Mesoscale and Nanoscale Physics
Classical to Quantum Diffusive Transport in Atomically Thin Semiconductors Capped with High-k Dielectric
Jaroslaw Pawlowski, Dickson Thian, Repaka Maheswar et al. (+5 more)
The dielectric environment surrounding
semiconductors plays a crucial role in determining device performance, a role that becomes especially pronounced in atomically thin
semiconductors where charge carriers are confined within a few atomic layers and strongly interact with their surroundings. High-k dielectrics, such as hafnium
oxide (HfO2), have been shown to enhance the performance of two-dimensional (2D) materials by suppressing scattering from charged
impurities and
phonons, but most studies to date have focused on room-temperature transistor operation. Their influence on
quantum transport properties at low temperatures remains largely unexplored. In this work, we investigate how capping monolayer molybdenum disulfide (MoS2) with HfO2 modifies its electronic behavior in the
quantum regime. By comparing devices with and without HfO2 capping, we find that uncapped devices exhibit transport dominated by classical diffusive scattering, whereas capped devices show clear Fabry-Perot interference patterns, providing direct evidence of phase-coherent
quantum transport enabled by dielectric screening. To gain further insight, we develop a tight-binding interferometer model that captures the effect of dielectric screening on conductive modes and reproduces the experimental trends. Our findings demonstrate that dielectric engineering provides a powerful route to control transport regimes in TMD devices.
Read the full abstract ▾
All authors Jaroslaw Pawlowski, Dickson Thian, Repaka Maheswar, Chai Jian Wei, Pawan Kumar, Sudhiranjan Tripathy, Hugh O.H. Churchill, Dharmraj Kotekar Patil
Statistical Mechanics · Cross-listed from quant-ph
A Structural Theory of Quantum Metastability: Markov Properties and Area Laws
Thiago Bergamaschi, Chi-Fang Chen and Umesh Vazirani
Statistical mechanics assumes that a
quantum many-body system at low temperature can be effectively described by its Gibbs state. However, many complex
quantum systems exist only as metastable states of dissipative open system dynamics, which appear stable and robust yet deviate substantially from true thermal
equilibrium. In this work, we model metastable states as approximate stationary states of a quasi-local, (KMS)-detailed-balanced master equation representing Markovian system-bath interaction, and unveil a universal structural theory: all metastable states satisfy an area law of mutual information and a Markov property. The more metastable the states are, the larger the regions to which these structural results apply. Therefore, the hallmark correlation structure and noise resilience of Gibbs states are not exclusive to true
equilibrium but emerge dynamically. Behind our structural results lies a systematic framework encompassing sharp equivalences between local minima of free energy, a non-commutative Fisher information, and approximate detailed balance conditions. Our results build towards a comprehensive theory of thermal metastability and, in turn, formulate a well-defined, feasible, and repeatable target for
quantum thermal simulation.
Read the full abstract ▾
Statistical Mechanics · Cross-listed from quant-ph
Quenching, Fast and Slow: Breaking Kibble-Zurek Universal Scaling by Jumping along Geodesics
Thi Ha Kyaw, Guillermo Romero and Gaurav Saxena
A major drawback of adiabatic
quantum computing (AQC) is fulfilling the energy gap constraint, which requires the total
evolution time to scale inversely with the square of the minimum energy gap. Failure to satisfy this condition violates the adiabatic approximation, potentially undermining computational accuracy. Recently, several approaches have been proposed to circumvent this constraint. One promising approach is to use the family of adiabatic shortcut procedures to fast-forward AQC. One caveat, however, is that it requires an additional
Hamiltonian that is very challenging to implement experimentally. Here, we investigate an alternate pathway that avoids any extra
Hamiltonian in the
evolution to fast-forward the adiabatic dynamics by traversing geodesics of a
quantum system. We find that jumping along geodesics offers a striking mechanism to highly suppress the density of excitations in many-body systems. Particularly, for the
spin-$1/2$ XY model, we analytically prove and numerically demonstrate a rate-independent defect plateau, which contrasts with well-established results for the Kibble-Zurek and anti-Kibble-Zurek mechanisms.
Read the full abstract ▾
Strongly Correlated Electrons · Cross-listed from quant-ph
Hardness of recognizing phases of matter
Thomas Schuster, Dominik Kufel, Norman Y. Yao et al. (+1 more)
We prove that recognizing the phase of matter of an unknown
quantum state is
quantum computationally hard. More specifically, we show that the
quantum computational time of any phase recognition
algorithm must grow exponentially in the range of correlations $\xi$ of the unknown state. This exponential growth renders the problem practically infeasible for even moderate correlation ranges, and leads to super-
polynomial quantum computational time in the system size $n$ whenever $\xi = \omega(\log n)$. Our results apply to a substantial portion of all known phases of matter, including
symmetry-breaking phases and
symmetry-protected topological phases for any discrete on-site
symmetry group in any spatial dimension. To establish this hardness, we extend the study of pseudorandom
unitaries (PRUs) to
quantum systems with
symmetries. We prove that symmetric PRUs exist under standard cryptographic
conjectures, and can be constructed in extremely low
circuit depths. We also establish hardness for systems with translation invariance and purely classical phases of matter. A key technical limitation is that the locality of the parent
Hamiltonians of the states we consider is linear in $\xi$; the complexity of phase recognition for
Hamiltonians with constant locality remains an important open question.
Read the full abstract ▾
All authors Thomas Schuster, Dominik Kufel, Norman Y. Yao, Hsin-Yuan Huang
Statistical Mechanics
Kinetic description of one-dimensional stochastic dynamics with small inertia
Denis S. Goldobin, Lyudmila S. Klimenko, Irina V. Tyulkina et al. (+2 more)
We study single-variable approaches for describing
stochastic dynamics with small inertia. The basic models we deal with describe passive Brownian particles and phase elements (phase oscillators, rotators, superconducting Josephson junctions) with an effective inertia in the case of a linear dissipation term and active Brownian particles in the case of a nonlinear dissipation. Elimination of a fast variable (velocity) reduces the characterization of the system state to a single variable and is formulated in four representations: moments, cumulants, the basis of Hermite functions, and the formal cumulant variant of the last. This elimination provides rigorous mathematical description for the overdamped limit in the case of linear dissipation and the overactive limit of active Brownian particles. For the former, we derive a low-dimensional equation system which generalizes the Ott-Antonsen Ansatz to systems with small effective inertia. In the latter case, we derive a Fokker-Planck-type equation with a forced drift term and an effective
diffusion in one dimension, where the standard two-/three-dimensional mechanism is impossible. In the four considered representations, truncated equation chains are demonstrated to be utilitary for numerical simulation for a small finite inertia.
Read the full abstract ▾
All authors Denis S. Goldobin, Lyudmila S. Klimenko, Irina V. Tyulkina, Vasily A. Kostin, Lev A. Smirnov
Strongly Correlated Electrons · Cross-listed from quant-ph
Sitan Chen, Jordan Cotler and Hsin-Yuan Huang
Characterizing
quantum many-body systems is a fundamental problem across physics, chemistry, and materials science. While significant progress has been made, many existing
Hamiltonian learning protocols demand digital
quantum control over the entire system, creating a disconnect from many real-world settings that provide access only through small, local probes. Motivated by this, we introduce and formalize the problem of
quantum probe
tomography, where one seeks to learn the parameters of a many-body
Hamiltonian using a single local probe access to a small subsystem of a many-body thermal state undergoing time
evolution. We address the identifiability problem of determining which
Hamiltonians can be distinguished from probe data through a new combination of tools from algebraic geometry and smoothed analysis. Using this approach, we prove that generic
Hamiltonians in various physically natural families are identifiable up to simple, unavoidable structural
symmetries. Building on these insights, we design the first efficient end-to-end
algorithm for probe
tomography that learns
Hamiltonian parameters to accuracy $\varepsilon$, with query complexity scaling polynomially in $1/\varepsilon$ and classical post-processing time scaling polylogarithmically in $1/\varepsilon$. In particular, we demonstrate that translation- and rotation-invariant nearest-neighbor
Hamiltonians on square
lattices in one, two, and three dimensions can be efficiently reconstructed from single-site probes of the Gibbs state, up to inversion
symmetry about the probed site. Our results demonstrate that robust
Hamiltonian learning remains achievable even under severely constrained experimental access.
Read the full abstract ▾
Disordered Systems and Neural Networks · Cross-listed from quant-ph
Average-case quantum complexity from glassiness
Alexander Zlokapa, Bobak T. Kiani and Eric R. Anschuetz
Glassiness – a phenomenon in physics characterized by a rough free-energy landscape – implies hardness for stable classical
algorithms. For example, it can obstruct constant-time Langevin dynamics and message-passing in random $k$-SAT and max-cut instances. We provide an analogous framework for average-case
quantum complexity showing that a natural family of
quantum algorithms (e.g., Lindbladian
evolution) fails for natural
Hamiltonian ensembles (e.g., random 3-local
Hamiltonians). Specifically, we prove that the standard notion of
quantum glassiness based on replica
symmetry breaking obstructs stable
quantum algorithms for Gibbs sampling, which we define by a Lipschitz temperature dependence in
quantum Wasserstein complexity. Our proof relies on showing that such
algorithms fail to capture a structural phase transition in the Gibbs state, where glassiness causes the Gibbs state to decompose into clusters extensively separated in
quantum Wasserstein distance. This yields average-case lower bounds for constant-time local Lindbladian
evolution and shallow variational
circuits. Unlike mixing time lower bounds, our results hold even when dynamics are initialized from the maximally mixed state. We apply these lower bounds to non-commuting, non-stoquastic
Hamiltonians by showing a glass transition via the replica trick. We find that the ensemble of all 3-local Pauli strings with independent Gaussian coefficients is average-case hard, while providing analytical evidence that the general $p$-local Pauli ensemble is non-glassy for sufficiently large constant $p$, in contrast to its classical (Ising $p$-
spin, always glassy) and fermionic (SYK, never glassy) counterparts.
Read the full abstract ▾
Statistical Mechanics · Cross-listed from quant-ph
Sujay Kazi and Iman Marvian
We study coherence
distillation under time-translation-invariant operations: given many copies of a
quantum state containing coherence in the energy eigenbasis, the aim is to produce a purer coherent state while respecting the time-translation
symmetry. This
symmetry ensures that the output remains synchronized with the input and that the process can be realized by energy-conserving
unitaries coupling the system to a reservoir initially in an energy eigenstate, thereby modeling thermal operations supplemented by a work reservoir or battery. For
qubit systems, we determine the optimal asymptotic fidelity and show that it is governed by the purity of coherence, a measure of asymmetry derived from the right logarithmic derivative (RLD) Fisher information. In particular, we find that the lowest achievable infidelity (one minus fidelity) scales as $1/N$ times the reciprocal of the purity of coherence of each input
qubit, where $N$ is the number of copies, giving this quantity a clear operational meaning. We additionally study many other interesting aspects of the coherence
distillation problem for
qubits, including computing higher-order corrections to the lowest achievable infidelity up to $O(1/N^3)$, and expressing the optimal channel as a boundary value problem that can be solved numerically.
Read the full abstract ▾
Strongly Correlated Electrons
Fractional quantum Hall states under density decoherence
Zijian Wang, Ruihua Fan, Tianle Wang et al. (+2 more)
Fractional
quantum Hall states are promising platforms for topological
quantum computation due to their capacity to encode
quantum information in topologically degenerate ground states and in the fusion space of non-abelian anyons. We investigate how the information encoded in two paradigmatic states, the Laughlin and Moore-Read states, is affected by density decoherence – coupling of local charge density to non-thermal noise. We identify a critical filling factor $\nu_c$, above which the
quantum information remains fully recoverable for arbitrarily strong decoherence. The $\nu=1/3$ Laughlin state and $\nu = 1/2$ Moore-Read state both lie within this range. Below $\nu_c$ both classes of states undergo a decoherence induced Berezinskii-Kosterlitz-Thousless (BKT) transition into a critical decohered phase. For Laughlin states, information encoded in the topological ground state
manifold degrades continuously with decoherence strength inside this critical phase, vanishing only in the limit of infinite decoherence strength. On the other hand,
quantum information encoded in the fusion space of non-abelian anyons of the Moore-Read states remains fully recoverable for arbitrary strong decoherence even beyond the BKT transition. These results lend further support to the promise of non-Abelian FQH states as platforms for topological
quantum computation and raises the question of how errors in such states can be corrected.
Read the full abstract ▾
All authors Zijian Wang, Ruihua Fan, Tianle Wang, Samuel J. Garratt, Ehud Altman
Soft Condensed Matter
Anomalous Diffusion in Driven Electrolytes due to Hydrodynamic Fluctuations
Ramin Golestanian
The
stochastic dynamics of tracers arising from hydrodynamic fluctuations in a driven electrolyte is studied using a self-consistent field-theory framework in all dimensions. A plethora of scaling behaviour that includes two distinct regimes of anomalous
diffusion is found, and the crossovers between them are characterized in terms of the different tuning parameters. A short-time ballistic regime is found to be accessible beyond two dimensions, whereas a long-time diffusive regime is found to be present only at four dimensions and above. The results showcase how long-ranged hydrodynamic interactions can dominate the dynamics of non-
equilibrium steady states in ionic suspensions and produce strong fluctuations despite the presence of Debye screening.
Read the full abstract ▾
Statistical Mechanics · Cross-listed from quant-ph
Random unitaries that conserve energy
Liang Mao, Laura Cui, Thomas Schuster et al. (+1 more)
Random
unitaries sampled from the Haar measure serve as fundamental models for generic
quantum many-body dynamics. Under standard cryptographic assumptions, recent works have constructed
polynomial-size
quantum circuits that are computationally indistinguishable from Haar-random
unitaries, establishing the concept of pseudorandom
unitaries (PRUs). While PRUs have found broad implications in many-body physics, they fail to capture the energy conservation that governs physical systems. In this work, we investigate the computational complexity of generating PRUs that conserve energy under a fixed and known
Hamiltonian $H$. We provide an efficient construction of energy-conserving PRUs when $H$ is local and commuting with random coefficients. Conversely, we prove that for certain translationally invariant one-dimensional $H$, there exists an efficient
quantum algorithm that can distinguish truly random energy-conserving
unitaries from any
polynomial-size
quantum circuit. This establishes that energy-conserving PRUs cannot exist for these
Hamiltonians. Furthermore, we prove that determining whether energy-conserving PRUs exist for a given family of one-dimensional local
Hamiltonians is an undecidable problem. Our results reveal an unexpected computational barrier that fundamentally separates the generation of generic random
unitaries from those obeying the basic physical constraint of energy conservation.
Read the full abstract ▾
All authors Liang Mao, Laura Cui, Thomas Schuster, Hsin-Yuan Huang
Statistical Mechanics · Cross-listed from quant-ph
Laura Cui, Thomas Schuster, Liang Mao et al. (+2 more)
The nature of randomness and complexity growth in systems governed by
unitary dynamics is a fundamental question in
quantum many-body physics. This problem has motivated the study of models such as local random
circuits and their convergence to Haar-random
unitaries in the long-time limit. However, these models do not correspond to any family of physical time-independent
Hamiltonians. In this work, we address this gap by studying the indistinguishability of time-independent
Hamiltonian dynamics from truly random
unitaries. On one hand, we establish a no-go result showing that for any ensemble of constant-local
Hamiltonians and any
evolution times, the resulting time-
evolution unitary can be efficiently distinguished from Haar-random and fails to form a $2$-design or a pseudorandom
unitary (PRU). On the other hand, we prove that this limitation can be overcome by increasing the locality slightly: there exist ensembles of random polylog-local
Hamiltonians in one-dimension such that under constant
evolution time, the resulting time-
evolution unitary is indistinguishable from Haar-random, i.e. it forms both a
unitary $k$-design and a PRU. Moreover, these
Hamiltonians can be efficiently simulated under standard cryptographic assumptions.
Read the full abstract ▾
All authors Laura Cui, Thomas Schuster, Liang Mao, Hsin-Yuan Huang, Fernando Brandao
Disordered Systems and Neural Networks · Cross-listed from quant-ph
When Less is More: Approximating the Quantum Geometric Tensor with Block Structures
Ahmedeo Shokry, Alessandro Santini and Filippo Vicentini
The natural gradient is central in neural
quantum states optimizations but it is limited by the cost of computing and inverting the
quantum geometric tensor, the
quantum analogue of the Fisher information
matrix. We introduce a block-diagonal
quantum geometric tensor that partitions the metric by network layers, analogous to block-structured Fisher methods such as K-FAC. This layer-wise approximation preserves essential
curvature while removing noisy cross-layer correlations, improving conditioning and scalability. Experiments on Heisenberg and frustrated $J_1$-$J_2$ models show faster convergence, lower energy, and improved stability.
Read the full abstract ▾
Materials Science
Trajectory-Dependent Electronic Energy Losses in Ion Range Simulations
Glen P. Kiely, Bruno Semião, Evgeniia Ponomareva et al. (+3 more)
The energy losses of energetic ions in materials depend on both
nuclear and electronic interactions. In channeling geometries, the stopping effect of these interactions can be highly reduced, resulting in deeper ion penetration. Comprehensive, trajectory-dependent models for ion-material interactions are therefore crucial for the accurate prediction of ion range profiles. We present the implementation of a recent electron density-dependent energy-loss model in the efficient molecular dynamics-based MDRANGE code. The model captures ab initio electron dynamics using a parametrized ion energy loss function, based on calculations for explicit trajectories using real-time time-dependent density functional theory. We demonstrate the efficient simulation of trajectory-dependent ion range profiles with this comprehensive model for electronic energy losses. Our results indicate that accurate trajectory-dependent ion range profiles can be simulated using well-fitted parametrizations of this model. This method offers a unique tool for validation of the fitted energy-loss functions using energetic ion ranges, which can be measured experimentally but are beyond the capability of full MD simulations due to the computational expense.
Read the full abstract ▾
All authors Glen P. Kiely, Bruno Semião, Evgeniia Ponomareva, Rafael Nuñez-Palacio, Unna Arpiainen, Andrea E. Sand
Materials Science
Microstructure and phase stability within the AlMoNbTiZr system: design tools and compositional boundaries for a high-entropy alloy
Mariano Casas-Luna, Dalibor Preisler, Jiří Kozlík et al. (+1 more)
This study explores Ti-containing complex concentrated
alloys (CCAs) within the AlMoNbTiZr system, focusing on compositions located in regions of the Bo-Md diagram characterized by low bond order (Bo) and d-orbital energy level (Md). Four
alloys were designed near the line predicting stress-induced martensite formation in conventional Ti
alloys, then cast, annealed at 1200{\deg}C, and water quenched. Their microstructures and phases were analyzed and compared against phase prediction tools commonly applied to high-
entropy alloys (HEAs), namely empirical parameters and CALPHAD simulations. Results highlight the strong influence of chemical affinity, particularly the roles of Al, Mo, and Zr concentrations, on solid-solution stability. A maximum Al content of 10 at% was identified as the threshold for achieving a single-phase microstructure, observed in the 10Al15Mo10Nb35Ti30Zr
alloy. This
alloy exhibited a bcc/b2 structure with high compressive strength (above 1300 MPa), low Young's modulus (28 GPa), and limited strain (<6%), but lacked the transformation-induced strengthening mechanisms expected for Ti
alloys with comparable Bo-Md values.
Read the full abstract ▾
All authors Mariano Casas-Luna, Dalibor Preisler, Jiří Kozlík, Josef Stráský
Materials Science
Enhanced thermal stability of inverted perovskite solar cells by bulky passivation with pyridine-functionalized triphenylamine
Ekaterina A. Ilicheva, Irina A. Chuyko, Lev O. Luchnikov et al. (+11 more)
Despite competitive efficiency compared to Si
solar cells and relevant stability at near room temperatures the rapid degradation at elevated temperatures remains the critical obstacle for exploitation of perovskite photovoltaics. In this work, a 4-(pyridin-4-yl)triphenylamine (TPA-Py) with pyridine anchor group was employed for inter-grain bulk modification of double-cation CsCH(NH2)2PbI3 perovskite absorbers to enhance thermal stability. Through coordination and dipole-dipole interactions, nitrogen-containing fragments (diphenylamine and pyridine) of TPA-Py passivate uncoordinated cations and improve the phase resilience of perovskite films against segregation. This resulted in a power conversion efficiency of 21.3% with a high open-
circuit voltage of 1.14 V. Notable impact of self-assembled monolayer incorporated into the bulk of perovskite film manifested in huge improvement of thermal stability at 85{\deg}C (ISOS-D-2). TPA-Py modification improved extended the T80 lifetime to ~600 h compared to only 200 h for the reference under harsh heating stress in ambient conditions. In-depth analysis using photoinduced voltage transients and admittance spectroscopy after different stress periods revealed the screening of ion migration (0.45 eV) for devices with TPA-Py. This work offers an important understanding of the bulk modification of microcrystalline perovskite absorbers and guide for robust design of bulk and buried interfaces in highly efficient perovskite
solar cells.
Read the full abstract ▾
All authors Ekaterina A. Ilicheva, Irina A. Chuyko, Lev O. Luchnikov, Polina K. Sukhorukova, Nikita S. Saratovsky, Anton A. Vasilev, Luiza Alexanyan, Anna A. Zarudnyaya, Dmitri Yu. Dorofeev, Sergey S. Kozlov, Andrey P. Morozov, Dmitry S. Muratov, Yuriy N. Luponosov, Danila S. Saranin
Materials Science
Ultraviolet optical conductivity, exciton fine-structure and dispersion of freestanding monolayer h-BN
Jinhua Hong, Alberto Guandalini, Weibin Wu et al. (+7 more)
Excitons govern the light-matter interaction in 2D gapped materials with intrinsically large binding energies. In spite of plentiful optical measurements in the visible for semiconducting transition-metal dichalcogenides, we still lack optical-absorption studies of the
exciton structure of insulating 2D materials that requires UV light. Moreover, measurements of the momentum dispersion of
excitons in the vicinity of optical limit are rare owing to low resolutions but hold the key to reveal quasiparticle interactions. To close this gap, we employ high momentum resolution electron energy loss spectroscopy ($q$-EELS) to explore
exciton dispersions of mono- and few-layer hexagonal boron nitride. Surprisingly, we reveal a fine structure of the first bright
exciton dispersion band composed by two features (A and A$'$), visible only at small momentum, not predicted by Bethe-Salpeter calculations. Introducing an optical conductivity approximation (OCA), we extract from the experimental $q$-EELS spectra the ultraviolet (UV) optical conductivity at zero momentum, $\sigma(\omega)$, and discuss the
exciton fine structure in $\sigma(\omega)$, consistent with previous photoluminescence observations. Our findings establish a general methodology to probe the fine structure of
exciton dispersions, providing new insights into
exciton-
phonon sidebands and eventually polarons in low-dimensional materials.
Read the full abstract ▾
All authors Jinhua Hong, Alberto Guandalini, Weibin Wu, Haiming Sun, Fuwei Wu, Shulin Chen, Chao Ma, Kazu Suenaga, Thomas Pichler, Francesco Mauri
Disordered Systems and Neural Networks · Cross-listed from quant-ph
Entanglement Growth from Entangled States: A Unified Perspective on Entanglement Generation and Transport
Chun-Yue Zhang, Zi-Xiang Li and Shi-Xin Zhang
Studies of
entanglement dynamics in
quantum many-body systems have focused largely on initial product states. Here, we investigate the far richer dynamics from initial entangled states, uncovering universal patterns across diverse systems ranging from many-body localization (MBL) to random
quantum circuits. Our central finding is that the growth of
entanglement entropy can exhibit a counter-intuitive non-monotonic dependence on the initial
entanglement in many non-ergodic systems, peaking for moderately entangled initial states. To understand this phenomenon, we introduce a conceptual framework that decomposes
entanglement growth into two mechanisms: “build” and “move”. The “build” mechanism creates new
entanglement, while the “move” mechanism redistributes pre-existing
entanglement throughout the system. Specifically, we demonstrate that MBL dynamics are “move-dominated”, exhibiting a quantitative agreement with a random SWAP
circuit that serves as a model of pure “move” dynamics by uniformly distributing pre-existing
entanglement. This implies that MBL acts as a redistributor of a hidden
entanglement reservoir quantified by the bipartition-averaged
entropy. This “build-move” framework offers a unified perspective for classifying diverse physical dynamics, deepening our understanding of
entanglement propagation and information processing in
quantum many-body systems.
Read the full abstract ▾
Soft Condensed Matter
Impact of protein corona morphology on nanoparticle diffusion in biological fluids: insights from a mesoscale approach
Beatrice Cipriani and Hender Lopez
Nanoparticles (NPs) demonstrate considerable potential in medical applications, including targeted drug delivery and diagnostic probes. However, their efficacy depends on their ability to navigate through the complex biological environments inside living organisms. In such environments, NPs interact with a dense mixture of biomolecules, which can reduce their mobility and hinder
diffusion. Understanding the factors influencing NP
diffusion in these environments is key to improving nanomedicine design and predicting toxicological effects. In this study, we propose a computational approach to model NP
diffusion in crowded environments. We introduce a mesoscale model that accounts for the combined effects of the
Protein Corona (PC) and the crowded medium on NP movement. By including volume-exclusion interactions and modelling the PC both explicitly and implicitly, we identify key macromolecular descriptors that affect NP
diffusion. Our results show that the morphology of the PC can significantly affect the
diffusion of NPs, and the role of the occupied volume fraction and the size ratio between tracers and crowders are analysed. The results also show that approximating large macromolecular assemblies with a hydrodynamic single-sphere model leads to inexact
diffusion estimates. To overcome the limitations of single-sphere representations, a strategy for an accurate parametrization of NP-PC systems using a single-sphere model is presented.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Topological surface magnon-polariton in an insulating canted antiferromagnet
Weixin Li, Rundong Yuan, Fenglin Zhong et al. (+3 more)
Excitation and control of
antiferromagnetic magnon modes lie at the heart of coherent
antiferromagnetic spintronics. Here, we propose a topological surface
magnon-polariton as a new approach in the prototypical magnonic material hematite. We show that in an insulating canted antiferromagnet, where strong-coupled
magnon-
photon modes can be achieved using electrical on-chip layouts, a surface
magnon-polariton mode exists in the gap of the bulk
magnon-
photon bands. The emergence of surface
magnon-polariton mode is further attributed to the nontrivial
topology of bulk
magnon-
photon bands.
Magnon-
photon coupling enhances the Berry
curvature near the anticrossing points, leading to a topological bulk Chern band associated with the surface
magnon-polaritons. Our work provides a general principle for the utilization of optomagnetic properties in antiferromagnets, with an illustration of its experimental feasibility and wide generality as manifested in hematite.
Read the full abstract ▾
All authors Weixin Li, Rundong Yuan, Fenglin Zhong, Bo Peng, Jean-Philippe Ansermet, Haiming Yu
Soft Condensed Matter
Dynamics of individual active elastic filaments with chiral self-propulsion
Chanania Steinbock and Daniel A. Beller
We study the over-damped dynamics of individual one-dimensional elastic filaments subjected to a
chiral active force which propels each point of the filament at a fixed angle relative to the tangent vector of the filament at that point. Such a model is a reasonable starting point for describing the behavior of
polymers such as microtubules in gliding assay experiments. We derive sixth-order nonlinear coupled partial differential equations for the intrinsic properties of the filament, namely, its
curvature and metric, and show that these equations are capable of supporting multiple different stationary solutions in a co-moving frame, i.e.\ that
chiral active elastic filaments exhibit dynamic multi-stability in their shapes. A linear stability analysis of these solutions is carried out to determine which solutions are stable and a brief analysis of the time-dependent approach to stationary shape is considered. Finally, simulations are presented which confirm many of our predictions while also revealing additional complexity.
Read the full abstract ▾
Statistical Mechanics
Nonequilibrium distribution for stochastic thermodynamics
Jean-Luc Garden
We extend the canonical Gibbs distribution, originally formulated for systems at
equilibrium, to systems driven out of
equilibrium. The
stochastic dynamics of a small system are described by a probability distribution over discrete energy levels. Within this framework, we derive a microscopic expression for work and introduce a microscopic definition of
entropy production (defined here in terms of the uncompensated heat of Clausius) during a nonequilibrium
stochastic process. Work and
entropy production share a common origin arising from variations of the system energy. The proposed framework allows us to recover the nonequilibrium work relation and to establish an equivalent identity for the heat exchanged during a work protocol. Finally, we show that the fluctuations of work and heat governed by the extended canonical distribution follow directly from the fluctuation
theorem for
entropy production.
Read the full abstract ▾
Statistical Mechanics · Cross-listed from quant-ph
Maite Arcos, Philippe Faist, Takahiro Sagawa et al. (+1 more)
In thermodynamics, an
agent's ability to extract work is fundamentally constrained by their environment. Traditional frameworks struggle to capture how strategic decision-making under uncertainty, particularly an
agent's tolerance for risk, determines the trade-off between extractable work and probability of success in finite-scale experiments. Here, we develop a framework for nonequilibrium thermodynamics based on
adversarial resource theories, in which work extraction is modeled as an
adversarial game for an
agent extracting work. Within this perspective, we consider a Szilard-type engine as a game isomorphic to Kelly gambling, an information-theoretic model of optimal betting under uncertainty – but with a thermodynamic utility function. Extending the framework to finite-size regimes, we apply a risk-reward trade-off to find an interpretation of the Renyi divergences in terms of extractable work for a given failure probability. By incorporating risk sensitivity via utility functions, we show that the guaranteed amount of work a rational
agent would accept instead of undertaking a risky protocol is given by a Renyi divergence. This provides a unified picture of thermodynamics and gambling, and highlights how generalized free energies emerge from an
adversarial setup.
Read the full abstract ▾
All authors Maite Arcos, Philippe Faist, Takahiro Sagawa, Jonathan Oppenheim
Disordered Systems and Neural Networks
The Phase Diagram for Percolating Free Surfaces in Disordered Assemblies of Faceted Grains
D. J. Priour Jr
Percolation in systems made up of randomly placed impermeable grains is often examined in the context of system spanning clusters of connected solids forming above a relatively low critical grain density $\rho_{c1}$ or networks of interstitial void volumes ceasing to exist above a signficantly higher threshold $\rho_{c2}$. In this work, we interpret these percolation transitions as, respectively, the low and high density boundaries of percolating exposed surfaces which either ensheath clusters of impermeable particles or line tunnel-like voids. Moreover, we find in the thermodynamic limit exposed surfaces are either sheaths or tunnels with a second order phase transition from the former to the latter at a density threshold $\rho_{c*}$ intermediate between $\rho_{c1}$ and $\rho_{c2}$. We calculate critical inclusion densities with a new method which identifies exposed free surfaces in a geometrically exact manner with a computational cost scaling only linearly in the system volume. We obtain $\rho_{c1}$, $\rho_{c2}$, and $\rho_{c*}$ for a variety of grain geometries, including each of the Platonic solids, truncated icosahedra, and structurally disordered inclusions formed from cubes subject to a random sequence of slicing planes. In the case of the latter, we find a limiting value of $5\%$ for the critical porosity at the void percolation threshold as the number of sustained slices per cube becomes large.
Read the full abstract ▾
Superconductivity
Modified Monte Carlo method with the heat bath algorithm for a model cuprate
Yu. D. Panov, V. A. Ulitko, D. N. Yasinskaya et al. (+1 more)
The results of numerical simulation using a modified Monte Carlo method with a heat bath
algorithm for the pseudospin model of cuprates are presented. The temperature phase diagrams are constructed for various degrees of doping and for various parameters of the model, and the effect of local correlations on the critical temperatures of the model cuprate is investigated. It is shown that, in qualitative agreement with the results of the mean field, the heat bath
algorithm leads to a significant decrease in the estimate of critical temperatures due to more complete accounting of fluctuations, and also makes it possible to detect phase inhomogeneous states. The possibility of using machine learning to accelerate the heat bath
algorithm is discussed.
Read the full abstract ▾
All authors Yu. D. Panov, V. A. Ulitko, D. N. Yasinskaya, A. S. Moskvin
Soft Condensed Matter
Flow Coupling Alters Topological Phase Transition in Nematic Liquid Crystals
Jayeeta Chattopadhyay, Simon Guldager Andersen, Kristian Thijssen et al. (+1 more)
We investigate how coupling to fluid flow influences defect-mediated transitions in two-dimensional passive nematic fluids using fluctuating nematohydrodynamic simulations. The system is driven by tuning the fluctuation strength, with increasing (decreasing) fluctuations defining the forward (backward) protocol. In the absence of flow coupling, the transition follows the Berezinskii–Kosterlitz–Thouless (BKT) scenario, governed by reversible binding and unbinding of $\pm 1/2$ defect pairs. When hydrodynamics is included, the outcome is controlled by the flow–
alignment parameter. For non-aligning nematics ($\lambda=0$), the transition remains consistent with BKT. By contrast, for strain-rate–aligning nematics ($\lambda\neq 0$), bend–splay walls emerge, lowering the defect nucleation threshold and preventing sustained recombination: once created, defects remain unbound across the full range of fluctuation strengths in both forward and backward protocols. These results identify flow
alignment as a fundamental control parameter for topological phase behavior and suggest that the canonical BKT transition emerges only in the absence of flow
alignment.
Read the full abstract ▾
All authors Jayeeta Chattopadhyay, Simon Guldager Andersen, Kristian Thijssen, Amin Doostmohammadi
Disordered Systems and Neural Networks
Non-Hermitian many-body localization in asymmetric chains with long-range interaction
Wen Wang, Han-Ze Li and Jian-Xin Zhong
Understanding the relationship between many-body localization and spectra in non-Hermitian many-body systems is crucial. In a one-dimensional clean, long-range interaction-induced non-Hermitian many-body localization system, we have discovered the coexistence of static and dynamic spectral real-complex phase transitions, along with many-body ergodic-localized phase transitions. The phase diagrams of these two types of transitions show similar non-monotonic boundary trends but do not overlap, highlighting properties distinct from conventional disorder-induced non-Hermitian many-body localization. We also propose a potential experimental realization of this model in cold-atom systems. Our findings provide valuable insights for further understanding the relationship between non-Hermitian many-body localization and non-Hermitian spectra in long-range interacting systems.
Read the full abstract ▾
Materials Science
Observation of electromagnons in a monolayer multiferroic
Mohammad Amini, Tiago V. C. Antão, Liwei Jing et al. (+7 more)
Van der Waals multiferroics have emerged as a promising platform to explore novel magnetoelectric phenomena. Recently, it has been shown that monolayer NiI$_2$ hosts robust type-II multiferroicity down to the two-dimensional limit, a
giant dynamical magnetoelectric coupling at terahertz frequencies, and an electrically switchable
spin polarization. These developments present the possibility of engineering ultrafast, low-energy-consumption, and electrically-tunable spintronic devices based on the collective excitations of the multiferroic order, electromagnons. However, the direct visualization of these bosonic modes in real space and within the monolayer limit remains elusive. Here, we report the atomic-scale observation of electromagnons in monolayer NiI$_2$ using low-temperature scanning tunneling microscopy. By tracking the thermal
evolution of the multiferroic phase, we establish the energy scale and resolve coherent in-gap excitations of the
symmetry-broken multiferroic state. Comparison with first-principles and
spin-model calculations reveals that the low-energy modes originate from electromagnon excitations. Spatially resolved inelastic tunneling spectroscopy maps show a stripe-like modulation of the local spectral function at electromagnon energies, matching theoretical predictions. These results provide direct evidence of the internal structure of electromagnons and establish a methodology to probe these modes at the atomic scale, opening avenues for electrically tunable spintronics.
Read the full abstract ▾
All authors Mohammad Amini, Tiago V. C. Antão, Liwei Jing, Ziying Wang, Antti Karjasilta, Robert Drost, Shawulienu Kezilebieke, Jose L. Lado, Adolfo O. Fumega, Peter Liljeroth
Mesoscale and Nanoscale Physics
Dominant scattering mechanisms in the low/high electric field transport in cryogenic 2D confinement in Silicon (110) with high-$\kappa$ oxides
Hsin-Wen Huang, Xi-Jun Fang, Edward Chen et al. (+1 more)
The performance of silicon nano-devices at cryogenic temperatures is critical for
quantum qubit control
circuits and space applications. Using multi-valley Monte Carlo simulations, we investigate electron transport in Si~(110) systems. At low electric fields,
phonon absorption becomes negligible, and mobility is governed by competition between remote Coulomb scattering~(RCS) at low inversion charge density and surface roughness scattering~(SRS) at high density, leading to a mobility peak. High-$\kappa$ dielectrics such as $\mathrm{HfO_2}$ introduce remote
phonon scattering~(RPS), which suppresses mobility. Under high electric fields,
phonon emission dominates at 4~K, limiting velocity enhancement and resulting in limited current improvement
Read the full abstract ▾
All authors Hsin-Wen Huang, Xi-Jun Fang, Edward Chen, Yuh-Renn Wu
Materials Science
Mechanical coupling of polar topologies and oxygen octahedra rotations in PbTiO$_3$/SrTiO$_3$ superlattices
Fernando Gómez-Ortiz, Louis Bastogne, Xu He et al. (+1 more)
PbTiO$_3$/SrTiO$_3$ artificial superlattices recently emerged as a prototypical platform for the emergence and study of polar
topologies. While previous studies mainly focused on the polar textures inherent to the ferroelectric PbTiO$_3$ layers, the oxygen octahedra rotations inherent to the paraelectric SrTiO$_3$ layers have attracted much little
attention. Here, we highlight a biunivocal relationship between distinct polar
topologies – including $a_1/a_2$ domains, polar
vortices, and skyrmions – within the PbTiO$_3$ layers and specific patterns of oxygen octahedra rotations in the SrTiO$_3$ layers. This relationship arises from a strain-mediated coupling between the two materials and is shown to be reciprocal. Through second-principles atomistic simulations, we demonstrate that each polar texture imposes a corresponding rotation pattern, while conversely, a frozen oxygen octahedra rotation dictates the emergence of the associated polar state. This confirms the strong coupling between oxygen octahedra rotations in SrTiO$_3$ and polarization in PbTiO$_3$, highlighting their cooperative role in stabilizing complex polar textures in related superlattices.
Read the full abstract ▾
All authors Fernando Gómez-Ortiz, Louis Bastogne, Xu He, Philippe Ghosez