Mesoscale and Nanoscale Physics
Fast spectral solver for viscoelastic structures under oscillatory flow in free space or wall-bounded domains: applications to quartz crystal microbalance and force spectroscopy
Pablo Palacios Alonso, Raúl Pérez Peláez and Rafael Delgado-Buscalioni
We present a fast spectral solver for the linear response of viscoelastic structures under oscillatory flow either in free space or close to a flat moving wall. The scheme works in the frequency domain (using phasors) and couples the oscillatory Stokes equation with rigid or flexible structures, modeled by viscoelastic networks of immersed boundary kernels. The fluid-structure coupling can be solved by two routes. One route calculates the hydrodynamic mobility
matrix required to solve the equation for the structure deformation rate in
matrix form. The second route iteratively solves the coupled fluid-structure equations: fluid-induced forces on the structures create a tension field which is then transferred to the fluid, until convergence. The resulting fixed-point problem is solved iteratively using the Anderson acceleration method. The mobility route is optimal when dealing with one or few structures, while the iterative scheme is preferred for denser dispersions. In any case, the flow resulting from the body forces is solved by a recently developed scheme [J. Fluid. Mech. 1010 A57, 2025] which is spectral in space and time and deals with doubly periodic open domains (either free-space or wall-bounded) where meshing is restricted to the region of interest around the structures. We test the present scheme in two applied contexts: quartz-
crystal-microbalance (QCM) of spheres, suspended, adsorbed or tethered to viscoelastic linkers; and force spectroscopy (via atomic force microscopy) reproducing the power spectra of vibrating microparticles near a solid boundary. In all cases, comparisons with analytical, numerical and experimental results show excellent agreement. We conclude by discussing new routes the scheme opens in force spectroscopy and QCM analyses of soft objects.
Read the full abstract ▾
Materials Science · Cross-listed from cs.LG
Benchmarking GNNs for OOD Materials Property Prediction with Uncertainty Quantification
Liqin Tan, Pin Chen, Menghan Liu et al. (+3 more)
We present MatUQ, a
benchmark framework for evaluating graph neural networks (GNNs) on out-of-distribution (OOD) materials property prediction with uncertainty quantification (UQ). MatUQ comprises 1,375 OOD prediction tasks constructed from six materials
datasets using five OFM-based and a newly proposed structure-aware splitting strategy, SOAP-LOCO, which captures local atomic environments more effectively. We evaluate 12 representative GNN models under a unified uncertainty-aware training protocol that combines Monte Carlo Dropout and Deep Evidential Regression (DER), and introduce a novel uncertainty metric, D-EviU, which shows the strongest correlation with prediction errors in most tasks. Our experiments yield two key findings. First, the uncertainty-aware training approach significantly improves model prediction accuracy, reducing errors by an average of 70.6% across challenging OOD scenarios. Second, the
benchmark reveals that no single model dominates universally: earlier models such as SchNet and ALIGNN remain competitive, while newer models like CrystalFramer and SODNet demonstrate superior performance on specific material properties. These results provide practical insights for selecting reliable models under distribution shifts in materials discovery.
Read the full abstract ▾
All authors Liqin Tan, Pin Chen, Menghan Liu, Xiean Wang, Jianhuan Cen, Qingsong Zou
Materials Science
Control of Extraordinary Optical Transmission in Resonant Terahertz Gratings via Lateral Depletion in an AlGaN-GaN Heterostructure
Geofrey Nyabere, Hunter Ellis, Miguel Gomez et al. (+7 more)
Periodic metallic gratings on substrates can support a range of electromagnetic modes, such as leaky waveguide, guided-resonant, and Fabry-Perot (FP) cavity modes, which can strongly modulate optical transmission under resonant excitation. Here, we investigate how this coupling can be dynamically manipulated through charge-density control in a laterally patterned AlGaN/GaN
heterostructure. The structure comprises metallic stripes separated by regions containing a two-dimensional electron gas (2DEG), forming a periodically modulated interface whose electromagnetic response is governed by the charge density between the stripes. In the unbiased state, the conductive 2DEG screens the incident terahertz field and suppresses excitation of guided modes. When the 2DEG is depleted, the change in boundary conditions allows efficient coupling into substrate resonances, producing a strong modulation at particular frequencies where extraordinary optical transmission (EOT) through the structure takes place. The results highlight the sensitive dependence of guided-mode-resonance (GMR) mediated EOT on inter-stripe charge distribution and demonstrate a direct interplay between carrier dynamics and resonant electromagnetic phenomena in the terahertz regime.
Read the full abstract ▾
All authors Geofrey Nyabere, Hunter Ellis, Miguel Gomez, Wei Jia, Yizheng Liu, Karli Ann Higley, Sriram Krishnamoorthy, Steve Blair, Kai Fu, Berardi Sensale-Rodriguez
Materials Science
Cryogenic UV detection using stress-engineered zero-bias ZnO-thin film based Piezo-Photonic detector
P. Sau, N. Hancock, I. Tzoka et al. (+6 more)
We demonstrate a zero-bias ultraviolet (UV) detector using zinc
oxide (ZnO) thin films as the active
semiconductor layer, specifically for application in cryogenic conditions. The zero-bias device utilizes the piezoelectric potential developed through interfacial stress in the active
semiconductor layer for charge transport. We explored two vertically stacked metal-
semiconductor-metal (MSM) configurations: Sample I, a device comprised of chromium (Cr)/ZnO/Cr layers, and Sample II, a ZnO-silicon nitride (Si3N4) device comprised of Cr/Si3N4/ZnO/Cr layers. The Si3N4 layer in Sample II was introduced in the form of pillars, with the aim of increasing the residual stress in the active region. These fabricated devices were tested at both room and cryogenic temperatures to characterize their UV-detection performance in a custom test stand using a 365 nm UV LED source. We observe a higher UV-induced voltage signal for Sample II in comparison to Sample I at both temperature regimes. Grazing-incidence X-ray diffraction (GIXRD) measurements showed approximately 40% higher residual stress in Sample II than in Sample I. A higher residual stress suggests a higher induced piezopotential in Sample II, explaining the enhancement in the UV-induced signal. Our results demonstrate that through appropriate in-device stress engineering, UV photoinduced signals can be enhanced, increasing detector sensitivity. A zero-bias photodetector with in-device stress engineering, as demonstrated here, can have applications in extreme environments, like cryogenic
liquid noble elements or high radiation space environments, where low or zero-power detection may be required.
Read the full abstract ▾
All authors P. Sau, N. Hancock, I. Tzoka, V. Khichar, A. Barajas, G. Gansle, N. Hozhabri, V.A. Chirayath, J. Asaadi
Mesoscale and Nanoscale Physics
Impact of Contact Gating on Scaling of Monolayer 2D Transistors Using a Symmetric Dual-Gate Structure
Victoria M. Ravel, Sarah R. Evans, Samantha K. Holmes et al. (+4 more)
The performance and scalability of two-dimensional (2D) field-effect transistors (FETs) are strongly influenced by geometry-defined electrostatics. In most 2D FET studies, the gate overlaps with the source and drain electrodes, allowing the gate potential to modulate the 2D
semiconductor underneath the electrodes and ultimately effect carrier transport at the metal-
semiconductor interface - a phenomenon known as contact gating. Here, a symmetric dual-gate structure with independently addressable back and top gates is employed to elucidate the impact of contact gating on a monolayer MoS2 channel. Unlike previous studies of contact gating, this symmetric structure enables quantification of the phenomena through a contact gating factor, revealing a 2x enhancement in on-state performance in long-channel devices. At scaled dimensions (50 nm channel and 30 nm contact length), the influence of contact gating becomes amplified, yielding a 5x increase in on-state performance and a 70% reduction in transfer length when contact gating is present. Since many reported record-performance 2D FETs employ back-gate geometries that inherently include contact gating, these results establish contact gating as a critical and previously underappreciated determinant of device performance in the 2D FET landscape.
Read the full abstract ▾
All authors Victoria M. Ravel, Sarah R. Evans, Samantha K. Holmes, James L. Doherty, Md Sazzadur Rahman, Tania Roy, Aaron D. Franklin
Soft Condensed Matter
Marco Musacchio, Alexander P. Antonov, Hartmut Löwen et al. (+1 more)
We study a
crystal composed of active units governed by self-
alignment and chirality. The first mechanism acts as an effective torque that aligns the particle orientation with its velocity, while the second drives individual particles along circular orbits. We find that even a weak degree of chirality, when coupled with self-
alignment, induces collective motion of the entire
crystal along circular trajectories in space. We refer to this phase as a circling
crystal. When chirality outweigh self-
alignment, the circular global motion is suppressed in favor of
vortex-like regions of coordinated motion. This state is characterized by oscillating spatial velocity correlations, a power law decay of the energy spectrum, and oscillatory temporal correlations. Our findings can be tested experimentally in systems ranging from epithelial tissues to swarming
robots, governed by chirality and self-
alignment.
Read the full abstract ▾
All authors Marco Musacchio, Alexander P. Antonov, Hartmut Löwen, Lorenzo Caprini
Strongly Correlated Electrons · Cross-listed from quant-ph
Local arrows of time in quantum many-body systems
Andrew G. Yates, Jordan Cotler, Nishad Maskara et al. (+1 more)
We demonstrate that in
quantum many-body systems, local arrows of time can differ from the global time $t$ induced by
Hamiltonian evolution. That is, within a
quantum many-body system, the flow of time can be relative to each observer or by proxy each local subsystem. We provide a definition of local arrows of time in
quantum many-body systems, and explain their relation to spacetime
quantum entropies. Then we give a variety of numerical and analytical examples which explore different ways in which local arrows of time can manifest in
quantum many-body dynamics, including exotic arrows of time arising from
quantum thermalization and
quantum error correction.
Read the full abstract ▾
All authors Andrew G. Yates, Jordan Cotler, Nishad Maskara, Mikhail D. Lukin
Materials Science
A Brief Perspective on Piezotronic and Thermoelectric Coupling: Flexible Platforms for Synergistic Energy Scavenging and Peltier-Caloric Effects
David Carroll and ChaoChao Dun
Advances in the development of flexible piezoelectric and thermoelectric materials have provided an important avenue for the exploration of energy scavenging through the thermodynamic-coupling of orthogonal energy-scavenging modalities. This has led to a body of work creating hybrid thermo/piezo-electric generator devices (T/PEGs) in which the two effects become thermodynamically entangled. Based on hetero- thin film architectures, such devices can exhibit a surprising power generation characteristic which is non-additive between the two energy-scavenging effects. For example, when the thermoelectric and piezoelectric effects are strongly coupled by their proximal fields, the efficacy of energy scavenging can be made to exceed that of the two effects independently. In this review of such effects, a basic coupled heat engine model is shown to provide insight into the origins of synergistic power generation. These models however, suggest the emergence of other combined thermodynamic properties such as the kinetic Peltier-Caloric Effect (PCE) traced to Onsager reciprocity. The recent observation of this effect in multicomponent systems is confirmation of the limited perspective of thermodynamic separability.
Read the full abstract ▾
Materials Science
An optically enhanced crystalline silicon allotrope: hydrogen passivated type II silicon clathrate
Yinan Liu, Joseph P. Briggs, Sam Saiter et al. (+7 more)
While Si clathrates have been explored as promising direct bandgap
semiconductors, their practical optoelectronic performance has been limited by high doping levels and structural defects. Hydrogen has long been used to improve the optoelectronic quality of conventional Si, yet its role in clathrate structures remains unexplored. In this study, we demonstrate that hydrogen (deuterium) can be incorporated into type II Si clathrate framework using remote
plasma treatment. This process leads to the formation of NaD and SiD complexes, which significantly reduce both the Na donor density and dangling bond defects. Electron paramagnetic resonance confirms nearly a tenfold decrease in Na-related donor states, resulting in the lowest doping level reported in Si clathrates to date. Following passivation, the integrated photoluminescence intensity increases by a factor of 40, accompanied by a blue shift of the main emission peak, consistent with a transition closer to the intrinsic band edge. A new emission peak at 930 nm, attributed to hydrogen-related recombination centers, also appears. These improvements remain stable up to 400 oC. Altogether, this work establishes hydrogen passivation as a viable strategy for enhancing light emission in Si clathrates and opens a new pathway toward their application in Si-based light-emitting diodes and other direct-bandgap optoelectronic devices.
Read the full abstract ▾
All authors Yinan Liu, Joseph P. Briggs, Sam Saiter, Meenakshi Singh, Carolyn A. Koh, P. Craig Taylor, Michael Walker, Khalid Mateen, Moussa Kane, Reuben T. Collins
Materials Science
Structure of Antiphase boundaries in Ni-M-Ga: multiscale modelling
Jan Zemen, František Máca, Václav Drchal et al. (+2 more)
Antiphase boundaries (APBs) are ubiquitous in ordered Heusler
alloys and strongly influence
magnetic coercivity in Ni-Mn-Ga, yet the link between their atomic-scale exchange interactions and micrometer-scale
magnetic contrast measured by
magnetic force microscopy (MFM) remains unclear. We combine density functional theory (DFT) and finite-element magnetostatics to bridge these scales in Ni-Mn-Ga. DFT calculations on supercells containing planar APBs show that the lowest-energy configuration comprises a pair of parallel APBs enclosing a nanoscale region - only three Mn-Ga atomic layers thick - whose magnetization is antiparallel to the surrounding
matrix due to strong
antiferromagnetic exchange across each APB (in contrast to
ferromagnetic coupling in bulk martensite). According to our magnetostatic finite element model, this thin region with antiparallel magnetization generates the characteristic MFM contrast extending approx. 100 nm from the APB pair. When the APBs are further apart than 50 nm, dipole-dipole penalties outweigh exchange gains, preventing formation of an extended antiparallel domain, in agreement with experimental evidence. These results identify APB pairs as the origin of the observed MFM contrast and offer an interpretation of the modest strengths of domain-wall pinning by APBs, informing the design of
magnetic shape-
memory alloys with tailored coercivity.
Read the full abstract ▾
All authors Jan Zemen, František Máca, Václav Drchal, Martin Veis, Oleg Heczko
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Temperature-dependent excitonic light manipulation with atomically-thin optical elements
Ludovica Guarneri, Qitong Li, Thomas Bauer et al. (+5 more)
Monolayer 2D
semiconductors, such as WS2, exhibit uniquely strong light-matter interactions due to
exciton resonances that enable atomically-thin optical elements. Similar to geometry-dependent plasmon and Mie resonances, these intrinsic material resonances offer coherent and tunable light scattering. Thus far, the impact of the
excitons temporal dynamics on the performance of such excitonic metasurfaces remains unexplored. Here, we show how the excitonic decay rates dictate the focusing efficiency of an atomically-thin lens carved directly out of exfoliated monolayer WS2. By isolating the coherent
exciton radiation from the incoherent background in the focus of the lens, we obtain a direct measure of the role of
exciton radiation in wavefront shaping. Furthermore, we investigate the influence of
exciton-
phonon scattering by characterizing the focusing efficiency as a function of temperature, demonstrating an increased optical efficiency at cryogenic temperatures. Our results provide valuable insights in the role of excitonic light scattering in 2D nanophotonic devices.
Read the full abstract ▾
All authors Ludovica Guarneri, Qitong Li, Thomas Bauer, Jung-Hwan Song, Ashley P. Saunders, Fang Liu, Mark L. Brongersma, Jorik van de Groep
Quantum Gases
Mediated interactions in mixtures of ultracold atoms
Henry Ando, Geyue Cai, Cheng Chin et al. (+1 more)
We describe recent theoretical and experimental developments on mediated interactions in mixtures of bosonic and fermionic atoms. We discuss how particle-hole excitations of a
Fermi sea can induce long-range interactions between heavy
impurities or atoms in a Bose-Einstein condensate. Conversely,
phonon excitations of a Bose-Einstein condensate induce interactions between fermionic atoms. These mediated interactions exhibit different short-range and long-range scaling regimes with distance and, if strong enough, can induce
fermion superfluidity. We discuss the prospects for observing new phenomena that could arise from mediated interactions. Experimentally, we outline recent studies of the 133Cs-6Li Bose-
Fermi mixture, a platform well-suited for investigating
fermion-mediated interactions. A Cs Bose-Einstein condensate immersed in a degenerate Li
Fermi gas is prepared with tunable interspecies interactions. In the weak-coupling regime, precision measurements of condensate properties reveal
fermion-mediated attractions between
bosons, matching theoretical predictions. In the strong-coupling regime, we observe suppression and revival of sound modes and novel many-body resonances. Altogether, we aim to highlight both instances where experiment and theory agree well, and promising prospects to engineer long-range interactions in atomic
quantum gases.
Read the full abstract ▾
All authors Henry Ando, Geyue Cai, Cheng Chin, Tilman Enss
Mesoscale and Nanoscale Physics · Cross-listed from hep-th
Geometry Induced Chiral Transport and Entanglement in $AdS_2$ Background
Kazuki Ikeda and Yaron Oz
We study the real-time
chiral dynamics of Dirac
fermions in AdS$_2$ and AdS$_2$ black hole backgrounds. The spacetime
curvature generates a
spin connection term, acting as an effective
magnetic field and a position-dependent
chiral chemical potential. This leads to strongly asymmetric wave propagation, confined within an inhomogeneous Lieb-Robinson cone. The front velocities decrease with increasing
fermion mass and horizon radius. The
entanglement entropy grows inside the causal cone, and it saturates due to screening/dephasing in the finite inhomogeneous chain. In dipole-dipole collision, the central bipartite
entropy rises when the inward Lieb-Robinson fronts intersect, forming a bright ridge in the local
entanglement profile. Charge and current correlators peak at the front arrival, providing a real-time diagnostic of
chiral transport. These results establish a causality-respecting framework, linking
curvature and horizons to transport and
entanglement in (1+1)-dimensional fermionic matter.
Read the full abstract ▾
Materials Science
Controlling Metastability through Annealing of High-Entropy Nanoalloy Electrocatalysts to Boost Performance towards the Oxygen Evolution Reaction
Varatharaja Nallathambi, Aneeta Jose Puthussery, Andrea M. Mingers et al. (+7 more)
Low-cost transition metal high-
entropy nanoalloys are emerging as sustainable alternatives to platinum group electrocatalysts. Synthesis conditions of single-phase solid solutions can alter phase stability, causing surface composition changes that affect electrocatalytic performance. Here, we propose to exploit the metastability of carbon-doped Cantor
alloy-based amorphous high-
entropy alloy nanoparticles produced by nanosecond-pulsed
laser synthesis in organic solvents. In situ electron microscopy reveals crystallization and partitioning of elements upon heating to 600 {\deg}C, forming heterostructured nanoparticles with reinforced carbon shells that exhibit a 5- to 7-fold enhancement of the electrocatalytic activity compared to the as-synthesized counterparts for the oxygen
evolution reaction. We demonstrate the strategic utilization of phase metastability in high-
entropy nanoalloys through post-synthesis annealing to enhance the electrochemical activity of
laser-generated nanoparticles.
Read the full abstract ▾
All authors Varatharaja Nallathambi, Aneeta Jose Puthussery, Andrea M. Mingers, Robert Stuckert, André Olean-Oliveira, Sven Reichenberger, Dierk Raabe, Viktor Čolić, Baptiste Gault, Stephan Barcikowski
Disordered Systems and Neural Networks
High-dimensional dynamical systems: co-existence of attractors, phase transitions, maximal Lyapunov exponent and response to periodic drive
Samantha J. Fournier and Pierfrancesco Urbani
We study the dynamical properties of a broad class of high-dimensional random dynamical systems exhibiting chaotic as well as fixed point and periodic attractors. We consider cases in which attractors can co-exists in some regions of the phase diagrams and we characterize their nature by computing the maximal Lyapunov exponent. For a specific choice of the dynamical system we show that this quantity can be computed explicitly in the whole chaotic phase due to an underlying integrability of a properly defined Schrödinger problem. Furthermore, we consider the response of this dynamical systems to periodic perturbations. We show that these dynamical systems act as filters in the frequency-amplitude spectrum of the periodic forcing: only in some regions of the frequency-amplitude plane the periodic forcing leads to a synchronization of the dynamics. All in all, the results that we present mirror closely the ones observed in the past forty years in the study of standard models of random recurrent neural networks. However, the dynamical systems that we consider are easier to study and we believe that this may be an advantage if one wants to go beyond random dynamical systems and consider specific training strategies.
Read the full abstract ▾
Materials Science
Time-Dependent Oxidation and Scale Evolution of a Wrought Co/Ni-based Superalloy
Cameron. Crabb, Zachary. T. Kloenne, Samuel. R. Rogers et al. (+4 more)
Understanding how protective
oxide scales evolve over time is necessary for improving the long term resistance of superalloys. This work investigates the time-dependent oxidation behavior of an ingot-processable Co/Ni-based superalloy oxidized in air at $800~^\circ\mathrm{C}$ for $20$, $100$, and $1000~\mathrm{h}$ . Mass-gain and white-light interferometry measurements quantified oxidation kinetics, surface roughness, and spallation, while high-resolution STEM-EDX characterized
oxide morphology and nanoscale elemental partitioning. Atom probe
tomography captured the key transition regions between the chromia and alumina scales, and X-ray diffraction was used to identify a gradual transition from NiO and (Ni,Co)-spinel phases to a compact, dual phase chromia and alumina-rich scale. The oxidation rate evolved from near-linear to
parabolic behavior with time, consistent with
diffusion-controlled growth once a continuous Cr$_2$O$_3$/$\alpha$-Al$_2$O$_3$ scale formed. These observations help link kinetics, structure and chemistry, showing how an originally porous spinel layer transforms into a dense, adherent chromia + alumina scale that provides long-term protection in wrought Co/Ni-based superalloys.
Read the full abstract ▾
All authors Cameron. Crabb, Zachary. T. Kloenne, Samuel. R. Rogers, Chi-Hang. D. Kwok, Mark. C. Hardy, Michelle. S. Conroy, David. Dye
Materials Science
pH Regulates Ion Dynamics in Carboxylated Mixed Conductors
Zeyuan Sun, Mengting Sun, Rajiv Giridharagopal et al. (+12 more)
Coupled ionic and electronic transport underpins processes as diverse as electrochemical energy conversion, biological signaling, and soft adaptive electronics. Yet, how chemical environments such as pH modulate this coupling at the molecular scale remains poorly understood. Here, we show that the protonation state of carboxylated polythiophenes provides precise chemical control over ion dynamics, doping efficiency, solvent uptake and mechanical response. The findings establish molecular acidity as a general strategy to program ionic preference and mechanical stability, offering design principles for pH-responsive mixed conductors and soft electronic materials that couple ionic, electronic, and mechanical functionality.
Read the full abstract ▾
All authors Zeyuan Sun, Mengting Sun, Rajiv Giridharagopal, Robert C. Hamburger, Siyu Qin, Haoxuan Li, Mitchell C. Hausback, Yulong Zheng, Bohyeon Kim, Heng Tan, Thomas E. Gartner III, Elizabeth R. Young, Christopher J Takacs, David S. Ginger, Elsa Reichmanis
Mesoscale and Nanoscale Physics
Probing Topological Stability with Nonlocal Quantum Geometric Markers
Quentin Marsal, Hui Liu, Emil J. Bergholtz et al. (+1 more)
Spatially resolved local
quantum geometric markers play a crucial role in the diagnosis of topological phases without long-range translational
symmetry, including amorphous systems. Here, we focus on the nonlocality of such markers. We demonstrate that they behave as correlation functions independently of the material's structure, showing sharp variations in the vicinity of topological transitions and exhibiting a unique pattern in real space for each transition. Notably, we find that, even within the same Altland-Zirnbauer class, distinct topological transitions generate qualitatively different spatial signatures, enabling a refined, class-internal probe of topological stability. As such, nonlocal
quantum geometric indicators provide a more efficient and versatile tool to understand and predict the stability of topological phase transitions.
Read the full abstract ▾
All authors Quentin Marsal, Hui Liu, Emil J. Bergholtz, Annica M. Black-Schaffer
Materials Science
Electrostatic, Luminescent, and Paramagnetic Responses of Fresh BN Nanopowders Synthesized under Concentrated Light
Lina Sartinska
This study explores the properties of nanopowders synthesized under high-temperature, non-
equilibrium conditions in a high-flux optical furnace in a nitrogen flow. Boron powders served as the starting material, and the intense thermal gradients during synthesis led to incomplete chemical reactions. As a result, the surface of the resulting nanoparticles is covered with a thin layer of sassolite, followed by boron
oxides, beneath which lies a boron nitride shell. The subsurface contains boron-rich nitride phases, while the core consists of elemental boron. For reference, commercial platelet-like h-BN powders from the "Chempur" company were also analyzed. Initially, all synthesized nanopowders displayed pronounced electrostatic charging, photoluminescence (PL), and paramagnetic activity, attributable to high surface defect densities and unsaturated chemical bonds. However, after two years of exposure to ambient air, these nanopowders exhibited complete loss of electrostatic charging, absence of photoluminescence (PL), and disappearance of the characteristic single EPR resonance line. Similarly, commercial h-BN nanopowder from the "Chempur" company does not exhibit a single EPR resonance line too. FTIR analysis revealed progressive surface oxidation and hydroxylation of this powder, suggesting that atmospheric moisture and oxygen effectively passivated defect states. These findings underscore the critical role of surface chemistry in governing the electrostatic, optical, and
magnetic behavior of BN-based nanomaterials and highlight the importance of defect stabilization for preserving functional properties over time.
Read the full abstract ▾
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Yang Peng
We introduce a non-abelian
geometric quantum energy pump realized by a transitionless
geometric quantum drive–a time-dependent
Hamiltonian supplemented by a counterdiabatic term generated by a prescribed trajectory on a smooth control
manifold–that coherently transports states within a degenerate subspace. When the coordinates of the trajectory are independently addressable by external drives, the net energy transferred between drives is set by the non-abelian Berry-
curvature tensor. The trajectory-averaged pumping power is separately controlled by the initial state and by the
Hamiltonian topology through the Euler class. We outline an implementation with artificial atoms, which are realizable on various platforms including trapped atoms/ions, superconducting
circuits, and
semiconductor quantum dots. The resulting energy pump can serve as a
quantum transducer or charger, and as a metrological tool for measuring phase coherences in
quantum states.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Green Function Invariants for Floquet Topological Superconductivity Induced by Proximity Effects
Mohamed Assili and Panagiotis Kotetes
We bring forward a Green function approach for the prediction of Floquet topological phases in driven
superconductor-
semiconductor hybrids. Although it is common to treat the superconducting component as a mere Cooper-pair reservoir, it was recently pointed out that such an approximation breaks down in the presence of driving, due to the emergence of level broadening. Here, we go beyond these recent works and prescribe how to construct the Floquet topological invariants for such driven hybrids. Specifically, we propose to first obtain the midgap quasi-energy spectra by including the hermitian part of the
semiconductor's self-energy and, subsequently, read out the respective level broadenings by projecting the anti-hermitian part of the self-energy onto the quasi-energy eigenvectors. We exemplify our approach for a Rashba nanowire coupled to a
superconductor and a time-dependent Zeeman field. Using our method, we obtain the Floquet band structure, the respective level broadenings, and the topological invariants. Our analysis reinforces the need to properly account for the self-energy, and corroborates that broadening effects can hinder the observation of the Floquet topological phases and especially of those harboring Majorana $\pi$ modes.
Read the full abstract ▾
Quantum Gases
Functional renormalization group study of a dissipative Bose–Hubbard model
Oscar Bouverot-Dupuis, Vincent Grison and Nicolas Paris
We investigate the phase diagram of a one-dimensional dissipative Bose-Hubbard model using the nonperturbative functional renormalization group (FRG). Each
lattice site is coupled to an independent bath, generating long-range temporal interactions that encode non-Markovian dissipation. For a broad class of bath spectra - ohmic, sub-ohmic, and super-ohmic - we identify two competing low-energy regimes: a Luttinger-
liquid line of fixed points and a dissipative fixed point characterized by finite compressibility, vanishing superfluid stiffness, and universal scaling exponents, separated by a Berezinskii-Kosterlitz-Thouless transition. The FRG framework is essential here, as it provides access to the complete renormalization group flow and all fixed points from a single microscopic action, beyond the reach of perturbative or variational methods. This work establishes a unified and systematically improvable framework for describing dissipative
quantum phases in one dimension.
Read the full abstract ▾
Strongly Correlated Electrons
Nonequilibrium Probes of Quantum Geometry in Gapless Systems
Bastien Lapierre, Per Moosavi and Blagoje Oblak
Much of our understanding of gapless
quantum matter stems from low-energy descriptions using conformal field theory. This is especially true in 1+1 dimensions, where such theories have an infinite-dimensional parameter space induced by their conformal
symmetry. We reveal the underlying
quantum geometry by considering finite many-body systems driven by time-dependent conformal transformations. For small deformations, perturbation theory predicts absorption rates and linear responses that probe the
quantum geometric tensor. For arbitrarily large but adiabatic deformations, we show that periodic drives give rise to nontrivial return amplitudes involving the
quantum metric, beyond the familiar leading order that only features a Berry phase. The former is less sensitive to decoherence than the latter, so it can provide robust experimental signatures of our predictions. Our field-theoretic findings are universal, comprising general relations between measurable quantities and
quantum geometry that only depend on the emergent effective description. This is supported both by numerical simulations of gapless
lattice models, and by exact results for
quantum dynamics under certain Floquet drives, probing the full dynamical parameter space.
Read the full abstract ▾
Statistical Mechanics · Cross-listed from quant-ph
Harmonic Control of Dynamical Freezing in Programmable Rydberg Atom Arrays
Madhumita Sarkar, Ben Zindorf, Bhaskar Mukherjee et al. (+2 more)
Periodic driving enables the engineering of complex
quantum matter, yet in interacting systems it generically leads to energy absorption, which limits the lifetime of the engineered states. To address this challenge, dynamical freezing has been proposed as a mechanism for stabilizing non-
equilibrium states over parametrically long timescales. While theory predicts robust freezing under simplifying assumptions, realistic platforms inevitably include additional interaction processes that alter its stability. Here, we report the experimental observation of dynamical freezing in programmable Rydberg atom arrays of up to 100 atoms in one and two dimensions. We find that while single-frequency driving produces pronounced suppression of excitation dynamics, the freezing behavior is restricted to a narrow parameter regime due to interaction-induced heating channels present in realistic simulators. Using a perturbative Floquet analysis of the fully interacting atomic system, we identify the dominant microscopic heating processes responsible for this destabilization. Leveraging this understanding, we design a dual-parameter modulation of detuning and Rabi frequency that coherently cancels these absorption pathways and substantially broadens the freezing regime, making it also robust across different geometries. Our results reveal how heating processes shape the stability of dynamical freezing in interacting Floquet systems and demonstrates a route to control driven many-body dynamics in realistic experimental platforms.
Read the full abstract ▾
All authors Madhumita Sarkar, Ben Zindorf, Bhaskar Mukherjee, Sougato Bose, Roopayan Ghosh
Mesoscale and Nanoscale Physics
Superdiffusive transport protected by topology and symmetry in all dimensions
Shaofeng Huang, Yu-Peng Wang, Jie Ren et al. (+1 more)
Superdiffusion is an anomalous transport behavior. Recently, a new mechanism, termed the “nodal mechanism," has been proposed to induce superdiffusion in
quantum models. However, existing realizations of the nodal mechanism have so far been proposed on fine-tuned, artificial
Hamiltonians, posing a significant challenge for experimental observation. In this work, we propose a broad class of models for generating superdiffusion potentially realizable in condensed matter systems across different spatial dimensions. A robust nodal structure emerges from the hybridization between the itinerant electrons and the local
impurity orbitals, protected by the intrinsic
symmetry and
topology of the electronic band. We derive a universal scaling law for the conductance, $G \sim L^{-\gamma}$, revealing how the exponent is dictated by the dimensionality of the nodal structure ($D_{\text{node}}$) and its order $n$, and the dimensionality of the system $(D)$ at high temperatures or that of the
Fermi surface ($D^F$) at low temperatures. Through numerical simulations, we validate these scaling relations at zero temperature for various models, including those based on
graphene and multi-Weyl semimetals, finding excellent agreement between our theory and the computed exponents. Beyond the scaling of conductance, our framework predicts a suite of experimentally verifiable signatures, notably a new mechanism for linear-in-temperature resistivity ($\rho \sim T$) and a divergent low-frequency optical conductivity ($\sigma(\omega) \sim \omega^{\gamma -1}$), establishing a practical route to discovering and engineering anomalous transport in
quantum materials.
Read the full abstract ▾
All authors Shaofeng Huang, Yu-Peng Wang, Jie Ren, Chen Fang
Statistical Mechanics · Cross-listed from hep-th
Mutual information as a measure of renormalizability
Brenden Bowen, Albert Farah, Spasen Chaykov et al. (+1 more)
Renormalization is an essential technique in field-theoretic descriptions of natural phenomena, where the absence of a UV-complete description yields an abundance of divergent quantities. While the renormalization prescription has been thoroughly refined for
equilibrium systems, consistently extending it to out-of-
equilibrium systems is an active area of research. In this paper, we identify a mutual information-based measure of renormalizability that applies to
quantum field theories both in and out of
equilibrium. Specifically, we use mutual information to characterize correlations between infinitesimal shells in momentum space and show that the logarithmic derivative of mutual information with mode separation, at large mode separation, is a measure of renormalizability. We first consider Minkowski spacetime, where we introduce dynamics by performing an interaction quench, initializing the field in the free theory
vacuum and then turning on the interaction. We show that the late-time mutual information relaxes to that for the interacting
vacuum and the logarithmic derivative at large mode separation is negative for super-renormalizable theories, zero for renormalizable (marginal) theories, and positive for non-renormalizable theories. We then consider a conformally-coupled scalar field on the Poincaré patch of de Sitter spacetime, initializing the field in the Bunch-Davies
vacuum in the asymptotic past. For different self-interactions and at any finite time, we find that the resulting mutual information has the same qualitative behavior as a function of mode separation, demonstrating that it can be used as a reliable indicator of renormalizability.
Read the full abstract ▾
All authors Brenden Bowen, Albert Farah, Spasen Chaykov, Nishant Agarwal
Quantum Gases · Cross-listed from quant-ph
Cooling the Sachdev-Ye-Kitaev model using thermofield double states
Thomas Schuster, Bryce Kobrin, Vincent P. Su et al. (+2 more)
We analyze a simple and efficient experimental protocol to cool the Sachdev-Ye-Kitaev (SYK) model to low temperatures. The protocol utilizes local couplings between two copies of an SYK model to create a gapped adiabatic path, between a high temperature product state and a low temperature thermofield double state. By smoothly varying the coupling strength between these two limits, one efficiently cools the SYK model. We support these predictions-and demonstrate fast cooling to the low-temperature gravitational regime-via exact numerical solutions to the large-N equations of motion that govern the ground state and dynamical properties of the coupled system. Finally, we present a theoretical framework based upon eigenstate thermalization that provides a microscopic explanation for the efficacy of the cooling protocol; intriguingly, this suggests that the protocol may be applicable for cooling strongly-interacting
quantum Hamiltonians more broadly.
Read the full abstract ▾
All authors Thomas Schuster, Bryce Kobrin, Vincent P. Su, Hugo Marrochio, Norman Y. Yao