Mesoscale and Nanoscale Physics
Turbulent Flows in Electron Hydrodynamics: Conductivity and Vorticity
Kanad Bhattacharya
In this article, we attempt to understand various aspects of turbulent flows in electron hydrodynamics. We analyze a rectangular channel geometry in the presence of an electric field and a Corbino geometry in the presence of a
magnetic field. In the former geometry, we analyze the conductivity of the fluid as well as the frequency spectrum of perturbations about the Poiseuille flow. While the normal Poiseuille flow has an associated conductivity which scales as $W^2$, we find a correction which scales as $W^4$ in the case of non-linear flows, where $W$ is the characteristic length of the system. In the Corbino geometry, we analyze the velocity, vorticity and
magnetic fields. We find that the vorticity can span across a wide range near the edge of the geometry, a behavior that can be reflected in the velocity and
magnetic fields.
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Strongly Correlated Electrons
Coexistence of superconductivity and excitonic pairing in a doped-biased double-layer system
V. Apinyan and M. Sahakyan
The subject of the present study is the double-layer square-
lattice system with the intralayer
phonon modulations. We investigate the superconducting and excitonic pairings, as well as their coexistence, as functions of various physical parameters in the system. These parameters include temperature, intralayer and interlayer Coulomb interactions, the electron-
phonon coupling parameter, doping and the applied electric field. The existence of superconductivity is demonstrated by considering the influence of intralayer
phonons on the total charge density leading to the modification of the total energy of the electrons. Our results provides insights into the long-standing problem of the mechanism of superconductivity in high-$T_c$ cuprate
superconductors.
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Materials Science · Cross-listed from physics.optics
Ellipsometric Identification of Transition from Layered Metal-dielectric Film to Hyperbolic Metamaterial
Samhita Kattekola, Vinod Menon, Alexander Couzis et al. (+1 more)
Hyperbolic Metamaterials (HMMs) continue to be intriguing due to their applications in super resolution imaging and spontaneous emission control. One of the successful realizations of HMMs is a layered metal-dielectric film. Despite the extensive knowledge in thin film technology and the promises of HMM's applications, the scale up and practical utilization of HMMs have not yet occurred. A general design approach is needed to predict the transition of a layered structure into an HMM. In this work, effective medium approximation and transfer
matrix method are combined to determine the transition and validated by spectroscopic ellipsometry measurements on a predefined HMM structure made of silver and alumina. Four interdependent design parameters are explored: thicknesses of metal and dielectric layers, transition wavelength, and minimum number of periods required for a layered metal-dielectric film to display
hyperbolic dispersion. The findings are presented as a practical engineering design chart, similar to a state diagram, that can be extended to other combinations of materials.
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All authors Samhita Kattekola, Vinod Menon, Alexander Couzis, Ilona Kretzschmar
Strongly Correlated Electrons
Spin-singlet dimer phase in a frustrated square lattice under a magnetic field
L. M. Ramos, M. Schmidt and F. M. Zimmer
We investigated the isotropic
spin-1/2 Heisenberg model on an anisotropic square
lattice with competing exchange interactions, motivated by the unconventional
magnetic behavior observed in the verdazyl-based compound (o-MePy-V)PF6. Using a cluster mean-field approach, we explore a field-induced phase stabilized by the interplay between frustration and
quantum fluctuations, focusing on the role of exchange interactions. We identify: (i) the formation of
spin singlet pairs, signaled by enhanced
spin-
spin correlations in specific field regimes; and (ii) a one-half magnetization plateau, emerging from a subtle balance between competing exchange couplings and field-enhanced
quantum fluctuations. Our results reveal that an enhancement of frustration, achieved by tuning small variations in the spatially anisotropic exchange interactions of the compound (o-MePy-V)PF6, can stabilize a field-induced
quantum phase where ferromagnetism coexists with
antiferromagnetic dimers. Our results provide microscopic insight into the mechanisms driving these nontrivial phases and offer theoretical support for interpreting experimental observations in this class of low-dimensional
quantum magnets.
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Materials Science · Cross-listed from physics.optics
Anisotropic Dielectric Function of Graphite Probed by Far- and Near-Field Spectroscopies
A. Toksumakov, G. Ermolaev, D. Grudinin et al. (+7 more)
Graphite is a cornerstone material for revolutionary technologies, from energy storage to the entire field of two-dimensional materials. Despite its foundational role, the predictive power required for engineering emergent optical behavior in van der Waals
heterostructures is severely constrained by persistent discrepancies in reported optical constants. We resolve this long-standing ambiguity by deploying a multi-modal approach that synergizes far-field spectroscopic ellipsometry with nanoscale near-field optical probing (s-SNOM) and micro-reflectance spectroscopy. We have established a new, self-consistent set of optical constants (n and k) for both in-plane and out-of-plane crystallographic directions across the ultraviolet-to-near-infrared spectrum. This work presents a unified set of optical constants that addresses inconsistencies in the existing literature. By establishing this definitive reference, we provide the essential foundation for the quantitative modeling and engineering of light-matter interactions in the evolving landscape of carbon-based nanophotonics.
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All authors A. Toksumakov, G. Ermolaev, D. Grudinin, A. Slavich, N. Pak, G. Tikhonowski, A. Vyshnevyy, G. Tselikov, A. Arsenin, V. Volkov
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Probing Local Topology in a Disordered Higher-Order Topological Insulator
Johannes Düreth, Simon Widmann, Philipp Gagel et al. (+13 more)
Higher-order
topology is prized for its ability to realize lower-dimensional boundary states which are stable beyond fine-tuning. However, disorder presents a failure mechanism that can destroy topological in-gap states. Here, we investigate a disordered two-dimensional polariton
lattice and employ the spectral localizer framework to define a real-space topological index rooted in crystalline spatial
symmetries. This framework enables direct real-space mapping of
topology beyond conventional momentum-space classifications, confirming the presence of corner and edge modes in this generalized Su-Schrieffer-Heeger model. Furthermore, it can directly quantify topological protection of a state. We leverage the versatility of our platform to experimentally realize normally distributed, random disorder and find that the corner states persist until the spectral gap closes. Experimentally, this corresponds to a disorder strength of approximately one quarter of the spectral gap. The spectral localizer accurately identifies the disorder strength at which the bandgap closes, establishing the framework as a predictive tool for every finite size system. Our results broaden the design principles for higher-order topological
insulators and open the way towards imple menting disorder-resilient devices for robust lasing, light-routing, and
quantum computation.
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All authors Johannes Düreth, Simon Widmann, Philipp Gagel, Siddhartha Dam, Simon Betzold, Monika Emmerling, Christian G. Mayer, David Laibacher, Martin Kamp, Oleg A. Egorov, Ulf Peschel, Tobias Hofmann, Ronny Thomale, Alexander Cerjan, Sven Höfling, Sebastian Klembt
Statistical Mechanics · Cross-listed from physics.soc-ph
Friendship-paradox paradox: Do most people's friends really have more friends than they do?
Sang Hoon Lee
The classical friendship paradox asserts that, on average, an individual's neighbors have a higher degree than the individual. This statement concerns network-level means and does not describe how often a typical node is locally dominated by its neighbors. Motivated by this distinction, we develop a framework that separates mean-based friendship paradox inequalities from two majority-type quantities: a global fraction measuring how many nodes have a degree smaller than the mean degree of their neighbors, and a local fraction based on hub centrality that measures how many nodes are dominated in a median-based sense. We show that neither fraction is constrained by the classical friendship paradox and that they can behave independently of each other. A simple example and two empirical networks illustrate how quadrant patterns in the joint distribution of a node's degree and its neighbors' degree determine the signs and magnitudes of the two fractions, and how left- or right-skewed degree distributions of neighboring nodes can yield opposite conclusions for mean-based and median-based comparisons. The resulting framework offers a clearer distinction between population averages and local majority relations and provides a foundation for future analyses of local advantage, disadvantage, and perception asymmetry in complex networks.
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Materials Science · Cross-listed from physics.chem-ph
Interaction of Polymer of Intrinsic Microporosity PIM-1 with explosive analytes at the molecular level: Combined experiment and computational modelling
Salam Mohammed, Edward B. Ogugu, Ramakant Sharma et al. (+7 more)
This work investigates the molecular-level interactions of a fluorescent microporous
polymer (PIM-1) with nitroaromatic explosives, in the context of thin film explosive sensors. Thin films of the PIM-1 were exposed to 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT), and their steady-state absorption and emission spectra measured. For comparison, the response of PIM-1 to non-explosive molecules such as benzene (BN) was also explored. Complementary electronic-structure calculations were used to predict absorption and emission spectra and to determine binding energies for the PIM-1-analyte complexes. The calculations agree well with experiment and reveal that association of nitroaromatic analyte molecules with PIM-1 alters the energy levels and the arrangements of frontier orbitals, indicating significant molecular interactions. Calculations show that the electronic properties and photo-excited electron transfer can be described by interaction with a single repeat unit of the
polymer. The molecular binding, however, involves interaction with at least three repeat units, with the DNT or TNT molecule binding into a pocket in the contorted structure of the microporous
polymer. Together, the experimental and theoretical results demonstrate that PIM-1 is a promising platform for selective nitroaromatic detection and provide molecular design principles that could improve sensitivity and selectivity in future sensor materials.
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All authors Salam Mohammed, Edward B. Ogugu, Ramakant Sharma, Dominic Taylor, Graeme Cooke, Neil McKeown, Glib Baryshnikov, Hans Ågren, Ifor D.W. Samuel, Graham A. Turnbull
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Charge reservoir as a design concept for plasmonic antennas
Rostislav Řepa, Michal Horák, Tomáš Šikola et al. (+1 more)
Plasmonic
antennas exploit localized surface plasmons to shape, confine, and enhance electromagnetic fields with subwavelength resolution. The field enhancement is contributed to by various effects, such as the inherent surface localization of plasmons or the plasmonic lightning-rod effect. Inspired by nanofocusing observed for propagating plasmons, we test the hypothesis that plasmonic
antennas with a large cross-section represent a large charge reservoir, enabling large induced charge and field enhancement. Our study reveals that a large charge reservoir is accompanied by large radiative losses, which are the dominant factor, resulting in a low field enhancement.
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All authors Rostislav Řepa, Michal Horák, Tomáš Šikola, Vlastimil Křápek
Soft Condensed Matter
Dynamical behavior of compound vesicles in wall-bounded shear flow
A. Lamura
We report a numerical study addressing the dynamics of compound vesicles confined in a channel under shear flow. The system comprises a smaller vesicle embedded within a larger one and can be used to mimic, for example, leukocytes or nucleate
cells. A two-dimensional model, which combines molecular dynamics and mesoscopic hydrodynamics including thermal fluctuations, is adopted to perform an extended investigation. We are able to vary independently the swelling degree and the relative size of vesicles, the viscosities of fluids internal and external to vesicles, and the Capillary number, so to observe a rich dynamical phenomenology which goes well beyond what observed for single vesicles, matching quantitatively with experimental findings. Tank-treading, tumbling, and trembling motions are enriched by dynamical states where inner and outer vesicles can perform different motions. We show that thermal fluctuations are crucial during trembling and swinging dynamics, as observed in experiments. Undulating motion of the external vesicle, characterized by periodic oscillation of the inclination and buckling of the membrane, is observed at high filling fractions. This latter state exhibits features that are shown to depend on the relative size, the swelling degree of both vesicles as well as on thermal noise lacking in previous analytical and numerical studies.
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Mesoscale and Nanoscale Physics
Screw-dislocation-engineered quantum dot: geometry-tunable nonlinear optics, orbital qubit addressability, and torsion metrology
Edilberto O. Silva
We study a single electron confined in a uniform-torsion medium, a continuum model of a screw dislocation density, in a perpendicular
magnetic field, and in the presence of an Aharonov–Bohm flux. Torsion alone produces radial confinement without any ad hoc potential, while the Aharonov–Bohm phase breaks the usual $m\leftrightarrow -m$
symmetry. From the exact spectrum and wave functions, we find: (i) a torsion-controlled optical transition whose energy blue-shifts from $\sim 6.8$ to $\sim 15.5$~meV and whose saturation intensity varies by an order of magnitude, enabling geometry-programmable optical switching; (ii) an Aharonov–Bohm-tunable “angular pseudospin” formed by the $m=\pm1$ states, with flux-controlled level splitting and asymmetric oscillator strengths that allow selective optical addressability; and (iii) an approximately linear torsion dependence of the transition energy that enables nanoscale torsion metrology with an estimated resolution of $\sim 10^{5}~\mathrm{m}^{-1}$. In this context, “torsion” refers to the experimentally relevant continuum limit of a uniform density of parallel screw dislocations, i.e., a
crystal with finite torsion but vanishing
curvature, which can, in practice, be engineered and probed in twisted nanowires and strained
semiconductor heterostructures. We also show how torsion provides in situ control of emitter–cavity detuning and light–matter coupling in cavity QED, in direct analogy with strain tuning of
semiconductor quantum dots in nanocavities, but here arising from a purely
geometric/topological parameter.
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Superconductivity
Effect of substrate miscut angle on critical thickness, structural and electronic properties of MBE-grown NbN films on c-plane sapphire
Anand Ithepalli, Saumya Vashishtha, Naomi Pieczulewski et al. (+7 more)
We report the structural and electronic properties of niobium nitride (NbN) thin films grown by molecular beam epitaxy on c-plane sapphire with miscut angles of $0.5^\text{o}$, $2^\text{o}$, $4^\text{o}$, and $10^\text{o}$ towards m-axis. X-ray diffraction (XRD) scans reveal that the full width at half maximum of the rocking curves around the 1 1 1 reflection of these NbN films decreases with increasing miscut. Starting from 76 arcsecs on $0.5^\text{o}$ miscut, the FWHM reduces to almost 20 arcsecs on $10^\text{o}$ miscut sapphire indicating improved structural quality. Scanning transmission electron microscopy (STEM) images indicate that NbN on c-sapphire has around 10 nm critical thickness, irrespective of the substrate miscut, above which it turns columnar. The improved structural property is correlated with a marginal increment in superconducting transition temperature $T_\text{c}$ from 12.1 K for NbN on $0.5^\text{o}$ miscut sapphire to 12.5 K for NbN on $10^\text{o}$ miscut sapphire.
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All authors Anand Ithepalli, Saumya Vashishtha, Naomi Pieczulewski, Qiao Liu, Amit Rohan Rajapurohita, Matthew Barone, Darrell Schlom, David A. Muller, Huili Grace Xing, Debdeep Jena
Strongly Correlated Electrons
Universal negative magnetoresistance in antiferromagnetic metals caused by symmetry breaking of electron wave functions
Pavel D. Grigoriev, Nikita S. Pavlov, Igor A. Nekrasov et al. (+5 more)
Layered van der Waals
crystals of topologically non-trivial and trivial semimetals with
antiferromagnetic (AFM) ordering of
magnetic sublattice are known to exhibit a negative magnetoresistance that is well correlated with AFM magnetization changes in a
magnetic field. This effect is reported in several experimental studies with EuFe2As2, EuSn2As2, EuSn2P2, etc., where the resistance decreases quadratically with field by about 5% up to the
spin-polarization field. Although this effect is well documented experimentally, its theoretical explanation is missing up to date. Here, we propose a theoretical mechanism describing the observed magnetoresistance that is inherent in AFM metals and is based on violation the binary T2
symmetry. It is almost isotropic to the field and current directions, contrary to the known mechanisms such as
giant magnetoresistance and
chiral anomaly. The proposed intrinsic mechanism of magnetoresistance is strong in a wide class of the layered AFM-ordered semimetals. The theoretically calculated magnetoresistance is qualitatively consistent with experimental data for
crystals of various composition.
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All authors Pavel D. Grigoriev, Nikita S. Pavlov, Igor A. Nekrasov, Igor R. Shein, Andrey V. Sadakov, Oleg A. Sobolevskiy, Evgeny Maltsev, Vladimir M. Pudalov
Soft Condensed Matter
Tunable dynamics of flexible magnetic microcrosses: synchronous rotation, breathing and out-of-plane arm overtaking
Joseph Tavacoli, Andris P. Stikuts, Mihir Dass et al. (+2 more)
We combine colloidal self-assembly and soft-lithography techniques to realize flexible
magnetic microcrosses that can be manipulated via external, time dependent
magnetic fields. The crosses are characterized by a central domain connected via four flexible arms. When subjected to an in-plane, rotating
magnetic field, the crosses transit from a synchronous to an asynchronous spinning motion where their average rotation decreases with the driving frequency. In the asynchronous regime and at low field amplitudes, the crosses display a breathing mode, characterized by relative oscillations between the arms, while remaining localized in the two dimensional plane. In contrast, for high field amplitudes, we observe an arm overtaking regime where two opposite filaments surpass the remaining ones forcing the cross to perform a three-dimensional gyroscopic-like rotation. Using slender body theory and balancing the effect of
magnetic and elastic interactions, we recover the experimental findings and show that the overtaking regime occurs due to different arm magnetizations. Our engineered microscopic colloidal rotors characterized by multiple flexible filaments may find potential applications for precise lab-on-a-chip operations or as stirrers dispersed within microfluidic or biological channels.
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All authors Joseph Tavacoli, Andris P. Stikuts, Mihir Dass, Tim Liedl, Pietro Tierno
Materials Science · Cross-listed from physics.class-ph
On Universal Deformations and Material Preferred Directions in Anisotropic Cauchy Elasticity
Seyedemad Motaghian and Arash Yavari
In this paper we study universal deformations in anisotropic Cauchy elasticity. We show that the universality constraints of hyperelasticity and Cauchy elasticity for transversely isotropic, orthotropic, and monoclinic solids are equivalent. This implies that for each of these
symmetry classes the universal deformations and the corresponding universal material preferred directions of hyperelastic and Cauchy elastic solids are identical. This is consistent with previous findings for isotropic solids. Universal deformations and material preferred directions are therefore independent of the existence or absence of a strain energy function.
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Strongly Correlated Electrons
Lessons from $\alpha$-RuCl3 for pursuing quantum spin liquid physics in atomically thin materials
Claudia Ojeda-Aristizabal, Xiaohu Zheng, Changsong Xu et al. (+20 more)
Quantum spin liquids can arise from Kitaev
magnetic interactions, and exhibit fractionalized excitations with the potential for a topological form of
quantum computation. This review surveys recent experimental and theoretical progress on the pursuit of phenomena related to Kitaev magnetism in layered and exfoliatable materials, which offer numerous opportunities to apply powerful techniques from the field of atomically thin materials. We primarily focus on the
antiferromagnetic Mott
insulator $\alpha$-RuCl3, which exhibits Kitaev couplings and is readily exfoliated to single- or few-layer sheets, and thus serves as a test bed for developing probes of Kitaev phenomena in atomically thin materials and devices. We introduce the Kitaev model and how it is realized in $\alpha$-RuCl3 and other material candidates; and cover $\alpha$-RuCl3 synthesis and fabrication into van der Waals
heterostructure devices. A key discovery is a work-function-mediated charge transfer that heavily dopes both the $\alpha$-RuCl3 and proximate materials, and can enhance Kitaev interactions by up to 50%. We further discuss a wide range of recent results in electronic transport and optical and tunneling spectroscopies of $\alpha$-RuCl3 devices. The experimental techniques and theoretical insights developed for $\alpha$-RuCl3 establish a framework for discovering and engineering superior two-dimensional Kitaev materials that may ultimately realize elusive
quantum spin liquid phases.
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All authors Claudia Ojeda-Aristizabal, Xiaohu Zheng, Changsong Xu, Zohar Nussinov, Yukitoshi Motome, Arnab Banerjee, Adam W. Tsen, Michael Knap, Rui-Rui Du, Gajadhar Joshi, Andy Mounce, Youngwook Kim, Benjamin M. Hunt, Dmitry Shcherbakov, Boyi Zhou, Ran Jing, Mengkun Liu, Hui Zhao, Bolin Liao, Martin Claassen, Onur Erten, Yong P. Chen, Erik A. Henriksen
Strongly Correlated Electrons
Non-invertible defects in generalized Ising models via strange correlator
Aswin Parayil Mana and Yaman Sanghavi
Defects associated with non-invertible
symmetries have attracted significant
attention in recent years. Among them, Kramers-Wannier (KW) duality defects have been investigated in both classical statistical systems and
quantum Hamiltonian models. Aasen et al. analyzed duality defects in the 2D Ising model and in statistical models built from fusion categories, while Koide et al. later constructed a duality defect in 4D
lattice gauge theory. In this work, we extend these developments by providing a systematic construction of KW duality defects/KW defects for a broad class of models formulated within the chain complex framework. Our construction employs the strange correlator, an overlap between a topologically ordered state and a product state, to realize these KW defects.
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Disordered Systems and Neural Networks · Cross-listed from physics.optics
Quantum Metamorphosis: Programmable Emergence and the Breakdown of Bulk-Edge Dichotomy in Multiscale Systems
Mahmoud Jalali Mehrabad, Alireza Parhizkar, Lida Xu et al. (+6 more)
Multiscale synergy – the interplay of a system's distinct characteristic length, time, and energy scales – is becoming a unifying thread across many contemporary branches of science. Ranging from moiré and super-moiré materials and cold atoms to DNA-templated superlattices and nested photonic networks, multiscale synergy produces behaviors not obtainable at any single scale alone. Yet a general framework that programs cross-scale interplay to steer spectra, transport, and
topology has been missing. Here, we elevate multiscale synergy from a byproduct to a general design principle for emergent phenomena. Specifically, we introduce a scale-programmable framework for hierarchically nested
lattices (HNLs) that can host
quantum metamorphosis (QuMorph) – a continuous
evolution between system-dependent features governed by a dimensionless tunable parameter $\alpha$ (the relative hopping). To exemplify, we show an HNL, in which as $\alpha$ changes, the spectrum metamorphoses from integer
quantum Hall-like to anomalous
quantum Hall-like, passing through a cocoon regime with proliferating mini-gaps. This multiscale mixing yields multiple novel phenomena, including hybrid edge-bulk states, scale-dependent
topology, topologically embedded flat bands, and isolated edge bands. We propose a feasible photonic implementation using commercially available coupled-resonator arrays, outline spatial-spectral signatures to map QuMorph, and explore applications for multi-timescale nonlinear optics. Our work establishes a scalable and programmable paradigm for engineering multiscale emergent phenomena.
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All authors Mahmoud Jalali Mehrabad, Alireza Parhizkar, Lida Xu, Gregory Moille, Avik Dutt, Dirk Englund, Kartik Srinivasan, Daniel Leykam, Mohammad Hafezi
Quantum Gases · Cross-listed from quant-ph
Realizing Unitary $k$-designs with a Single Quench
Yi-Neng Zhou, Robin Löwenberg and Julian Sonner
We present a single-quench protocol that generates
unitary $k$-designs with minimal control. A system first evolves under a random
Hamiltonian $H_1$; at a switch time $t_s \geq t_{\mathrm{Th}}$ (the Thouless time), it is quenched to an independently drawn $H_2$ from the same ensemble and then evolves under $H_2$. This single quench breaks residual spectral correlations that prevent strictly time-independent chaotic dynamics from forming higher-order designs. The resulting ensemble approaches a
unitary $k$-design using only a single control operation – far simpler than Brownian schemes with continuously randomized couplings or protocols that apply random quenches at short time intervals. Beyond offering a direct route to Haar-like randomness, the protocol yields an operational, measurement-friendly definition of $t_{\mathrm{Th}}$ and provides a quantitative diagnostic of chaoticity. It further enables
symmetry-resolved and open-system extensions,
circuit-level single-quench analogs, and immediate applications to randomized measurements, benchmarking, and
tomography.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Optimizing two-dimensional isometric tensor networks with quantum computers
Sebastian Leontica, Alberto Baiardi, Julian Schuhmacher et al. (+2 more)
We propose a hybrid
quantum-classical
algorithm for approximating the ground state of two-dimensional
quantum systems using an isometric tensor network ansatz, which maps naturally to
quantum circuits. Inspired by the density
matrix renormalization group, we optimize tensors sequentially by diagonalizing a series of effective
Hamiltonians. These are constructed using a
tomography-inspired method on a
qubit subset whose size depends only on the bond dimension. Our approach leverages
quantum computers to enable accurate solutions without relying on approximate contractions, circumventing the exponential complexity faced by classical techniques. We demonstrate our method on the two-dimensional (2D) transverse-field Ising model, achieving ground-state optimization on up to 25
qubits with modest
quantum overhead – significantly less than standard solutions based on variational
quantum eigensolvers. Overall, our results offer a path towards scalable variational
quantum algorithms in both noisy and fault-tolerant regimes.
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All authors Sebastian Leontica, Alberto Baiardi, Julian Schuhmacher, Francesco Tacchino, Ivano Tavernelli
Strongly Correlated Electrons · Cross-listed from quant-ph
Skeleton of isometric Tensor Network States for Abelian String-Net Models
Julian Boesl, Yu-Jie Liu, Frank Pollmann et al. (+1 more)
We construct parametrized isometric tensor network states – referred to as skeletons – that allow us to explore phases of abelian topological order and can be efficiently implemented on
quantum processors. We obtain stable finite correlation length deformations of string-net fixed points, which are constructed both by conserving virtual
symmetries of the tensor and by imposing local isometry constraints. They connect distinct topological phases via a shared critical point, thereby providing analytically tractable examples of phase transitions beyond anyon condensation. By mapping such classes of 2D tensor networks to 1D
stochastic automata with local update rules, we show that expectation values of generalized Pauli strings of arbitrary weight can be efficiently computed using classical methods. Therefore these skeletons not only serve as an organizing principle for abelian topological order but also provide a non-trivial testbed for
quantum processors.
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All authors Julian Boesl, Yu-Jie Liu, Frank Pollmann, Michael Knap
Strongly Correlated Electrons · Cross-listed from hep-th
Bosonisation Cohomology: Spin Structure Summation in Every Dimension
Philip Boyle Smith and Joe Davighi
Gauging
fermion parity and summing over
spin structures are subtly distinct operations. We introduce 'bosonisation
cohomology' groups $H_B^{d+2}(X)$ to capture this difference, for theories in spacetime dimension $d$ equipped with maps to some $X$. Non-trivial classes in $H_B^{d+2}(X)$ contain theories for which $(-1)^F$ is anomaly-free, but
spin structure summation is anomalous. We formulate a sequence of cobordism groups whose failure to be exact is measured by $H_B^{d+2}(X)$, and from here we compute it for $X=\text{pt}$. The result is non-trivial only in dimensions $d\in 4\mathbb{Z}+2$, being due to the presence of gravitational anomalies. The first few are $H_B^4=\mathbb{Z}_2$, probed by a theory of 8 Majorana-Weyl
fermions in $d=2$, then $H_B^8=\mathbb{Z}_8$, $H_B^{12}=\mathbb{Z}_{16}\times \mathbb{Z}_2$. We rigorously derive a general formula extending this to every spacetime dimension. Along the way, we compile many general facts about (fermionic and bosonic) anomaly
polynomials, and about
spin and pin$^-$ (co)bordism generators, that we hope might serve as a useful reference for physicists working with these objects. We briefly discuss some physics applications, including how the $H_B^{12}$ class is trivialised in supergravity. Despite the name, and notation, we make no claim that $H_B^\bullet(X)$ actually defines a
cohomology theory (in the Eilenberg-Steenrod sense).
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Materials Science · Cross-listed from physics.optics
In-Situ Growth of Halide Perovskite Single Crystals and Thin Films on Optical Fiber End Facets
Yang Yu, Kanak Kanti Bhowmik, Ruan Li et al. (+4 more)
Halide perovskites exhibit significant advantages for active optical components such as light emitting diodes,
solar cells and photodetectors due to their excellent optoelectronic properties. Their nonlinear optical effects and other characteristics also make them suitable for integration into waveguide components, such as optical fibers, for applications like optical modulation. Although some efforts have been made to integrate perovskite nanomaterials with optical fibers, technological challenges have hindered reliable in-situ preparation methods. Herein, we propose an area-selective wetting strategy for optical fibers, which utilizes hydrophobic sidewalls and hydrophilic end facets to reliably hold small precursor droplets. By introducing a space confinement strategy to suppress the kinetics of solvent evaporation, Methylammonium lead bromide (MAPbBr3) perovskite single
crystals were successfully grown in-situ on the fiber end facet. The versatility of this in-situ growth method for single
crystals on fiber end facets of various sizes has also been verified. In a separate approach, the controllable in-situ preparation of CsPbBr3 polycrystalline thin films was achieved through
vacuum-assisted rapid crystallization. Our strategy provides a controllable platform for the integration of perovskite materials and optical fibers, enabling further development in optical applications.
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All authors Yang Yu, Kanak Kanti Bhowmik, Ruan Li, Kexin Li, Lin Zhu, Hai Xiao, Lianfeng Zhao
Strongly Correlated Electrons · Cross-listed from hep-th
Generalized Global Symmetries of $T[M]$ Theories: Part II
Sergei Gukov, Po-Shen Hsin and Du Pei
We continue the investigation of
symmetries and anomalies of $T[M]$ theories obtained by compactifying 6d SCFTs on an internal
manifold $M$. We extend the notion of "polarizations on a
manifold $M$" to cases where $M$ may have boundaries or defects. Through examples with $M$ of dimension two, three, and four, we illustrate recurring themes in compactifications – for instance, the important roles played by Kaluza-Klein modes, and how the generalized
symmetries (including higher-group and non-invertible ones) of $T[M]$, together with their anomalies, arise from non-trivial combinations of the parent 6d
symmetries and the
geometric structures of the internal
manifold. For each dimension, we also focus on several topics that are especially interesting in that setting. These include: for 2-
manifolds, the geometry of the "full
moduli space" of $T[M_2]$ and its interaction with polarizations and
symmetries; for 3-
manifolds, the effect of torsion in homology on the spectrum of line operators in $T[M_3]$, together with applications to the study of
quantum invariants such as $\hat Z_a(M_3, q)$; and for 4-
manifolds, predictions for VOA$[M_4]$ following from
symmetries of $T[M_4]$, as well as the construction of a new invariant of 4-
manifolds that depends on two "$q$-parameters." Along the way, we discuss a range of topics that are of independent interest, such as how non-invertible
symmetries in higher dimensions can become invertible under compactification, how to classify defects in
quantum field theory via their response to a change of framing, and the interplay between $\hat Z_a$ and volume
conjectures.
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