Superconductivity
Interplay between charge correlations and superconductivity across the superconducting domes of CsV$_{3}$Sb$_{5-x}$Sn$_x$
Andrea N. Capa Salinas, Brenden R. Ortiz, Steven J. Gomez Alvarado et al. (+9 more)
The kagome metal CsV$_3$Sb$_5$ shows an unconventional interplay between charge density wave (CDW) order and superconductivity. Tuning the band filling is known to rapidly suppress long-range CDW order and drive the formation of two superconducting “domes" upon increasing hole concentration. Here we determine the detailed
evolution of charge correlations across this phase diagram and resolve their interplay with the superconducting state. Upon light hole-doping, the suppression of a metastable $2\times 2\times 4$ CDW state coincides with the suppression of superconducting fluctuations present in the parent CsV$_3$Sb$_5$ compound. Continued doping suppresses long-range $2\times 2\times 2$ CDW order, leaving remnant short-range, quasi-1D correlations that persist across the second superconducting dome. These higher temperature charge correlations are seemingly essential to the lower temperature superconducting state, as charge correlations vanish coincident with superconductivity as a function of hole-doping. A multidomain model of short-range V-V dimer formation within the kagome plane is proposed in the second superconducting dome, where rotational and translational
symmetry remain locally broken even in the absence of long-range CDW order.
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All authors Andrea N. Capa Salinas, Brenden R. Ortiz, Steven J. Gomez Alvarado, Sarah Schwarz, Ganesh Pokharel, Luca Buiarelli, Hyeonseo Harry Park, Shiyu Yuan, Roland Yin, Suchismita Sarker, Turan Birol, Stephen D. Wilson
Mesoscale and Nanoscale Physics · Cross-listed from physics.app-ph
Gate-controlled analog memcapacitance in LaAlO3/SrTiO3 interface-based devices
Soumen Pradhan, Victor Lopez-Richard, Igor Ricardo Filgueira e Silva et al. (+8 more)
Current memcapacitor implementations typically demand complex fabrication processes or depend on organic materials exhibiting poor environmental stability and reproducibility. Here, we demonstrate memcapacitor structures utilizing a quasi 2-dimensional electron gas, formed at the crystalline LaAlO3/SrTiO3 heterointerface, as electrodes and SiO2/SrTiO3 as dielectric layer. The observed memcapacitance originates from the charge localization in a lateral floating gate, while an applied gate voltage enables reversible tuning of the device capacitance. Furthermore, preprogrammed or erased gate biases enable controllable shifts of the capacitance hysteresis window toward positive or negative bias, leading to an enlarged capacitance gap at zero bias. A memcapacitor model developed for this system reproduces the main features of the experimental capacitance hysteresis, capturing the effects of charge fluctuations and dielectric frequency modulation within the
oxide layer. The demonstrated low-voltage operation and gate tunability of
oxide interface-based memcapacitors highlight their potential for power-efficient, capacitor-based neuromorphic and synaptic electronic architectures.
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All authors Soumen Pradhan, Victor Lopez-Richard, Igor Ricardo Filgueira e Silva, Fabian Hartmann, Ana Luiza Costa Silva, Leonardo K. Castelano, Merit Spring, Silke Kuhn, Michael Sing, Ralph Claessen, Sven Höfling
Mesoscale and Nanoscale Physics
Magnetoplasmon-Mediated Resonant Photogalvanic Effect in a Gated Strip of 2D Electrons
D.A. Rodionov, S.G. Timchenko and I.V. Zagorodnev
We theoretically investigate a nonlinear response to a linearly polarized monochromatic electromagnetic wave incident at an angle on a two-dimensional (2D) electronic system (ES) in the form of an infinite strip. The 2D ES is situated on a dielectric substrate near a perfectly conducting metal electrode (gate). The entire system is subjected to an external perpendicular constant
magnetic field. We use Maxwell's equations for electromagnetic waves, while the electrons are described within the hydrodynamic approximation using Euler's equations and neglecting electromagnetic retardation effects. The incident electromagnetic wave excites magnetoplasmons in the strip. The fully screened limit is considered when all characteristic dimensions of the system, including the plasmon wavelengths, are much larger than the distance to the gate. This limit allows the linear response to be determined fully analytically. Due to the nonlinear hydrodynamic (convective) term, the excited magnetoplasmon oscillations give rise to a DC current along the strip and a voltage across it. Surprisingly, the relationship between the photocurrent and the photovoltage in resonance is exactly the same as in the classical
Hall effect. The photovoltage is a monotonic function of the
magnetic field. However, the photocurrent exhibits a minimum, which occurs at specific wavevector directions.
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Soft Condensed Matter
Shear-induced pressure anisotropy in granular materials of nonspherical particles
Huzaif Rahim, Sudeshna Roy and Thorsten Pöschel
When a granular material composed of elongated grains is sheared in a split-bottom shear
cell, a pressure difference develops within the material. This pressure difference depends on the interparticle friction ($\mu$), which affects shear localization and particle
alignment. For large $\mu$,
alignment is confined to a narrow shear band, leading to localized increases in packing density and pressure. For small $\mu$, particles align over a wider region, leading to a nearly uniform packing density and pressure throughout the material. In contrast, spherical particles, regardless of $\mu$, maintain a uniform packing density and pressure throughout the material. We observe a phenomenological similarity to the Weissenberg effect in non-Newtonian fluids, where normal stress differences induce radial pressure gradients, unlike the uniform pressure in Newtonian fluids.
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Materials Science · Cross-listed from physics.optics
Bismuth nanogratings with narrow plasmon resonances for dynamic polarized color generation and colorimetric sensing
Fernando Chacón-Sánchez, Fátima Cabello, Marina García Pardo et al. (+3 more)
Bismuth nanostructures are appealing for sustainable color generation and sunlight harvesting, thanks to their non-toxicity and their tunable visible-to-near infrared interband plasmon resonances. However, owing to their broad and polarization-insensitive spectral features, the nanostructures reported so far displayed a limited color tunability and were lacking other functionalities such as sensing. Herein, we report bismuth nanogratings with polarization-sensitive and narrow plasmon resonances (Q > 10). They were fabricated on the $cm^2$ scale following a lithography-free approach: conformal pulsed
laser deposition of bismuth onto both the reflective and transparent nanostructured layers of DVDs. We characterized their specular reflectance for different orientations of the plane of incidence, angles of incidence, and polarizations of light. When light is polarized in the plane perpendicular to the lines, plasmon resonances occur and shift across the visible-to-near infrared upon changing the angle of incidence. In contrast, no such resonances occur when light is polarized in the plane parallel to the lines. This results in well-contrasted, polarization-sensitive colors, which are iridescent for the former orientation of polarization, and not for the latter. Resonances strongly shift upon changing the refractive index of the surrounding medium (> 500 nm/RIU), resulting in a marked change in the plasmonic color, e.g., from green in air to red in water. This showcases the potential of these nanogratings for dynamic polarized color generation and colorimetric sensing.
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All authors Fernando Chacón-Sánchez, Fátima Cabello, Marina García Pardo, Emmanuel Haro-Poniatowski, Rosalía Serna, Johann Toudert
Mesoscale and Nanoscale Physics
Quasi-one-dimensional taco-shaped bands in large-angle twisted bilayer transition metal dichalcogenides
Giovanny Espitia, Seung Hun Lee, Calvin Kaiyu Chiu et al. (+2 more)
Two-dimensional moiré materials offer a powerful, twist-tunable platform for engineering electronic bands and correlations, though most studies to date have focused on small twist angles where flat bands arise from
symmetry-pinned monolayer momenta. Here, we observe the surprising emergence of flat electronic bands with a distinctive quasi-one-dimensional dispersion at large twist angles in
bilayer transition metal dichalcogenides that originate from the $\Lambda$ valley states at generic momenta between $\Gamma$ and $K$ points. These taco-shaped anisotropic bands result from optimal interlayer hybridization between like-
spin $\Lambda$ valleys at the conduction band minimum in the Brillouin zone, resulting in directional band flattening at a magic twist-angle of 21.8$^{\circ}$. The bands form six anisotropic channels with a sixfold alternating
spin texture reminiscent of altermagnetic textures. At low energies, the density of states shows a power-law dependence due to the quasi-one-dimensional character, enhancing the potential for correlated phases. Our results provide a new platform for correlated phenomena and broaden the scope of moiré engineering to large twist angles in 2D materials.
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All authors Giovanny Espitia, Seung Hun Lee, Calvin Kaiyu Chiu, Junyeong Ahn, Mit H. Naik
Strongly Correlated Electrons
Site Preference and Possible Coexistence of Antiferromagnetic Order and Magnetic Frustration in (Co1-xMgx)10Ge3O16 (0 <= x <= 30%)
Gina Angelo, Qiang Zhang, Dylan Correll et al. (+1 more)
Geometrically frustrated magnetism has attracted tremendous
attention while chemical doping has been utilized as an important tool to probe frustrated magnetism in various systems. Here we perform a systematic study by doping non-
magnetic Mg2+ into a magnetically complicated system, Co10Ge3O16, which contains three frustrated sublattices of Co2+, e.g., triangular Co1, Kagome Co2 and Co3 sublattices. By growing
crystals for (Co1-xMgx)10Ge3O16 (0 < x <= 30%), we observed obvious site preference of Mg2+ on Co1 and Co3 sites over the Co2 site. Powder X-ray diffraction (XRD) patterns confirm the high purity of the samples and indicate systematic peak shift, consistent with the loading compositions. Although previously investigated, the
magnetic structure and expected
magnetic frustration in this system are not fully uncovered. Our temperature-dependent
magnetic susceptibility measurements suggest that the high-temperature magnetostructural phase transition with
antiferromagnetic ordering and a low-temperature broad peak are suppressed with Mg2+ doping, while two new
magnetic features emerge at high Mg2+ level. Moreover, the structural phase transition from high-temperature R-3m to low-temperature C2/m space group is absent at the
antiferromagnetic ordering temperature, as confirmed by single-
crystal XRD. By analyzing the heat capacity and
neutron powder diffraction results of the highest doped sample, (Co0.7Mg0.3)10Ge3O16, we speculate that the Co1 site is responsible for the long-range
antiferromagnetic ordering, while the other two sites are short-range correlated in addition to a Mg2+-induced
spin-glass state. This study provides more insights into the complex magnetism in Co10Ge3O16 by using the non-
magnetic Mg2+ as a probe. However, detailed
magnetic structure requires further efforts on growing large single
crystals.
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All authors Gina Angelo, Qiang Zhang, Dylan Correll, Xin Gui
Soft Condensed Matter
Heterogeneity-Induced Oscillations in Active Nematics
Alexander J. H. Houston, Michael Grinfeld, Geoff McKay et al. (+1 more)
One of the defining features of active nematics is that above a critical activity the quiescent state becomes unstable to a distorted, flowing one. We show that spatial variations in activity can fundamentally change the nature of this instability, affecting the
symmetry of the unstable mode and producing spontaneous oscillations. We analytically identify a dynamical system for the
evolution of the odd and even director modes, with the leading-order coefficients dependent on the activity profile, allowing a quantitative connection between the spatially-heterogeneous activity and dynamics, which we verify numerically. In the context of constant gradients in activity, we determine a phase diagram for the active response and highlight how variation of the activity profile causes the oscillations to vary from almost harmonic to relaxational. Our results indicate a novel route to spatio-temporal structure in active nematics and suggest experiments on controllable light-activated systems.
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All authors Alexander J. H. Houston, Michael Grinfeld, Geoff McKay, Nigel J. Mottram
Strongly Correlated Electrons · Cross-listed from quant-ph
Network-Irreducible Multiparty Entanglement in Quantum Matter
Liuke Lyu, Pedro Lauand and William Witczak-Krempa
We show that the standard approach to characterize collective
entanglement via genuine multiparty
entanglement (GME) leads to an area law in ground and thermal Gibbs states of local
Hamiltonians. To capture the truly collective part one needs to go beyond this short-range contribution tied to interfaces between subregions. Genuine network multiparty
entanglement (GNME) achieves a systematic resolution of this goal by analyzing whether a $k$-party state can be prepared by a
quantum network consisting of $(k-1)$-partite resources. We develop tools to certify and quantify GNME, and
benchmark them for GHZ, W and Dicke states. We then study the 1d transverse field Ising model, where we find a sharp peak of GNME near the critical phase transition, and rapid suppression elsewhere. Finite temperature leads to a faster death of GNME compared to GME. Furthermore, certain 2d
quantum spin liquids do not have GNME in microscopic subregions while possessing strong GME. This approach will allow to chart truly collective
entanglement in
quantum matter both in and out of
equilibrium.
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Statistical Mechanics
Space-time correlations in the 1D Directed Stochastic Sandpile model
Valentin Lallemant
Sandpile models are known to resist exact results. In this direction, space-time correlations between avalanches have proven to be especially difficult to access. One of the main obstacle to do so comes from taking
memory effects in a systematic way along the computation. In this paper, we partially fill this gap and derive recursive relations for the particle filling and avalanche 2-points correlation function in the 1D Directed
Stochastic Sandpile. These expressions allow to characterize the sign of the correlations and estimates are provided in the particle filling case. In fact, density correlations are shown to be positively correlated. This behavior is directly related to persistence of the local particle filling. On the other hand, we show that avalanches are anticorrelated in the model. This is interpreted by the fact that avalanches disrupt the system and the damage can only be fully compensated after injecting a sufficiently high number of particles. These results indicate an underlying trade off, between static and dynamic observable, for the system to sit in its stationary state. It appears that this balance is controlled by the conservation of the particle number along the avalanches.
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Other Condensed Matter · Cross-listed from quant-ph
Universal and non-universal facets of quantum critical phenomena unveiled along the Schmidt decomposition theorem
Samuel M. Soares, Lucas Squillante, Henrique S. Lima et al. (+2 more)
Critical phenomena have been extensively investigated both theoretically and experimentally in many fields, such as condensed matter physics, biology, e.g.,
brain criticality, and cosmology. In particular, the behaviour of response functions right at critical points (CPs) is highly topical. It turns out that in the frame of Boltzmann-Gibbs-von Neumann-Shannon approach, the extensive character of
entropy breaks down at CPs. The latter implies diverging susceptibilities, which is at odds with experimental observations. Here, we investigate the influence of the
spin magnitude $S$ on the
quantum Grüneisen parameter $\Gamma^{0\text{K}}_{q}$ right at CPs for the 1D Ising model under a transverse
magnetic field. Our findings are fourfold: $\textit{i}$) for higher $S$, $\Gamma^{0\text{K}}_{q}$ is increased, but remains finite, reflecting the enhancement of the
Hilbert space dimensionality; $\textit{ii}$) the Schmidt decomposition
theorem recovers the extensivity of the nonadditive $q$-
entropy $S_q$ only for a $\textit{special}$ value of the entropic index $q$; $\textit{iii}$) the universality class in the frame of $S_q$ depends only on the
symmetry of the system; $\textit{iv}$) we propose an experimental setup to explore finite-size effects in connection with the
Hilbert space occupation at CPs. Our findings unveil both universal and non-universal aspects of
quantum criticality in terms of $\Gamma^{0\text{K}}_{q}$ and $S_q$.
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All authors Samuel M. Soares, Lucas Squillante, Henrique S. Lima, Constantino Tsallis, Mariano de Souza
Materials Science
Creep Behavior of High-Entropy Alloys: A Critical Review
Mingwei Zhang, Uwe Glatzel, Martin Heilmaier et al. (+1 more)
High-
entropy alloys (HEAs) comprise a compositionally complex class of materials that in certain cases exhibit outstanding mechanical properties. While substantial progress has been made in understanding their phase stability, microstructure, and deformation mechanisms at room and cryogenic temperatures, the long-term creep behavior (>100 h) of HEAs at high temperatures (>0.6 Tm, where Tm is the melting temperature) remains relatively underexplored. This knowledge gap is critical, as many engineering applications, including those in aerospace, power generation, aero engines and
nuclear energy, require materials with good creep resistance to maintain structural integrity over extended service lifetimes. This review provides a focused and critical assessment of the current understanding of high-temperature deformation and creep behavior of HEAs, with particular
attention paid to face-centered cubic HEAs and body-centered cubic refractory HEAs. The underlying deformation mechanisms governing their creep response and the influence of phase stability at elevated temperatures are examined in detail. Recent studies reveal mechanistic differences between HEAs and conventional dilute
alloys that do not always lead to improved creep resistance belying their initial promise. Based on these findings, we discuss the challenges in designing HEAs for high-temperature structural applications and outline future research directions that may lead to creep-resistant HEAs.
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All authors Mingwei Zhang, Uwe Glatzel, Martin Heilmaier, Easo P. George
Mesoscale and Nanoscale Physics
Topological Order and Non-Hermitian Skin Effect in Generalized Ideal Chern Bands
Jiong-Hao Wang, Christopher Ekman, Raul Perea-Causin et al. (+2 more)
Fractionalization in ideal Chern bands and non-Hermitian topological physics are two active but so far separate research directions. Merging these, we generalize the notion of ideal Chern bands to the non-Hermitian realm and uncover several striking consequences both on the level of band theory and in the strongly interacting regime. Specifically, we show that the lowest band of a Kapit–Mueller
lattice model with an imaginary gauge potential satisfies a generalized ideal condition with complex Berry
curvature in sync with a complex
quantum metric. The ideal band remains purely real and exactly flat on both the
torus and cylinder: eigenstates are extended on the
torus, while on the cylinder all right and left eigenstates localize at the boundaries, yielding a non-Hermitian skin effect without spectral winding. In the interacting regime, we find that the generalized ideal condition stabilizes an incompressible
liquid at fractional fillings, retaining intrinsic non-Hermitian features on both cylinder and
torus, while strikingly distinct on different
manifolds. On the cylinder, the ground states are always skin-Laughlin states. In contrast, on the
torus, we instead observe an unconventional competition between topologically ordered Laughlin-like states and negative collective modes, arising purely from non-Hermiticity.
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All authors Jiong-Hao Wang, Christopher Ekman, Raul Perea-Causin, Hui Liu, Emil J. Bergholtz
Materials Science
A probabilistic framework for crystal structure denoising, phase classification, and order parameters
Hyuna Kwon, Babak Sadigh, Sebastien Hamel et al. (+3 more)
Atomistic simulations generate large volumes of noisy structural data, yet extracting phase labels and continuous order parameters (OPs) in a robust and general manner remains challenging. Existing tools are often specialized to a limited set of prototypes and split thermal-noise removal, phase classification, and OP construction into separate steps. Here we present a unified probabilistic framework for analyzing noisy atomic configurations with respect to known
crystal prototypes. The model predicts per-atom, per-prototype logits and aggregates them into a scalar log-probability (logP) landscape over atomic coordinates. Its gradient defines a conservative denoising field, while the logits provide local phase labels, prototype-resolved OPs, and ambiguity measures through logit margins. We train on AFLOW-mapped crystalline structures from the Materials Project with synthetic positional and elastic perturbations, then test extrapolation to stronger noise, finite-temperature disorder, point defects, water–ice coexistence, binary polymorphs, and shock-compressed Ti. A single differentiable scalar model recovers prototype identity after denoising, tracks smooth transformations such as Bain and Burgers paths, and exposes low-confidence regions near defects and phase boundaries. This provides an integrated and extensible tool for analyzing complex atomistic simulations.
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All authors Hyuna Kwon, Babak Sadigh, Sebastien Hamel, Vincenzo Lordi, John Klepeis, Fei Zhou
Superconductivity
Self-consistent inclusion of disorder in the BCS-BEC crossover near the critical temperature
M. Iskin
We develop a systematic theoretical approach to incorporate the effects of a static white-noise disorder into the BCS-BEC crossover near the critical temperature ($T_c$) of the superfluid transition. Starting from a functional-integral formulation in momentum-frequency space, we derive an effective thermodynamic potential that fully accounts for Gaussian fluctuations of the order-parameter field and its coupling to the disorder potential. The effective action, expanded to second order in both the disorder potential and the bosonic field, naturally involves third- and fourth-order terms arising from the logarithmic expansion near $T_c$. By providing a controlled description of pairing fluctuations and disorder effects, this formalism correctly recovers the well-established BCS and BEC limits. This ensures a consistent physical foundation for analyzing the entire BCS-BEC crossover, effectively anchoring the intermediate regime between these two analytically robust endpoints. The approach applies equally to continuum and
lattice systems and provides a natural framework for generalizations to multiband models.
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Strongly Correlated Electrons · Cross-listed from hep-lat
Asymptotic-freedom and massive glueballs in a qubit-regularized SU(2) gauge theory
Rui Xian Siew, Shailesh Chandrasekharan and Tanmoy Bhattacharya
We argue that a simple
qubit-regularized $\mathrm{SU}(2)$
lattice gauge theory (LGT) on a plaquette chain serves as a pseudo-one-dimensional toy model for Yang-Mills (YM) theory in three spatial dimensions. We map the chain
Hamiltonian to the Transverse Field Ising Model (TFIM) in a uniform
magnetic field and demonstrate that it can be tuned to a continuum limit in which the short-distance physics is governed by the asymptotically free Ising conformal field theory (CFT) describing free Majorana
fermions, while the long-distance regime contains massive excitations of the $E_8$
quantum field theory (QFT) that can be interpreted as one-dimensional analogues of glueballs. Furthermore, we find $\sqrt{\sigma}/m_1 = 0.249(1)$ where $\sigma$ is the string tension between two static
quarks and $m_1$ is the mass of the lightest glueball.
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Disordered Systems and Neural Networks · Cross-listed from quant-ph
Crystalline Spectral Form Factors
Dmitrii A. Trunin and David A. Huse
We investigate crystalline-like behavior of the spectral form factor in
unitary quantum systems with extremely strong
eigenvalue repulsion. Using a low-temperature Coulomb gas as a model of repulsive
eigenvalues, we derive the Debye-Waller factor suppressing periodic oscillations of the spectral form factor and estimate the order of its singularities at multiples of the Heisenberg time. We also reproduce this crystalline-like behavior using perturbed permutation
circuits and random
matrix ensembles associated with Lax
matrices. Our results lay a foundation for future studies of
quantum systems that exhibit intermediate level statistics between standard random
matrix ensembles and permutation
circuits.
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Soft Condensed Matter
Curved Odd Elasticity
Yuan Zhou, Lazaros Tsaloukidis, Jack Binysh et al. (+4 more)
Living materials such as membranes, cytoskeletal assemblies,
cell collectives and tissues can often be described as active solids—materials that are energized from within, with elastic response about a well defined reference configuration. These materials often live in complex and curved
manifolds, yet most descriptions of active solids are flat. Here, we explore the interplay between
curvature and non-reciprocal elasticity via a covariant effective theory on curved
manifolds in combination with numerical simulations. We find that
curvature spatially patterns activity, gaps the spectrum, modifies exceptional points and introduces non-Hermitian defect modes. Together these results establish a foundation for hydrodynamic and rheological models on curved
manifolds, with direct implications for living matter and active metamaterials.
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All authors Yuan Zhou, Lazaros Tsaloukidis, Jack Binysh, Yuchao Chen, Nikta Fakhri, Corentin Coulais, Piotr Surówka
Strongly Correlated Electrons · Cross-listed from hep-th
Pole skipping from universal hydrodynamics of (1+1)d QFTs
Richard A. Davison and Hanzhi Jiang
(1+1)d QFTs provide a tractable arena for understanding the emergence of hydrodynamics in thermal states. At high temperatures this process is governed by the weak breaking of conformal
symmetry, and so in this limit many features of the hydrodynamic theory that emerges have been argued to be universal. In this paper we study aspects of the stress tensor thermal two-point function in
holographic QFTs of this kind and show that they are consistent with the universal hydrodynamic theory proposed to apply at late times. Specifically, we identify the locations of the `pole skipping' points in momentum space at which there is an intersection of poles and zeroes of this two-point function in
holographic QFTs. Although these points lie outside the regime where the hydrodynamic theory is controlled, we show that their locations are consistent with those found by resumming the hydrodynamic derivative expansion near the lightcone. For example, this resummation of the universal hydrodynamics correctly predicts the butterfly velocity of
holographic theories.
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Mesoscale and Nanoscale Physics
Andreev spin qubits bound to Josephson vortices in spin-orbit coupled planar Josephson junctions
Katharina Laubscher, Valla Fatemi and Jay D. Sau
We propose a variant of Andreev
spin qubits (ASQs) defined in planar Josephson junctions based on
spin-orbit coupled two-dimensional electron gases (2DEGs) in a weak out-of-plane
magnetic field. The
magnetic field induces a linear phase gradient across the junction, generating Josephson
vortices that can host low-energy Andreev bound states (ABSs). We show that, in certain parameter regimes, the combined effect of the phase gradient and
spin-orbit coupling stabilizes an odd-
fermion parity ground state, where a single Josephson
vortex binds a spinful low-energy degree of freedom that is energetically separated from the other ABSs. This low-energy degree of freedom can be exploited to define a special type of ASQ, which we dub the
vortex spin qubit (VSQ). We show that single-
qubit gates for VSQs can be performed via flux driving, while readout can be achieved by adapting standard
circuit quantum electrodynamics (cQED) techniques developed for conventional ASQs. We further outline how an entangling two-
qubit gate can be performed using an ac current drive. We argue that VSQs offer prospects for a substantial reduction in device complexity and hardware overhead compared to conventional ASQ implementations, while preserving key advantages such as supercurrent-based readout, single-
qubit gates, and long-range two-
qubit gates.
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Mesoscale and Nanoscale Physics
Pair density wave in quarter metals from a repulsive fermionic interaction in graphene heterostructures: A renormalization group study
Sk Asrap Murshed and Bitan Roy
Electronic bands in chirally stacked $n$ layer carbon-based honeycomb
heterostructures, encompassing rhombohedral or ABC ($n \geq 3$), Bernal or AB
bilayer ($n=2$), and monolayer ($n=1$)
graphene, possess four-fold valley and
spin degeneracy. Such systems with $n \geq 2$, when subject to external perpendicular electric displacement fields, feature a fully degenerate metal at high doping, a
spin polarized but valley degenerate half-metal at moderate doping, and a non-degenerate quarter metal at low doping. Due to the fully polarized nature of the quasiparticles in the quarter metal, realized around one particular valley otherwise chosen spontaneously, it can sustain a single local superconducting ground state, representing a pair density wave that is
chiral and odd parity in nature. From a leading order renormalization group analysis, here we show that repulsive density-density interaction among such polarized fermionic excitations can foster the pair density wave phase at low temperatures. Connections with experimentally observed superconducting states in the close vicinity of the quarter metal in some members of such
graphene heterostructures family are discussed and possible routes to realize such a paired state in optical honeycomb
lattices are highlighted.
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Materials Science
Structural, physical, and Judd-Ofelt analysis of germanium magnesium-telluroborate glass containing different amounts of Tm2O3
A. A. El-Maaref, Kh. S. Shaaban and E. A. Abdel Wahab
Germanium magnesium-telluroborate glasses with the composition 78B2O3-10GeO2-5TeO2-7-x MgO-xTm2O3, x = 0, 0.25, 0.5, 1, and 1.5 mol% were fabricated by using the melt quenching process. With the increase of Tm2O3 concentration, the density values increase from 3.574 to 4.153 g/cm^3, while the molar volume values decrease from 21.145 to 19.445 cm3/mol.
Fourier transform infrared analysis supports the existence and conversion of BO3 and BO4. The conversion of BO3 to BO4 would lead to greater bridging oxygens BOs, influencing and reinforcing the glass network. The optical features were studied. The optical band gap decreased by increasing Tm2O3 content in the glass formula, while the index of refraction increased. The parameters take the values between 3.16 eV and 2.31 eV. Other optical and physical constants were determined like optical conductivity, electronegativity, metallization, reflection loss, steepness parameters, and transmission coefficient. Judd-Ofelt theory is used to estimate the optical intensities and line strengths of the present glasses. Radiative lifetimes and branching ratios are evaluated of different
manifolds belonging to Tm3+ doped present glasses. The results showed the possibility of potential applications for these materials in the fields of
laser development, Light-emitting diodes (LEDs), optical amplification and optoelectronic devices.
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Mesoscale and Nanoscale Physics
Jucheng Lin, Yicheng Zhuang, Anton M. Graf et al. (+2 more)
Bilayer graphene cavities where electrons are confined within finite
graphene flakes provide an alluring platform not only for the future nanoelectronic devices owing to the tunable energy gap but also for investigating the
quantum nature of chaos due to the trigonal warping of their
Fermi surface. Here we demonstrate that rotating the cavity boundary relative to the underlying
lattice structure drives a
quantum transition from nearly integrable dynamics to chaotic regime, observed as a concomitant crossover of
eigenvalue statistics and eigenstate profiles. Complementing the full
quantum treatment, we examine the classical backbone of this onset of chaos by employing semiclassical ray dynamics. Our results position
bilayer graphene cavities as a promising venue for investigating and engineering
quantum-chaotic behavior in
graphene-based devices.
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All authors Jucheng Lin, Yicheng Zhuang, Anton M. Graf, Eric J. Heller, Joonas Keski-Rahkonen
Strongly Correlated Electrons · Cross-listed from quant-ph
Partitioned Expansions for Approximate Tensor Network Contractions
Glen Evenbly, Johnnie Gray and Garnet Kin-Lic Chan
We propose a method for approximating the contraction of a tensor network by partitioning the network into a sum of computationally cheaper networks. This method, which we call a partitioned network expansion (PNE), builds upon recent work that systematically improves belief propagation (BP) approximations using loop corrections. However, in contrast to previous approaches, our expansion does not require a known BP fixed point to be implemented and can still yield accurate results even in cases where BP fails entirely. The flexibility of our approach is demonstrated through applications to a variety of example networks, including finite 2D and 3D networks, infinite networks, networks with open indices, and networks with degenerate BP fixed points.
Benchmark numerical results for networks composed of Ising, AKLT, and random tensors typically show an improvement in accuracy over BP by several orders of magnitude (when BP solutions are obtainable) and also demonstrate improved performance over traditional network approximations based on singular value decomposition (SVD) for certain tasks.
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Strongly Correlated Electrons
Electronic crystals and quasicrystals in semiconductor quantum wells: an AI-powered discovery
Filippo Gaggioli, Pierre-Antoine Graham and Liang Fu
The homogeneous electron gas is a cornerstone of
quantum condensed matter physics, providing the foundation for developing density functional theory and understanding electronic phases in
semiconductors. However, theoretical understanding of strongly-correlated electrons in realistic
semiconductor systems remains limited. In this work, we develop a neural network based variational approach to study
quantum wells in three dimensional geometry for a variety of electron densities and well thicknesses. Starting from first principles, our unbiased AI-powered method reveals metallic and crystalline phases with both monolayer and
bilayer charge distributions. In the emergent
bilayer, we discover a new
quantum phase of matter: the electronic quasicrystal.
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Strongly Correlated Electrons
Hybrid quantum-classical matrix-product state and Lanczos methods for electron-phonon systems with strong electronic correlations: Application to disordered systems coupled to Einstein phonons
Heiko Georg Menzler, Suman Mondal and Fabian Heidrich-Meisner
We present two
quantum-classical hybrid methods for simulating the time-dependence of electron-
phonon systems that treat electronic correlations numerically exactly and optical-
phonon degrees of freedom classically. These are a time-dependent Lanczos and a
matrix-product state method, each combined with the multi-trajectory Ehrenfest approach. Due to the approximations, reliable results are expected for the adiabatic regime of small
phonon frequencies. We discuss the convergence properties of both methods for a system of interacting spinless
fermions in one dimension and provide a
benchmark for the Holstein chain. As a first application, we study the decay of charge density wave order in a system of interacting spinless
fermions coupled to Einstein oscillators and in the presence of quenched disorder. We investigate the dependence of the relaxation dynamics on the electron-
phonon coupling strength and provide numerical evidence that the coupling of strongly disordered systems to classical oscillators leads to delocalization, thus destabilizing the (finite-size) many-body localization in this system.
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Materials Science
Disorder mediated fully compensated ferrimagnetic spin-gapless semiconducting behaviour in Cr3Al Heusler alloy
Reshna Elsa Philip, Pooja Vyas, Nikhil Joseph Joy et al. (+9 more)
Spin-gapless
semiconductors (SGSs) that simultaneously host fully compensated ferrimagnetism are highly sought for energy-efficient and stray-field-free spintronic technologies, yet their realization in chemically disordered systems has remained elusive. Here, we demonstrate that the binary Heusler
alloy Cr3Al despite adopting a fully A2-disordered structure exhibits a rare coexistence of SGS transport and a fully compensated ferrimagnetic (FCF) ground state. Single-crystalline and polycrystalline Cr3Al samples were synthesized, and comprehensive structural analyses using single
crystal XRD, synchrotron powder XRD, and
neutron powder diffraction reveal complete Cr/Al site mixing. Remarkably, this chemical disorder does not disrupt
magnetic order; instead, magnetization, X-ray
magnetic circular dichroism (XMCD), and temperature-dependent
neutron diffraction establish a robust compensated ferrimagnetic state with a vanishingly small ordered moment of 0.1(1) muB/f.u and a high Curie temperature of 773(2) K. Electrical and thermal transport measurements uncover clear SGS characteristics, including weak temperature-dependent conductivity, very low Seebeck coefficients, and electron-hole compensated transport.
Hall measurements show unusual temperature-dependent carrier concentrations consistent with disorder-modified electronic states. First-principles calculations on an A2-disordered SQS structure reproduce the experimentally observed negligibly small magnetization (0.0072 muB/f.u) and reveal a vanishing
spin-up band gap unambiguously supporting SGS behavior driven by chemical disorder. Our results identify Cr3Al as the first experimentally verified A2-disordered Heusler
alloy exhibiting both fully compensated ferrimagnetism and
spin-gapless semiconducting transport, positioning it as a robust and disorder-tolerant platform for next-generation, high-temperature spintronic devices.
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All authors Reshna Elsa Philip, Pooja Vyas, Nikhil Joseph Joy, Sandip Kumar Kuila, Sonia Beniwal, Akshata Magar, Dinesh Kumar Shukla, Partha Pratim Jana, Amit Kumar, Aftab Alam, Jayakumar Balakrishnan, Soham Manni
Mesoscale and Nanoscale Physics
Topological Engineering of a Frustrated Antiferromagnetic Triradical in Aza-Triangulene Architectures
Francisco Romero-Lara, Manuel Vilas-Varela, Manish Kumar et al. (+16 more)
Open-shell nanographenes provide a versatile platform to host unconventional
magnetic states within their {\pi}-conjugated networks. Particularly appealing are
graphene architectures that incorporate spatially separated radicals and tunable interactions, offering a scalable route toward
spin-based
quantum architectures. Triangulenes are ideal for this purpose, as their radical count scales with size, although strong hybridization prevents individual
spin control. Here, we realize a radical reconfiguration strategy that transforms a single-radical aza-triangulene into three topologically protected
spin states by covalently extending it with armchair anthene moieties of increasing length. Scanning tunnelling spectroscopy reveals emergent correlated
spins forming a frustrated
spin trimer whose interaction weakens with anthene length. This trend is captured by multi-reference electronic-structure calculations, which trace a progressive rise in polyradical character driven by the progressive reorganization of the correlated frontier orbitals into three edge-localized natural orbitals. Consequently, the initial single-radical doublet reorganizes into non-interacting edge
spins, a molecular analog of a three-
qubit quantum register.
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All authors Francisco Romero-Lara, Manuel Vilas-Varela, Manish Kumar, Ricardo Ortiz, Alessio Vegliante, Lucía Gómez-Rodrigo, Trisha Sai, Jan Patrick Calupitan, Diego Soler, Nikas Friedrich, Dongfei Wang, Jon Ortuzar, Leonard Edens, Stefano Trivini, Thomas Frederiksen, Fabian Schulz, Pavel Jelínek, Diego Peña, Jose Ignacio Pascual