Statistical Mechanics · Cross-listed from quant-ph
Homological Thresholds in Randomly Monitored Quantum Error-Correcting Codes
Yoshito Watanabe, Daiki Sasamoto, Bo Han et al. (+1 more)
Random projective measurements are an effective tool to model the interlinked phenomenology of monitoring, inferring, and decoding highly entangled states such as
quantum error-correcting codes. At the same time, the study of such monitored dynamics has opened a new arena for critical phenomena, renewing longstanding questions in disordered statistical mechanics, including percolation, random-bond models, and Nishimori physics. Here we investigate the robustness of stabilizer
quantum error-correcting codes under a single round of independently sampled single-
qubit Pauli measurements and demonstrate that their threshold behavior falls into two broad categories -
geometric and homological percolation transitions, with the toric code and color code being the principal examples for each class. We establish the distinct character of these two threshold theories by analyzing the logical-support criteria of these codes and by providing numerical estimates of their respective critical exponents obtained from optimized stabilizer simulations of large-scale systems with over one million
qubits. Our framework extends to non-CSS, subsystem, higher-dimensional, and Floquet stabilizer codes and allows us to determine their respective threshold phase diagrams. We exemplify how the latter provide quantitative and qualitative guidance for the computationally more demanding problems of tunable learning and maximum-likelihood decoding. As a practical application of our framework, we discuss the robustness of the gross code.
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All authors Yoshito Watanabe, Daiki Sasamoto, Bo Han, Simon Trebst
Statistical Mechanics · Cross-listed from hep-th
Entanglement Requires Fluctuations at Conformal Interfaces
Yuya Kusuki, Kosei Suzuyama and Yin Tang
We
conjecture that the universal logarithmic coefficient for capacity of
entanglement $c_{\mathrm{cap}}$ is bounded below by the corresponding
entropy coefficient $c_{\mathrm{eff}}$ at conformal interfaces. We prove the bound in free
boson and
fermion CFTs and in holographic models with interface branes, and establish it using defect perturbation theory. Numerical calculations at interacting interfaces between the tricritical Ising and Ising CFTs further support the bound. Despite this constraint, capacity provides independent interface data. We construct interfaces with identical
entropy and energy transmission coefficients but different capacity coefficients, and show that capacity can even increase as
entropy decreases.
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Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Intrinsic electromagnetic properties
Eduardo Barredo-Alamilla, Timur Z. Seidov, Daniel A. Bobylev et al. (+1 more)
Electromagnetic properties of materials are commonly inferred from how they scatter light. Here we show that this diagnostic is fundamentally incomplete. We predict the existence of an intrinsic electromagnetic property that remains invisible in any scattering experiment independently of geometry, polarization, far-field or near-field excitation. Still, this property affects the radiation emitted by the sources embedded inside the material. We reveal this phenomenon for a specially designed nonreciprocal magnetoelectric material combining
axion and dual
axion responses. Our results establish intrinsic electromagnetic properties as a distinct class of material responses and show that scattering experiments alone are insufficient to characterize matter.
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All authors Eduardo Barredo-Alamilla, Timur Z. Seidov, Daniel A. Bobylev, Maxim A. Gorlach
Disordered Systems and Neural Networks
Hyperbolic lattices with mass disorder: Phases and phase transitions
Sheersh Sen, Christopher A. Leong and Bitan Roy
Nearest-neighbor (NN) tight-binding models (TBMs) on plaquette-centered $\{ 10,3\}$ (Schläfli symbol), $\{ 8,3\}$, and $\{ 8,4\}$
hyperbolic lattices on a Poincaré disk with open boundary conditions display a vanishing, a finite, and a diverging density of states (DOS) near zero energy (band center), respectively, yielding a Dirac
liquid, a Fermi
liquid, and a flat band. Emergent bipartite nature of these
lattices within the framework of NN-TBMs, allows us to scrutinize the impact of mass disorder on the electronic states and DOS therein. From extensive numerical calculations of the average and typical DOS using the kernel
polynomial method, we show that
hyperbolic Dirac
liquid remains stable against weak mass disorder, undergoing a semimetal-to-metal
quantum phase transition at moderate disorder, followed by an Anderson metal-to-
insulator transition at even stronger disorder. The remaining two systems display only the latter transition. Critical exponents near all these transitions are found to be close to the ones mediated by on-site potential disorder.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Polynomial-time classical and quantum simulation of quantum impurity models
Jiaqing Jiang, Nathan Ju, Ojas Parekh et al. (+2 more)
Quantum impurity models are paradigmatic models of interacting
quantum matter, as well as key computational primitives for modern electronic-structure methods. They describe a small subsystem of interacting
fermions coupled to a large, noninteracting bath. We perform a comprehensive study of the computational complexity of simulating impurity models, delineating the boundary between classical and
quantum tractability for this class of problems. Our main finding is that static properties of
quantum impurity models can be calculated efficiently on a classical computer. Specifically, we give classical
algorithms that (1) estimate the ground-state energy to additive precision $\delta$ in time $\mathrm{poly}(n,\delta^{-1})$, and (2) estimate the partition function at inverse temperature $\beta$ to relative precision $\delta$ in time $\mathrm{poly}(n,\beta,\delta^{-1})$, where $n$ is the system size. These results improve the previous best-known complexity for ground-state energy estimation from quasipolynomial to
polynomial time, while establishing for the first time rigorous
polynomial-time guarantees for simulating impurity models in thermal
equilibrium. On the other hand, we find that simulating dynamical properties of impurity models is hard for classical computers but easy on a
quantum computer. As a canonical example, we show that computing their nonequilibrium Green's functions captures the full power of
quantum computation, even at finite temperature. Taken together, our results rule out superpolynomial
quantum speedups for computing static properties, but provide an avenue for
quantum advantage in simulating impurity physics out of
equilibrium.
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All authors Jiaqing Jiang, Nathan Ju, Ojas Parekh, Chaithanya Rayudu, Andrew Zhao
Disordered Systems and Neural Networks · Cross-listed from quant-ph
Beyond Light Cones: State Preparation Complexity in Quantum Spin Glasses
Omar Al-Ghattas, David Gamarnik and Bobak T Kiani
We introduce a method for studying state preparation complexity in dense
quantum $p$-
spin Hamiltonians on $n$
qubits, going beyond bounds based only on
circuit lightcones. The key input is the class's effective profile complexity, which is derived from the metric
entropy of its Pauli profiles. These profiles record expectations of all Pauli operators supported on exactly $p$
qubits. Classes with uniformly bounded quadratic effective profile complexity remain separated from the ground-state energy by a positive multiple of $\sqrt n$ for sufficiently large fixed $p$. At subquadratic effective profile complexity, the class cannot outperform a suitable
benchmark class at leading order, with product states providing a universal
benchmark. The proof combines an adaptation of a nonsymmetric
quantum de Finetti
theorem of Berta et al. (arXiv:1810.12197) with Gaussian process
entropy bounds. Applying this framework, we show that attaining near-ground-state energy requires $\Omega(n^2/\log n)$ one- and two-
qubit gates, even with arbitrary discardable ancillas. We also obtain depth-width tradeoffs,
entanglement-depth and
matrix product state bond-dimension lower bounds, and obstructions for both orientations at every fixed level of Parham's magic hierarchy (arXiv:2504.19966), with total
circuit width $O(n)$. In first-level reverse magic, a shallow
circuit is followed by an unrestricted Clifford
circuit. The latter can spread local observables across the system, preventing a direct application of small-lightcone bounds. For this first-level class, our bounds also allow arbitrarily many clean ancillas at fixed shallow-
circuit depth. A sharper
benchmark shows that Clifford+$T$
circuits with $o(n)$ $T$-gates have no leading-order energy advantage over product stabilizer states, even with unrestricted Clifford operations and arbitrary discardable ancillas.
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Statistical Mechanics · Cross-listed from quant-ph
Local random quantum circuits converge to the Porter-Thomas distribution in polynomial depth
Aniruddha Sen and Nicholas Hunter-Jones
Porter-Thomas statistics are a characteristic feature of the output distribution of random
quantum states and, more broadly, chaotic
quantum many-body systems. Convergence to Porter-Thomas plays a central role in random
circuit sampling and experimental demonstrations of
quantum advantage, where the output statistics of low-depth random
quantum circuits are expected to be approximately Porter-Thomas, despite the absence of a rigorous proof of convergence. We show that the output distribution of
polynomial-depth brickwork random
circuits converges inverse-polynomially in total variation distance to the Porter-Thomas distribution. Specifically, consider the output probability distribution over a fixed bitstring of a local random
quantum circuit, constructed from nearest-neighbor Haar random gates. Then, for any $m \geq 0$, the distribution corresponding to
circuits of depth $O(n^{2m+1}\log(n))$ is at most $O(1/n^m)$ far in total variation distance from the Porter-Thomas distribution. Our proof uses moment bounds from approximate designs, analytic estimates for characteristic functions, and a local anticoncentration property for inverse moments.
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Soft Condensed Matter · Cross-listed from physics.flu-dyn
Spiral motion enables simultaneous homogenization and enhanced transport in granular pipe flow
Wing To Ku, Patric Mueller and Thorsten Poeschel
Density waves in
gravity-driven granular pipe flow reduce transport efficiency and produce large fluctuations in the local solid fraction. Helical wall textures suppress these instabilities but at the expense of reduced throughput. Using discrete element simulations (DEM), \RefA{we find that this homogenization is associated with} spiral particle motion induced by the helical wall texture. Quantifying this motion by the mean angular velocity reveals a strong correlation between spiral motion, flow homogenization, and transport performance. Motivated by this insight, we introduce a helical pipe whose centerline follows a helical path while maintaining a constant circular cross section. This design generates stronger spiral motion than conventional helical wall textures. For suitable design parameters, the helical pipe simultaneously enhances flow homogeneity and increases the mean flow velocity beyond that of a plain straight pipe. These results support spiral motion as a useful diagnostic and design variable for simultaneously improving flow homogeneity and transport efficiency within the investigated parameter range.
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Statistical Mechanics · Cross-listed from quant-ph
Unitary Schur Sampling of Qudits via Random SWAP Tests: Hunt for Antisymmetry
Shrigyan Brahmachari, David Jakab, Henry D. Pfister et al. (+1 more)
Schur sampling is a fundamental primitive for extracting permutation-invariant information from many-body
quantum systems and has broad applications in
quantum information science.
Circuit-based implementations typically rely on coherent representation-theoretic operations such as Clebsch-Gordan transforms, generalized phase estimation, or
quantum Fourier transforms over the symmetric group. We show that
unitary Schur sampling of arbitrary permutation-invariant mixed states on $n$ $d$-dimensional qudits can instead be implemented using only pairwise SWAP tests, namely, two-qudit projective measurements onto the symmetric and antisymmetric subspaces. Our protocol achieves error $\epsilon$ in diamond distance using $O(n\min\{n,d\}^{3}\log^2(n/\epsilon))$ random SWAP tests. The central idea is to repeatedly identify and extract the largest antisymmetric subsystem. This turns
unitary Schur sampling into a search for antisymmetry and gives the
algorithm a natural interpretation as a
stochastic traversal of a Young diagram. The protocol preserves the $\mathrm{SU}(d)$-irrep state while preparing a canonical pure state in the multiplicity subsystem. As an application, we consider
quantum purity amplification (QPA), in which multiple noisy copies of a pure
quantum state are combined to produce a state of higher purity. We show that the optimal purified state can be obtained by retaining a single designated output qudit and discarding the rest.
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All authors Shrigyan Brahmachari, David Jakab, Henry D. Pfister, Iman Marvian
Strongly Correlated Electrons · Cross-listed from quant-ph
A No-Go Theorem for Order-Two Clifford Electric-Magnetic Duality
Shunta Takahashi, Zhi Li and Beni Yoshida
Electromagnetic duality in the toric code has order two at the level of anyon types and acts as a Hadamard-type logical transformation on the encoded
quantum information. Here, we ask whether it can likewise be realized microscopically as an order-two Clifford operation. For the $\mathbb{Z}_2$ toric code, we prove that any locality-preserving Clifford realization of electric-
magnetic exchange cannot have order two. Our proof is fully general and requires neither translation
symmetry with restricted families of system sizes nor a fixed pairing between vertex and plaquette stabilizers. Geometrically, the proof locally emulates the unavoidable crossing between electric and
magnetic strings, similar to a cross-cap in a non-orientable
manifold. Extending the problem to the $\mathbb{Z}_N$ toric code, we find that an order-two Clifford realization exists for odd $N$, whereas it is impossible for even $N$. Our results show that the group law of an emergent electromagnetic duality need not lift faithfully to its microscopic Clifford realization.
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Superconductivity · Cross-listed from quant-ph
Stationarity as a One-Mode Constraint on Quantum Correlation
Itai Panas
A stationary scalar correlation energy admits an exact one-mode terminal representation even when the microscopic correlated return is strongly multimode. We test predictive realizations built from specified stationary information carriers in two complementary two-electron systems with the same Coulomb repulsion but different confinement: He-like ions and harmonium (Hooke's atom). For the Coulomb sequence, canonical RHF supplies the
symmetry-faithful information carrier. The repeated same-mode return gives a He correlation error of $+0.1164$ m$E_{\mathrm h}$ and no more than $0.0157$ m$E_{\mathrm h}$ for Li$^+$–Ar$^{16+}$; H$^-$ is nevertheless bound and $93.3\%$ of its conventional correlation energy is recovered even though the RHF carrier is qualitatively strained. The dimensionless confinement factor $R_{CC}=D_{CC}/Z$ tends to $1.092394$. For harmonic confinement, an independently constructed response-compressed one-mode return gives $R_H=D_H/\sqrt{\omega}$; for $\omega\ge0.1$ it agrees with reference-inferred values within $0.21\%$ and tends to the literature high-density limit $1.309283$. Cioslowski and Pernal locate the qualitative crossover to the radially localized strongly correlated harmonium regime at $\omega_{\rm crit}\simeq0.04012$, below the quantitative domain used here. The H$^-$ endpoint and $\omega_{\rm crit}$ are therefore complementary carrier-validity boundaries: they limit the predictive realization, not exact terminal one-mode representability. A broad helium Bethe–Goldstone spectrum confirms that this terminal statement is not microscopic one-pole dynamics.
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Statistical Mechanics · Cross-listed from quant-ph
Strong Simulation of 1D Quantum Circuits via Reduced Transition Matrices
Matilde Grassi, Stefano Carignano, Luca Tagliacozzo et al. (+1 more)
Tensor networks are powerful tools for simulating
quantum many-body systems, but the growth of spatial
entanglement severely limits the direct
evolution of pure states under chaotic
unitary circuits. Here we consider a more targeted task: the approximate strong simulation of a specified output probability of a 1D chaotic brick-wall
circuit at finite relative precision. Given input and output bit strings $\by$ and $\bx$, we evaluate $p(\bx|\by)=|\bra{\bx}U(T)\ket{\by}|^2$ using the Sweeping RTM
algorithm, a transverse tensor-network contraction based on reduced transition
matrices (RTMs). The
algorithm compresses the left and right temporal boundary states jointly, seeking an output probability that converges across spatial cuts and as the bond dimension is increased. For chaotic one-dimensional brick-wall
circuits at a fixed relative target precision, we find numerical evidence that the bond dimension required to obtain stable estimates grows subexponentially over the accessible time window. Our findings open a direct route to classical probability queries for chaotic
quantum circuits, with potential applications to benchmarking and learning tasks.
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All authors Matilde Grassi, Stefano Carignano, Luca Tagliacozzo, Jacopo De Nardis
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Thin-capping layer epitaxial quantum dots for near-field quantum photonics
Yuting Guo, Jonathan Bar-David, Pasquale Cilibrizzi et al. (+3 more)
Epitaxial
quantum dots (QDs) are widely recognised as one of the best
quantum light sources, given their good stability, brightness,
quantum efficiency and coherence. To reach such properties, QDs are protected from potentially detrimental surface states by a relatively thick capping layer, typically exceeding 50nm. This prevents the implementation of near-field effects, like plasmonic-based ones, that can dramatically increase the light-matter interaction, since the control of the spontaneous emission dynamics and directionality of the emission can only occur if the emitter is in close proximity (typically tens of nanometers or less) from the metallic structures. In this work, we report the growth and optical characterisation of InAs/GaAs QDs with GaAs capping layer thickness of 10nm, 20nm, and a more standard 95nm. Remarkably, we observe emission linewidths up to 5 times smaller than previously reported, with unperturbed excitonic lifetimes. These results demonstrate that the epitaxial QD's high optical quality can be maintained even when the emitters are at reduced distances from the surface, opening the path for the exploration of near-field light-matter interactions with coherent and stable emitters, suitable for
quantum technology applications.
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All authors Yuting Guo, Jonathan Bar-David, Pasquale Cilibrizzi, Sung-Yul L. Park, Jin Dong Song, Luca Sapienza
Statistical Mechanics · Cross-listed from quant-ph
Universal Bound and Phase Transition in Many-Body Fermionic Non-Gaussianity
Masahiro Hoshino, Ryota Matsuda and Yuto Ashida
Fermionic non-Gaussianity is a resource for universal
quantum computation that can be generated by interactions in
quantum many-body systems. Using the magic Rényi
entropy (MRE) as a measure of non-Gaussianity, we derive its universal upper bound and Haar mean, proving that typical Haar-random states attain the maximal MRE density of $\ln(4/3)$ per Majorana in the large-system limit. We also show that the MRE can differ extensively between states with identical covariance
matrices. To investigate how non-Gaussianity grows toward this maximal density, we evolve a Gaussian state in imaginary and real time under the Sachdev-Ye-Kitaev
Hamiltonian. By varying the imaginary- and real-time durations, we identify a first-order transition marked by a kink in the MRE density and spontaneous breaking of the permutation
symmetry among the four copies used to evaluate the MRE. This transition represents a qualitative change in the non-Gaussianity of the state that is not reflected in the thermal free energy.
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Strongly Correlated Electrons
Magnetic Phase Diagrams and Spin Hamiltonian of Monoclinic $\alpha$-RuCl$_3$ from Angle-Dependent Torque Studies
Daniel Antoniou, Danrui Ni, John S. Pearce et al. (+3 more)
The layered honeycomb $\alpha$-RuCl$_3$ has been much explored as a candidate to display unconventional cooperative magnetism between
spin-orbit entangled $j_{\rm eff}=1/2$ Ru$^{3+}$
magnetic moments stabilized by strongly-frustrated, Kitaev and other bond-dependent anisotropic interactions. Most studies so far have focused on relatively large single
crystals that undergo a structural phase transition from monoclinic to rhombohedral upon cooling below 150 K and a
magnetic transition to zigzag order around 7 K. Here we study the magnetism of high-quality, very small (sub 100 $\mu$m diameter) single
crystals, which remain monoclinic upon cooling to low temperatures and display a sharp
magnetic transition at 14 K. Using highly-sensitive piezo-cantilever
magnetic torque measurements in fields up to 16 T, we report a comprehensive study of the
magnetic phase diagrams for
magnetic field rotated in three orthogonal crystallographic planes. Our extensive torque data collected upon varying almost continuously the angular orientation of the field as well as the field magnitude, allows clear detection of phase transitions via anomalies in the raw torque data and its higher order derivatives with respect to both angle and field magnitude. The obtained
magnetic phase diagrams show many differences compared to rhombohedral samples, displaying reduced rotational
symmetry, substantially higher fields required to suppress the spontaneous
magnetic order, and distinct field-induced phases. We provide a direct comparison of the torque data with mean-field calculations for
magnetic Hamiltonians appropriate for $\alpha$-RuCl$_3$ allowing for the monoclinic
lattice symmetry and propose minimal
magnetic structure models for all explored regions of the
magnetic phase diagrams.
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All authors Daniel Antoniou, Danrui Ni, John S. Pearce, Robert J. Cava, Amalia I. Coldea, Radu Coldea
Soft Condensed Matter
Microscopic origin of the chiral pressure in a two-dimensional fluid
Francisco Vega Reyes
We show that a two-dimensional chiral fluid supports an antisymmetric contribution to the pressure, and determine its microscopic expression. Its origin lies outside the standard kinetic and collisional channels of the normal pressure tensor, stemming instead from the average of a parity-breaking pseudo-scalar. This chiral pressure is set by the rotational (
vortex) viscosity of micropolar hydrodynamics, whose kinetic value for rough disks we compute here, to Gaussian order. Crucially, both the chiral pressure and the rotational viscosity survive at zeroth order in the gradients, meaning they persist even in the fully homogeneous fluid – which we show is not only well defined but steady (the Quiescent Chiral State, QCS). Since this averaged pseudo-scalar does not vanish in a chiral fluid, any expansion of its distribution function must contain terms in this pseudo-scalar variable.
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Strongly Correlated Electrons
Frustration-induced multiferroicity in hauerite MnS2
Vilmos Kocsis, Harish K. Singh, Kranthi K. Bestha et al. (+4 more)
Pyrite-type mineral hauerite MnS$_2$ is a
magnetic insulator with localized $S=\frac52$ moments. Below 48 K, it develops a collinear antiferromagnetic order, accompanied by unit-
cell doubling and breaking the inversion
symmetry. We demonstrate that the latter gives rise to a ferroelectric polarization of up to 360 $\mu$C/m$^2$ rendering MnS$_2$ a type-II multiferroic. Microscopically, the electronic polarization originates from S$_2$ dimers that acquire a dipole moment induced by the frustrated
magnetic ordering of neighboring Mn sites. We show that time-reversal
symmetry leaves ferroelectric domains intact, and that domain switching necessitates overcoming a high energy barrier set by the
magnetic exchange energy scale.
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All authors Vilmos Kocsis, Harish K. Singh, Kranthi K. Bestha, Yaqian Guo, Maxim Mostovoy, Jeroen van den Brink, Oleg Janson
Statistical Mechanics · Cross-listed from astro-ph.HE
Stationarity and angular momentum conservation in pulsar spin noise
Reginald Christian Bernardo
We present an analysis of
pulsar spin noise based on physically-motivated two-component models of
spin wandering. We focus on two models, distinguished by their total angular momentum dynamics: a singular, nonstationary model with a diffusive total angular momentum, and a minimal, stationary model anchored on a conserved total angular momentum. We develop scalable Gaussian process methods and, using mock data, show that the two models are fully testable and distinguishable with full-state observations, i.e., simultaneous independent data on the crust and the superfluid rotational states. This paves a path to testing stationarity in
pulsar spin noise, potentially achievable with joint continuous gravitational wave observations and
radio timing of
pulsars. However, robust inferences and predictions are harder to achieve, and depend on the priors and data quality, when only one component is observationally accessible.
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Soft Condensed Matter · Cross-listed from physics.flu-dyn
Helical pipes homogenize particle transport in pneumatic conveying
Wing To Ku, Patric Mueller and Thorsten Poeschel
Pneumatic conveying at moderate gas velocities can result in strongly heterogeneous particle transport, with slow particles accumulating near the bottom of the pipe while faster particles are transported above. Here, we investigate helical pipes as a passive means of homogenizing particle transport without increasing the gas velocity. CFD-DEM simulations show that the helical pipe induces swirling motion of the gas and particles, continuously redistributing particles across the pipe cross-section. This transforms the heterogeneous transport observed in a straight pipe into a more homogeneous state with a narrower particle-velocity distribution. The results demonstrate that helical pipes can maintain efficient pneumatic conveying at moderate gas velocities while reducing excessive particle velocities.
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Materials Science
Yuchen Lou and Alex M. Ganose
Most known inorganic
crystals exhibit symmetric atomic arrangements, yet generative models often fail to reproduce them. Explicitly enforcing these
symmetries has so far yielded fewer stable and novel structures than unconstrained generation. We introduce Generative Equivariant Orbit
Diffusion Engine (GEODE), to our knowledge the first model to combine coordinate and
lattice diffusion in Cartesian space. GEODE first samples
symmetry templates, then jointly generates the
lattice, atomic coordinates and atom types while preserving the specified
symmetry with a novel Wyckoff-constrained loss. Cartesian
diffusion gives coordinate noise a consistent physical scale that we empirically demonstrate improves performance. Unconditional generation achieves a metastable, unique and novel (mSUN) rate of 11.9%, compared with 7.7% for the next best
symmetry-aware model. We also introduce sampling time template filtering, which increases mSUN by ~6% without retraining, making GEODE competitive with leading
symmetry-agnostic models. Template selection also enables joint
symmetry and property guidance, which we demonstrate through classifier-free guidance of permittivity.
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Mesoscale and Nanoscale Physics
Symmetry considerations in chirality-induced spin selectivity
Dmitry Budker and Angela Wittmann
The chirality-induced
spin selectivity (CISS) effect, the coupling between structural chirality and electron
spin polarization, has been experimentally observed across many diverse systems. However, despite extensive theoretical effort, a unified mechanistic understanding remains elusive. In this perspective, we demonstrate how some of the basic properties of the fascinating effects of CISS can be understood based on straightforward
symmetry considerations commonly employed in fundamental particle physics. In particular, we show that CISS does not violate any fundamental
symmetries including parity and time-reversal. By anchoring CISS within the universal
language of
symmetry, we offer a robust conceptual foundation for interpreting experiments and guiding future theoretical and experimental designs.
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Statistical Mechanics · Cross-listed from hep-th
Coherent Release Fronts in Krylov Chains and Thermal AdS$_2$ Response
Mohsen Alishahiha
We study coherent release from a finite serial Krylov sector into an exact conformal tail with asymptotically linear Lanczos coefficients. We derive the cumulative occupation up to a cut that moves to greater Krylov depth with time, tracking the probability accumulated behind the propagating front. This quantity separates the release dynamics of the finite sector from subsequent propagation through the tail. The tail sets the logarithmic transit scale, while the finite sector shapes the resulting distribution. The early edge records the number of serial steps before emission, while the late edge reflects slow resonances and interference and can also exhibit logarithmic enhancements. Thus, one- and two-site sectors can share the same leading resonance in their continued-fraction descriptions yet produce distinct cumulative occupation patterns. We illustrate this framework in thermal AdS$_2$, where a dressed oscillator yields, in the weak-coupling limit, a two-site shallow sector coupled to the conformal tail.
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Statistical Mechanics · Cross-listed from quant-ph
Approximation theorems for fermionic Gaussian states
Amir-Reza Negari, Farzin Salek, Zoltán Zimborás et al. (+3 more)
A recurring principle in many-body physics is that sufficiently distributed interactions or correlations lead to an effectively mean-field description. For fermionic Gaussian states, we establish a quantitative version of this principle directly at the level of Majorana covariance
matrices. The main observation is that the admissibility condition for fermionic covariance
matrices imposes a quantitative monogamy constraint on two-point correlations: a fixed region has only a bounded covariance budget to distribute among many disjoint regions. We use this principle in three directions. First, for quadratic fermionic
Hamiltonians on finite simple graphs of high degree, we obtain product-state approximations to both the ground-state energy and the finite-temperature free energy, with error of order \(D^{-1/2}\) for \(D\)-regular graphs. Second, we prove a finite fermionic Gaussian de Finetti
theorem: a \(k\)-copy Gaussian state that is \(n\)-exchangeable under graded fermionic copy permutations is \(O(k/n)\)-close in trace norm to the product of its one-copy marginal. In particular, infinite exchangeability within the Gaussian class implies exact product structure. Third, for spatial fermionic Gaussian states with exponentially clustering mutual information, we prove that the conditional mutual information across a separating buffer decays as \(O(r^{-1})\), and hence, by recoverability, the state admits an \(O(r^{-1/2})\) trace-norm approximation by a recovered state. These results show that product and de Finetti approximations and recoverability estimates for fermionic Gaussian systems can all be derived directly from covariance-level structure.
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All authors Amir-Reza Negari, Farzin Salek, Zoltán Zimborás, Aram Harrow, Patrick Hayden, Jens Eisert
Soft Condensed Matter · Cross-listed from physics.flu-dyn
Rapid generation of relaxed centimeter-sized drops by capillary auto-ejection
Patric Mueller, Kai Ihrig, Achim Sack et al. (+2 more)
Many microgravity experiments require centimeter-sized spherical
liquid drops. In drop-tower experiments, only a few seconds of microgravity are available, so the drops must be generated and reach a nearly relaxed state within a very short time. We investigate capillary auto-ejection (puddle jumping) as a passive mechanism for producing free-floating drops and investigate how the supporting cavity can be shaped to minimize the relaxation time after ejection. For cavities with a parabolic cross-section filled with a fixed
liquid volume, minimization of the initial
liquid surface area yields a unique shape, and smoothed particle hydrodynamics simulations show that this shape also gives the shortest relaxation time within the parabolic family. Introducing a shallow central depression into the cavity reduces the relaxation time further, despite producing a larger initial
liquid surface area. These results provide design principles for capillary-driven drop generators that enable the rapid production of relaxed centimeter-sized drops during the short microgravity intervals available in drop towers.
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All authors Patric Mueller, Kai Ihrig, Achim Sack, Jonathan E. Kollmer, Thorsten Poeschel
Materials Science · Cross-listed from physics.flu-dyn
Direct Modeling of Pore Size Evolution and Microcollapse in Lyophilization by Population Balance
Isaac Stonewall Wheeler, Vivek Narsimhan, Alina A. Alexeenko et al. (+1 more)
In the primary drying step of pharmaceutical freeze drying, it is well known that amorphous excipients are prone to "microcollapse" as they approach their glass transition temperature. Existing modeling approaches for this phenomenon generally entail either avoidance of this regime or an experimentally burdensome empirical assessment of the resulting drop in resistance to mass transfer. In this work, we approach the phenomenon head-on by developing a population balance model for the pore size distribution of a freeze-dried cake during microcollapse and relating the pore size to mass transfer resistance. By treating the population balance with the method of moments and an interpolative closure, we keep the model's computational burden on par with the literature-standard model for primary drying. For a literature example when mass transfer resistance clearly varies as a function of product temperature during drying, we fit the population balance model to cases with high and low product temperature and show that it can then simulate intermediate cases with equal accuracy. The validity of the expression for mass transfer resistance is demonstrated with another literature data set, where pore size distributions were measured after the fact for a formulation without microcollapse; only a single parameter from this model needs to be fit to those cases to yield predictive accuracy in product temperature on par with post-hoc empirical assessment. Finally, a sophisticated multi-experiment fit for one formulation across a range of conditions yields quantitative agreement in product temperatures, suggesting that the rate constant for microcollapse behavior may be a material parameter and independent of the precise porous geometry.
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All authors Isaac Stonewall Wheeler, Vivek Narsimhan, Alina A. Alexeenko, Davide Fissore
Mesoscale and Nanoscale Physics
Flux- and tunnel-parity-controlled Josephson nonreciprocity from singlet-triplet competition in a parallel double quantum dot
Debika Debnath, Fernando Dominguez and Patrik Recher
Nonreciprocal supercurrents in interacting nanostructures can arise when the positive and negative critical currents probe inequivalent portions of a phase-dependent many-body spectrum. We study this mechanism in a parallel double-
quantum-dot Josephson junction with strong intradot Coulomb repulsion, where local and non-local Cooper-pair transfer coexist. Using exact diagonalization of a zero-bandwidth
Hamiltonian with explicit superconducting orbitals, we show that orbital flux and the gauge-invariant tunnel-sign parity control the interference between local Josephson processes and non-local exchange. For detuned dots, this produces flux-tunable singlet, triplet, and doublet ground-state spectral branches and two rectification regimes. Near the boundaries of the charge sector with singly occupied dots [(1,1) sector], doublet branches compete with singlet or triplet branches, yielding diode efficiencies approaching 40%. Within the triplet-dominated (1,1) sector, nearby singlet crossings asymmetrically reshape the ground-state envelope even when both critical-current extrema lie on the triplet-like branch, producing a broader response of order 10-15%. Finite temperature generally suppresses charge-crossover rectification, however, for intermediate temperatures we find an enhancement of both the normalized efficiency and the absolute critical-current asymmetry in the triplet regime. These results establish phase-dependent many-body branch competition as a gate-, flux-, and tunnel-parity-sensitive source of Josephson nonreciprocity.
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Statistical Mechanics · Cross-listed from hep-ph
Generalized fluctuation-dissipation theorem and Einstein relation in rotating equilibrium
Shuo Fang and Shi Pu
We derive a generalized fluctuation-dissipation
theorem (FDT) for vector fields in rotating thermal
equilibrium from an exact phase-space Kubo-Martin-Schwinger (KMS) relation. The resulting FDT contains rotation-induced tensorial contributions beyond a scalar thermal factor. In the local transport limit, we obtain a model-independent generalized Einstein relation with rotation in which, through second order in thermal vorticity, symmetric momentum
diffusion depends on low-frequency spectral information beyond that encoded in the rotation-dependent dissipative drag. Remarkably, we find a new Einstein-type relation linking zero modes in the spectral function to the nonrotating drag coefficient. These zero modes underlie a new mechanism for the orbital polarization of heavy quarkonium. The same FDT constraint yields a modified detailed-balance relation whose first-order vortical correction is governed by transition polarization, without explicit dependence on the bath model. Our findings establish microscopic
equilibrium constraints for studying rotating
quantum matter in various fields.
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Statistical Mechanics · Cross-listed from hep-th
DSSYK, open ASEP/TASEP and 2d dilaton gravity at strong coupling
Alexander Gorsky, Elizaveta Kovalenko and Sergei Nechaev
We discuss the triality between
stochastic growth models in the KPZ universality class, the DSSYK model, and low dimensional dilaton
gravity. The TASEP model, which will be our primary focus, is identified with the strong-coupling limit of two-dimensional
quantum gravity. The
Hamiltonian of DSSYK and the transfer
matrix of ASEP coincide up to an additive constant, and we derive the exact expression for the resolvent of the corresponding transfer
matrix in ASEP on a finite interval. We also mention the relation of cumulants with the Tutte
polynomial $T(1,q)$ of the crossing graph dual to the chord diagram, which implies the relationship of the models considered with the $Q=0$ Potts model coupled with
gravity. We further exploit the realization of all these models in terms of different versions of discrete and continuous random walks on two-dimensional
manifolds, which parameterize the
Hilbert spaces of the respective theories. The representation of TASEP as the growth model of heaps provides new insight into strong-coupling
gravity, suggesting its interpretation as an emerging phenomenon. The new dualities between ASEP and q-TASEP models and heap models providing a useful growth interpretation have been developed.
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Materials Science
Weak non-Landau-type contributions to the diamagnetism of graphite
A. V. Nikolaev, A. V. Bibikov, M. Ye. Zhuravlev et al. (+1 more)
The exceptionally large diamagnetic susceptibility of a single-
crystal graphite in the direction perpendicular to the
graphene layers is caused by the Landau levels. However, there are also other contributions to the
magnetic susceptibility. In particular, in metals the Pauli paramagnetism is leading, whereas in dielectrics the diamagnetic Langevin and paramagnetic Van Vleck terms are essential. These components of
magnetic susceptibility are also present in graphite. In this work, we calculate the magnitudes of all these small contributions from first principles. It is found that the Pauli paramagnetism is negligible (2.3 x 10^{-9} emu/g), whereas the other diamagnetic contribution - arising from the Langevin and Van Vleck mechanisms - is comparable to the in-plane experimental diamagnetism of graphite and to the diamagnetic response of C60 and C70} fullerenes. This diamagnetic contribution proves to be slightly anisotropic (-2.93 x 10^{-7} emu/g along the x- or y-axes and -2.24 x 10^{-7} emu/g along the $z-$axis), with the averaged value -2.7 x 10^{-7} emu/g.
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All authors A. V. Nikolaev, A. V. Bibikov, M. Ye. Zhuravlev, L. L. Tao
Superconductivity
Selective suppression of electronic orders via interlayer coupling in superconducting bilayer nickelate thin films
Ziao Han, Lifen Xiang, Tianren Wang et al. (+11 more)
The discovery of
spin-density-wave (SDW) order in bilayer nickelates has intensified interest in its interplay with superconductivity. Unlike cuprates, where doping rapidly suppresses the Néel temperature, the SDW transition temperature ($T_{\mathrm{SDW}}$) in bilayer nickelates is robust against oxygen annealing and even increases under pressure. Here, we combine oxygen annealing with isovalent rare-earth ($A$-site) substitution to effectively apply $c$-axis uniaxial pressure, realizing superconducting bilayer nickelate films with $T_{\mathrm{SDW}}$ suppressed from 150 K to 70 K. Notably, while SDW order is weakened but remains, a second charge-like anisotropy order is completely eliminated in the superconducting state. Polarization-resolved O $K$-edge X-ray absorption and electronic structure calculations show that strengthened interlayer coupling reconstructs the Fermi surface and weakens the SDW. These findings, consistent with a
spin-spinless stripe ground state, provide new insight into the mechanism of density wave formation and their interplay with superconductivity.
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All authors Ziao Han, Lifen Xiang, Tianren Wang, Congcong Le, Jun Zhan, Siyi Lei, Sonia Francoual, Qisi Wang, Jiangping Hu, Tao Xiang, Ronny Sutarto, Xianxin Wu, X. J. Zhou, Zhihai Zhu