigma/\sigma_{\rm id}$, where $\sigma$ is a transport coefficient and $\sigma_{\rm id}$ denotes its dilute-gas value. This ratio depends exclusively on
equilibrium thermodynamic properties and can therefore be computed directly from the equation of state. Compact expressions are obtained for the thermal conductivity, viscosity, and self-
diffusion coefficient. These expressions quantitatively reproduce simulation data over almost the entire fluid range and, in the case of self-
diffusion, significantly improve upon the predictions of Enskog kinetic theory. The results demonstrate that transport coefficients can be accurately described within a purely thermodynamic framework.
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Materials Science · Cross-listed from physics.optics
Pulse-Duration Control of Subcycle Multiband Electron Dynamics Extends the High-Harmonic Cutoff in a Light-Driven Insulator
Hortense Allegre, Simon V. B. Jensen, Joseph J. Broughton et al. (+7 more)
We demonstrate pathway-selective control of extreme-ultraviolet high-harmonic generation by jointly tuning
laser pulse duration ($5$ - $29$ fs) and intensity ($0.8$ - $74$ TW/cm$^2$). Many-cycle pulses at moderate intensities, $\sim 6$ TW/cm$^2$, promote cumulative carrier transfer over successive optical cycles, progressively accessing higher conduction bands. In contrast, few-cycle, high-intensity, $\sim 22$ TW/cm$^2$, pulses drive subcycle multiband dynamics that reach $25$ - $50$ eV
photon energies before decoherence can suppress coherent emission. These results reveal pulse duration and intensity as decisive control knobs for high-harmonic emission, opening a route to band-structure-guided pulse design for higher energy extreme-ultraviolet light sources.
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All authors Hortense Allegre, Simon V. B. Jensen, Joseph J. Broughton, Tim Klee, Yan Li, Jon P. Marangos, Nicolas Tancogne-Dejean, Angel Rubio, John W. G. Tisch, Mary R. Matthews