Materials Science
Robust control over polar skyrmion bubble density with a combined optical and electrical approach
Lingyuan Gao and Laurent Bellaiche
Polar skyrmion bubbles are nanoscale ferroelectric domain configurations with swirling polarization textures, and often emerge in ferroelectric
oxide systems. Owing to their inhomogeneous polarization patterns, which endow them with distinct
topologies and electrical responses from homogeneous monodomains, polar skyrmion bubbles are envisaged to be promising candidates for non-volatile
memory devices. In such device, the recorded information density is directly proportional to the density of bubbles, underscoring the need for precise control over bubble nucleation. Here, using first-principles-based calculations, we demonstrate that when assisted with a DC electric field, twisted light, which has a spatially inhomogeneous field pattern, can robustly tune the density of polar skyrmion bubbles in ferroelectric ultrathin films between $10^2\sim 10^4 \rm{bit}/\mu m^2$. Moreover, by modulating DC and optical field strengths together with the beam radius, the nucleation rate, which characterizes the creation and annihilation speed of polar skyrmion bubbles, can also be well controlled. These findings highlight the unique response of ferroelectric nanofilms to optical and electric fields, which is crucial for employing polar skyrmion bubbles in the next-generation of ultrahigh-density
memory technologies.
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Strongly Correlated Electrons
Magnetic self-frustration from spontaneous structural distortion
T. Vignau Costa, G. L. Rossini, D. C. Cabra et al. (+2 more)
In frustrated magnetism,
lattice distortions mediated by magnetoelastic coupling are commonly invoked as an escape route from extensive degeneracy toward an ordered ground state and, in some cases, the onset of multiferroicity. Here we present a minimal classical model that illustrates the converse phenomenon, which we term “
magnetic self-frustration”. Monte Carlo simulations reveal that a kagomé
lattice with trivial
magnetic interactions – namely, nearest-neighbor Ising ferromagnetism – undergoes a magnetostructural transition into a breathing-like phase, characterized by irregular bond dimerization along the three kagomé directions. Structurally, the equilateral triangles belonging to one of the two kagomé sublattices spontaneously distort, expanding into isosceles triangles. An analysis to first order in the magnetoelastic coupling constant $\alpha$ shows that the shape of these triangles is remarkably robust. Acting like rigid building blocks in a puzzle, their vertices determine the geometry of the second sublattice, giving rise to contracted
ferromagnetic triangles with a variety of shapes. The
magnetic sector can be mapped onto an effective
antiferromagnetic triangular
lattice, which remains disordered down to low temperatures and retains a finite residual
entropy of one third of that of Wannier. This self-frustrated phase takes place at intermediate values of $\alpha$, separating the conventional undistorted
ferromagnetic phase at weak coupling from a strongly coupled ordered phase characterized by a regular dimerized up-up-down-down
antiferromagnetic pattern along the three kagomé directions, built from
ferromagnetic triangles and hexagons.
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All authors T. Vignau Costa, G. L. Rossini, D. C. Cabra, S. A. Grigera, R. A. Borzi
Strongly Correlated Electrons
Imaging the Magnetically Driven Reconstruction of the Electronic States in the Antiferromagnetic Topological Insulator EuSn$_2$As$_2$
Luka Khizanishvili, Erekle Jmukhadze, Anika Raisa et al. (+6 more)
The realization of the
axion insulator phase in
magnetic topological
insulators is often hindered by crystalline
symmetries that protect gapless surface states, even when time-reversal
symmetry is broken. Here, we use variable-temperature scanning tunneling microscopy (STM) and spectroscopy (STS), complemented with density functional theory (DFT), to investigate the local electronic structure of the
antiferromagnetic (AFM) topological
insulator EuSn$_2$As$_2$ across its Néel transition at $T_N = 24$ K. On the (001) surface, we observe a substantial density of intrinsic Sn vacancies that introduce nanoscale electronic inhomogeneity and p-type doping. Upon cooling below $T_N$, we resolve the emergence of two distinct magnetically driven gaps: a $\sim$100 meV gap near the
Fermi level and a $\sim$50 meV gap at the ARPES-resolved Dirac point. We attribute the former gap to AFM Brillouin-zone folding and hybridization. The characteristics of the 50 meV gap point toward the lifting of mirror-
symmetry protection by Sn vacancies and the consequent mass gapping of the Dirac point, although contributions from AFM-induced folding hybridization cannot be entirely ruled out. Our findings provide real-space evidence for strong coupling between localized moments and itinerant topological states, highlighting exfoliable EuSn$_2$As$_2$ as a potential candidate for realizing
axion-
insulator-based devices.
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All authors Luka Khizanishvili, Erekle Jmukhadze, Anika Raisa, Divyanshi Sar, Mingda Gong, Tetiana Romanova, Dariusz Kaczorowski, Wei-Cheng Lee, Pegor Aynajian
Disordered Systems and Neural Networks · Cross-listed from q-bio.NC
On the synaptic matrix eigenvalues of sparsely connected neural networks
Mohd. Gayas Ansari and Pragya Shukla
The spectral behaviour of the synaptic
matrix, representing the neuronal connection strengths, is an important tool to analyze the stability and transient dynamics of a typical
brain as well as its learning process and
memory capacity. The complexity of the
brain due to large number of
neurons as well as underlying transient mechanisms e.g. homeostasis, seizure or synaptic plasticity can lead to networks with time-varying degree and type of sparsity. This renders an exact determination of the synaptic
matrix not only technically difficult but also meaningless, leaving its statistical analysis as the best available theoretical approach. This motivates us to pursue a spectral analysis of the synaptic
matrix models with different type of sparsity and thereby analyze latter's role on various aspects of network dynamics and stability. Our results have potential relevance for detemining the type of synaptic sparsity required to induce a specific
brain function or desired transient mechanism e.g for pharmacological effects or physiological modulators.
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Materials Science
Microstructure-specific mechanisms define multistage relaxation dynamics in a metallic model-glass
Achraf Atila, Zengquan Wang, Birte Riechers et al. (+1 more)
Deciphering complex relaxation pathways in disordered solids is a central challenge across polymeric,
oxide, and metallic glasses, which traditionally relies on the interpretation of mechanical spectroscopy and resulting damping modes. Here we demonstrate the direct observation of dominant atomic-scale relaxation mechanisms during isothermal annealing of an as-quenched binary model glass towards incipient crystallization. Assessed via simulated x-ray
photon correlation spectroscopy, a multi-state structural decorrelation is uncovered via speckle-pattern analysis of the full three-dimensional diffraction sphere across the first peak of the structure factor. Over a simulation time of up to 10 $\mu$s, three distinct and subsequent decorrelation stages of thermal vibration, glassy network
evolution, and structural and chemical ordering towards crystallization are identified. These findings promote a picture where specific dynamically-separated mechanisms drive the microstructural
evolution during glass relaxation and suggest a much richer multi-mode relaxation behavior of metallic glasses than hitherto identified.
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All authors Achraf Atila, Zengquan Wang, Birte Riechers, Robert Maaß
Soft Condensed Matter
Impact of viscoelastic polymer solution droplets on a granular bed
Jooyeon Park, Theophile Meiller, Sreeram Rajesh et al. (+1 more)
The impact of
polymer solution droplets on granular beds is relevant to powder processing, binder jetting additive manufacturing, and environmental applications involving erosion control or spray deposition, yet most controlled studies of drop–grain interactions have focused on Newtonian
liquids. In this study, we experimentally investigate the impact of viscoelastic polyethylene
oxide (PEO) droplets on a dry granular bed and compare the resulting cratering dynamics with those of Newtonian
liquids over a wide range of impact energies and Ohnesorge numbers. Crater morphology changes with impact energy, and this
evolution occurs at lower energies for drops of
polymer solution, consistent with their distinct
liquid–grain interactions during impact. The crater diameter exhibits two distinct regimes: a low-energy plateau and a power-law growth at higher impact energies. We identify the transition between these regimes and show that, although the plateau size and the power law remain nearly unchanged, viscoelastic droplets reach the transition at lower impact energy than Newtonian droplets. This suggests that viscoelasticity modifies how the impact energy is partitioned between droplet deformation and dissipation in the granular bed.
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All authors Jooyeon Park, Theophile Meiller, Sreeram Rajesh, Alban Sauret
Materials Science · Cross-listed from cs.AI
Coupling Language Models with Physics-based Simulation for Synthesis of Inorganic Materials
Edward W. Staley, Tom Arbaugh, Michael Pekala et al. (+6 more)
Modern generative machine learning (ML) models can propose novel inorganic crystalline materials with targeted properties; however, synthesis planning of these materials remains difficult due to the complexity of the associated physical processes and limited availability of computational tools. We introduce a novel hybrid framework to evaluate Large
Language Models (LLMs) in inorganic synthesis planning by combining thermodynamic databases with simplified kinetics models to approximate realistic synthesis conditions. As a case study, we focus on the niobium-oxygen system, which features multiple industrially relevant
oxide phases with well-characterized data. In computational simulations, we compare LLM-generated synthesis routes with classical path-planning
algorithms, showing that the implicit priors in LLMs can yield more viable strategies. In our evaluation setting, classical search methods serve primarily as a foil rather than a direct competitor. This illustrates the relative complexity of the problem and highlights where the LLM's implicit priors add value.
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All authors Edward W. Staley, Tom Arbaugh, Michael Pekala, Alexander New, Christopher D. Stiles, Nam Q. Le, Gregory Bassen, Wyatt Bunstine, Tyrel McQueen
Mesoscale and Nanoscale Physics
Electronic screening of the friction acting on ions and water molecules in narrow carbon nanotubes
A. W. C. Lau and J. B. Sokoloff
Li, et. al., have observed a larger flow rate, resulting from osmotic pressure, of
protons and water molecules in nanometer scale diameter metallic carbon nanotubes compared to that in semiconducting carbon nanotubes. The flow rate of potassium ions, however, under an applied electric field is almost the same in metallic and semiconducting nanotubes. We propose a simple physical picture to understand these experimental results by examining the effects of screening by conduction electrons in electrically conducting carbon nanotubes on the friction experienced by
protons, water molecules, and ions flowing through the nanotube.
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Disordered Systems and Neural Networks
Localization of Active Particles on Random Arrays of Parallel Filaments
Owen Santoso and Elena Koslover
Quenched disorder in the environment can fundamentally alter transport dynamics in both active and passive systems. We explore how disordered arrays of filaments govern the distribution of intermittently moving particles which switch between diffusive and processive transport. Motivated by the mixed-polarity arrangements of parallel microtubules observed in mammalian dendrites, we show that such arrays tend to result in localization of particles at regions of convergent filament orientation. In the rapid attachment-detachment limit, the disordered system can be described by a noisy one-dimensional effective energy landscape, whose structure is approximated by a random walk. The depth and width of wells on this landscape are expressed as a function of the transport kinetics and system geometry. Localization is shown to be strongest at intermediate run-lengths, where biased transport persists long enough to sense the quenched filament polarity but not so long as to facilitate escape from local traps. These results demonstrate robust localization of particles moving on random filament networks, highlighting the emergent spatial organization that arises from an interplay of active transport and quenched disorder.
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Materials Science
Co-adsorption mechanism drives CO oxidation on defective ZnS
P.R.A. de Oliveira, C.Codeço, M.G.Menezes et al. (+3 more)
Reactivity on wide-bandgap
semiconductor surfaces relies critically on the generation of active sites. In the case of CO oxidation, however, the mere presence of defects is insufficient to drive reactivity. Here, we investigate CO oxidation on a defective ZnS single-
crystal surface by combining near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and density functional theory (DFT) calculations. NAP-XPS measurements reveal CO$_2$-like surface intermediates only under oxygen-rich conditions, consistent with oxygen-assisted CO oxidation. DFT calculations support an oxygen-assisted co-adsorption pathway in which CO interacts preferentially with adsorbed oxygen species stabilized near Zn-deficient sites, forming weakly bound CO$_2$-like structures. These results identify oxygen coverage, rather than defect density alone, as the key factor controlling CO$_2$-like intermediate formation on defective ZnS and establish defective ZnS as a model platform for studying oxygen-assisted surface chemistry on non-
oxide semiconductors.
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All authors P.R.A. de Oliveira, C.Codeço, M.G.Menezes, P.Venezuela, F.Stavale, J.A.Boscoboinik
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Geometric Instability and Self-Limitation in Driven Quantum Systems
A.M.Tishin
We develop a unified
geometric framework for local non-adiabaticity in driven
quantum systems. We show that the previously introduced AMT non adiabaticity parameter arises as a special realization of a more general
geometric instability criterion governed by the normalized Fubini Study distinguishability speed. The local
geometric evolution speed is identified as the physically relevant quantity controlling the onset of non-adiabatic instability. We introduce a universal dimensionless instability parameter measuring the competition between
quantum-state
evolution speed and spectral-gap protection. This quantity provides a local, gauge-invariant, and basis-independent criterion for arbitrary driven
Hamiltonians. Near
quantum critical points, the instability parameter diverges through inverse gap amplification, recovering the Kibble Zurek freeze-out condition directly from local
geometric data. We prove that monotonic occupation-dependent nonlinear regulators geometrically compress the
quantum metric, establishing a self-limitation
theorem in which nonlinear spectral deformation confines the accessible region of projective
Hilbert space under strong driving. The multimode extension yields a
matrix-valued instability criterion that identifies collective instability channels invisible to scalar descriptions. The framework naturally extends to open
quantum systems through the Bures metric and
quantum Fisher geometry, where thermal mixing and Lindblad decay increase the instability threshold through
geometric suppression of state distinguishability. The instability threshold further implies a universal
geometric lower bound on coherent control time and
quantum gate duration.
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Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Symmetry-Protected Quantum Computing using Metamaterials
Neil F. Johnson, Ferney J. Rodriguez and Luis Quiroga
We propose a new architecture for practical
quantum computing that combines three established principles:
symmetry protection of relative-motion
qubits via the generalized Kohn
theorem, control via twisted-light orbital angular momentum, and metamaterial nanofocusing (e.g. using Weyl-semimetal plasmonics). Crucially, the core mechanism is generic: it applies to any current or future
quantum computing system involving
parabolic confinement, including cold atoms, ions, and
semiconductor dots.
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Quantum Gases · Cross-listed from physics.atom-ph
Experimental observation of strong field stabilization
Anna R. Dardia, Spencer Walker, Yifei Bai et al. (+3 more)
Bound
quantum states such as atoms can be torn apart by strong oscillating fields. A natural expectation is that stronger fields lead to more certain destruction. In contradiction to this intuition, some theories predict a striking reversal: that as the field intensity is raised above some threshold, bound state wavefunctions can spatially bifurcate and become increasingly stable with increasing field intensity. This “strong field stabilization” was predicted decades ago in the context of atoms in pulsed
laser fields, but has resisted experimental observation due to extreme
laser intensity requirements and theoretical controversy. We report the experimental observation of strong-field stabilization of a ground state, using trapped neutral atoms to emulate the dynamics of atomic electrons in an extremely strong
laser field. We directly image the predicted wavepacket bifurcation, measure an ionization rate non-monotonic in field amplitude, and map out the regime of stabilization as a function of
laser pulse parameters. We observe that stabilization persists down to surprisingly low drive frequencies, near and below the scale of the lowest-energy excitations of the bound state. These results confirm and extend a long-standing prediction of extreme
quantum dynamics, and showcase a complementary tool for probing strong-field phenomena near and beyond the frontier of current
laser technology.
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All authors Anna R. Dardia, Spencer Walker, Yifei Bai, Petros Kousis, Alexandra S. Landsman, David M. Weld
Strongly Correlated Electrons
Electron vs. hole doping in infinite-layer nickelates: electronic structure, magnetism and correlations
Ezra Day-Roberts, Fabio Bernardini, Harrison LaBollita et al. (+3 more)
The observation of superconductivity in undoped infinite-layer nickelates $R$NiO$_2$ ($R$ = rare earth) challenges our current understanding and calls for a re-examination of the underlying electronic structure of this family of materials. In this context, it is particularly important to extend the investigation of $R$NiO$_2$ compounds from the intensively studied hole-doped regime to the almost unexplored electron-doped one. Here, we use a combination of density-functional theory and dynamical mean-field theory to study the
evolution of the electronic structure of infinite-layer nickelates in these two doping regimes. We find a striking asymmetry in the self-doping of the Ni-$d_{x^2-y^2}$ band due to the $R(5d)$ states: while this effect is strongly suppressed upon hole doping, electron doping instead leads to an increase in the size of the $R(5d)$ electron pockets, but without effectively hole-doping the Ni-$d_{x^2-y^2}$ band. This asymmetry has an important impact on the
magnetic response as antiferromagnetism is rapidly suppressed upon hole doping, whereas it remains the ground state upon electron doping. Despite these differences, electronic correlations on both sides of the phase diagram are dominated by the Ni $d_{x^2-y^2}$ orbital, suggesting that a single-band description may be appropriate for infinite-layer nickelates in both the electron- and hole-doped regimes.
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All authors Ezra Day-Roberts, Fabio Bernardini, Harrison LaBollita, Yi-Feng Zhao, Andres Cano, Antia S. Botana
Strongly Correlated Electrons
Extracting central charge from ground-state overlaps of spatially deformed Hamiltonians
Chen Bai, Xinyu Sun, Liang-Hong Mo et al. (+1 more)
We show that the conformal anomaly of a $(1+1)$-dimensional conformal field theory can be extracted directly from a ground-state wave-function overlap associated with a spatial conformal deformation. Focusing on the $q$-Möbius deformation, we derive an exact overlap formula between the deformed and undeformed ground states, whose exponent directly encodes the central charge. Motivated by this result, we construct a
lattice estimator based solely on ground-state overlaps and apply it to representative critical
quantum chains and the gapless edge modes of a two-dimensional Chern
insulator. Numerical results demonstrate that the resulting overlaps provide a simple and robust probe of the central charge in microscopic models. We further demonstrate that the deformed ground states retain universal
geometric structures in their
entanglement spectra and
entanglement entropies. These results provide a simple wave-function-based route to probing conformal data in critical systems and topological edge modes.
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All authors Chen Bai, Xinyu Sun, Liang-Hong Mo, Hong-Hao Tu
Strongly Correlated Electrons
Vestigial Nematic Order at Zero Temperature in Two-Dimensional Frustrated Quantum Antiferromagnets
Matthew C. O'Brien and Eduardo Fradkin
The phase diagram of the two-dimensional
quantum $J_1$-$J_3$ Heisenberg antiferromagnet on a square
lattice is a long-standing open problem. Despite recent advances in numerical techniques for
quantum spin models, a detailed analytical theory is still lacking. We address this problem using a semiclassical approach based on a continuum nonlinear sigma model effective field theory, applying the nonperturbative large-$N$ technique to map out the phase diagram and determine the
magnetic correlations. We show that previously-overlooked interactions are crucial for stabilizing a vestigial nematic phase, both at finite and zero temperature. Our results reveal that the spontaneous breaking of global
symmetries in the $J_1$-$J_3$ model is controlled by the strength of infrared
quantum fluctuations which are enhanced by proximity to the classical Lifshitz point.
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Quantum Gases
Aharonov-Casher Chern bands for ultracold dark state atoms
Domantas Burba, Dominykas Borodinas and Gediminas Juzeliūnas
We consider the Aharonov-Casher (AC) condition for ultracold atoms adiabatically following the dark-state in a $\Lambda$-type atom-light coupling scheme. The AC condition establishes a relation between the
geometric scalar potential and the synthetic
magnetic field, resulting in a fully degenerate lowest Landau-level-like band in the adiabatic limit even if the
magnetic field is inhomogeneous but has a proper sign. We derive a general requirement for the atom-light coupling under which the AC condition applies. The requirement holds if the Rabi frequencies of the $\Lambda$ scheme are superpositions of plane waves with the appropriate amplitudes and phases. In particular, the Rabi frequencies made of $N=3,\,4,\,6$ fine tuned plane waves yield a smooth background
magnetic field of definite sign, as well as an array of non-measurable Aharonov-Bohm flux singularities. Departing from the fine tuning, the latter singularities turn into narrow subwavelength patches of the
magnetic field with an opposite sign, which broaden the lowest energy band. The lowest band is also broadened for the fine tuned situation due to deviation from the adiabatic approach because of the finite atom-light coupling strength. It is shown that a proper combination of the two imperfections (departure from fine tuning and finite atom-light coupling strength) can lead to a significant reduction of the width of the lowest band, which can be made almost completely flat and furthermore becomes characterized by a nearly perfect geometry needed for simulating the fractional
Hall states.
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Materials Science · Cross-listed from cs.LG
AI-Guided Design and Optimization of Graphite-Based Anodes via Iterative Experimental Feedback
Qian Du, Mark M. Sullivan, James E. Saal et al. (+1 more)
This study presents an iterative AI-guided workflow that accelerates graphite-based anode development by improving both formulation feasibility and process robustness. Sequential learning via AI/ML-guided multiobjective inverse design for anode optimization was implemented using the Citrine Platform. Starting from a noisy, incomplete
dataset, the Citrine Platform was used to generate early surrogate models, which despite low predictive certainty highlighted missing process constraints. By iteratively adding feasibility labels and boundary condition failures, the workflow rapidly converged toward manufacturable, higher-performing formulations. Fabrication reliability improved from frequent process failures to 100% successful
cell production, while the fraction of
cells delivering $\geq$ 350 mAh g$^{-1}$ increased from 28.4% to 84.8%, with capacity retention rising from 42.1% to 97.3%. These results demonstrate that structured, feedback-driven AI workflows can transform imperfect industrial data into actionable guidance, enabling faster, more reproducible optimization of battery electrode manufacturing.
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All authors Qian Du, Mark M. Sullivan, James E. Saal, Florian Huber
Strongly Correlated Electrons
Photostationary Lifshitz transition in High Tc superconductor Bi2Sr2CaCu2O8+{\delta}
Ji Dai, Lukas Hellbrück, Michele Puppin et al. (+12 more)
To date, controlling the steady-state electronic band structure in high-Tc cuprate
superconductors has been achieved primarily through chemical doping or
magnetic fields. Here, we present that ultrafast optical excitation can instead drive the electronic band structure of Bi2Sr2CaCu2O8+{\delta} into a photostationary, long-lived excited state. At sufficiently high pump fluences, this state undergoes a Lifshitz transition of the
Fermi surface, characterized by a change in
topology from hole-like to electron-like. Time- and angle-resolved photoemission spectroscopy, supported by single-band tight-binding calculations, reveals that 1.6 eV photoexcitation induces band-structure evolutions closely analogous to those produced by chemical doping. These results point to an efficient photodoping mechanism involving cooperative effects, including charge transfer, renormalization of effective electronic correlations, and defect-assisted charge trapping. Our findings raise fundamental questions regarding thermalization processes occurring on timescales comparable to the
laser repetition period in cuprates. More broadly, ultrafast optical control enables access to otherwise inaccessible regions of the phase diagram by tuning the pump fluence.
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All authors Ji Dai, Lukas Hellbrück, Michele Puppin, Alberto Crepaldi, Francesco Barantani, Thomas LaGrange, Arnaud Magrez, Edoardo Martino, Neven Barisic, László Forró, J. Hugo Dil, Marco Grioni, Henrik M. Rønnow, Siham Benhabib, Fabrizio Carbone
Materials Science
Advances in electrical contacts to single crystals of emerging materials for transport measurements
Huandong Chen, Abhay N. Pasupathy and Jayakanth Ravichandran
Transport measurements that probe electrical resistivity of a material under varying external stimuli, such as temperature,
magnetic field, optical illumination, and gate voltage, are among the most important experimental techniques in condensed matter physics. These measurements provide critical insights into the fundamental electronic properties of materials. In recent years, they have facilitated the discovery and exploration of intriguing physical phenomena (e.g., superconductivity and
quantum oscillations) and unique device functionalities (e.g., photoresponse and electrostatic gating effects) in various emerging materials, particularly in the form of single
crystals. However, unlike large-scale wafers or thin films, newly synthesized single
crystals often pose substantial challenges in establishing reliable electrical contacts due to their irregular geometries, limited dimensions, inherent structural characteristics, and potential susceptibility to degradation. In this review, we highlight recent technological advancements in the fabrication of high-quality, lithographically defined multi-terminal electrodes on both exfoliable and non-exfoliable single
crystals for transport measurements. Our work provides a practical guide for researchers seeking to select appropriate contact-fabrication strategies tailored to unique characteristics of emerging
crystals.
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Mesoscale and Nanoscale Physics
Chirality routing non-polaritonic vacuum correlations in Landau polaritons
Ayoub EL-Amrani, Zakaria Mzaouali, Houssam Sabri et al. (+3 more)
Ultrastrong coupling between matter and cavity
vacuum fields can turn the electromagnetic
vacuum into a structured
quantum environment, thereby opening passive routes for modifying and manipulating material properties. Recent work has identified light–matter
entanglement as an important ingredient in these property changes, which raises the question of where the relevant
vacuum correlations actually reside. Landau polaritons provide
chiral ultrastrong coupling systems in which one circular cavity polarization forms the bright polariton branches. Here, using a
quantum information approach, we show that an exact
chiral charge in a multimode Hopfield model routes the dominant anomalous correlations, squeezing, and cavity–matter
entanglement into the opposite polarization. We find that, using parameters extracted from a multimode Landau polariton system, this hidden sector correlates the cyclotron resonance with finite momentum magnetoplasmons through Gaussian discord, while pairwise matter–matter
entanglement remains absent. We further predict a polarization anisotropy of dressed
vacuum electric field fluctuations as a signature of this
chiral routing. These results identify chirality as a
symmetry principle for organizing ultrastrong coupling
vacua and show that
quantum information tools provide a powerful framework for revealing the salient properties of Landau polaritons.
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All authors Ayoub EL-Amrani, Zakaria Mzaouali, Houssam Sabri, Herschel Rabitz, Abdelouahed El Fatimy, Dukhyung Lee
Statistical Mechanics · Cross-listed from hep-th
Phase separation seeded by Z2 and U(1) topological defects from holography
Zi-Qiang Zhao, Zhang-Yu Nie, Jing-Fei Zhang et al. (+1 more)
We study the interaction between spontaneous
symmetry breaking and phase separation dynamics in holography. Using a double-quench protocol, the system first rapidly crosses the critical point and generates topological defects, while a second quench drives the system into a nonlinear unstable regime with spinodal decomposition. We investigate both $\mathbb{Z}_2$ and $U(1)$ symmetric systems, where different types of topological defects emerge during
symmetry breaking. We show that topological defects dynamically determine the nucleation sites of phase separation. As the instability grows, the defect cores expand into macroscopic phase-separated domains. Despite the distinct
symmetries and topological properties of these defects, both systems exhibit the same universal dynamical behavior, indicating that topological defects can universally serve as dynamical seeds for subsequent phase separation.
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All authors Zi-Qiang Zhao, Zhang-Yu Nie, Jing-Fei Zhang, Xin Zhang
Statistical Mechanics · Cross-listed from nlin.AO
Decomposition of Anomalous Diffusion in two-state random walks
Abhijit Bera and Kevin. E. Bassler
Two-state
stochastic models, where motion alternates between distinct dynamical modes, are widely observed in complex systems. Here we study the Two-State Random Walk (TSRW), which switches between a continuous-time random walk (CTRW) rest state and a standard L'evy walk (LW) motion state, each with power-law distributed sojourn times. Using anomalous
diffusion decomposition, we show that TSRWs exhibit a generic coexistence of Joseph (correlation), Noah (heavy-tailed increments), and Moses (aging) effects. Strikingly, although classical L'evy walks alone possess only the Joseph effect, both Noah and Moses effects emerge in TSRWs solely due to
stochastic switching with the CTRW phase. Our results demonstrate that coupling between dynamical states can fundamentally reshape the mechanisms driving anomalous
diffusion, offering a minimal yet powerful framework for transport in heterogeneous and intermittently switching environments.
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Strongly Correlated Electrons
Twin Algebras: Condensable Algebras beyond Anyons
Yuhan Gai, Sakura Schafer-Nameki and Alison Warman
Condensable
algebras in 2+1d non-
chiral topological orders characterize gapped boundary conditions and interfaces. Applied to the
Symmetry Topological Field Theory, they allow classification of symmetric gapped phases and impose sharp constraints on possible phase transitions. A condensable
algebra is specified not only by its underlying set of anyons, which end on the boundary or interface, but also by its
algebra structure. We introduce the concept of twin condensable
algebras, which have the same anyon decomposition, but inequivalent
algebra structure. We revisit the classification of condensable
algebras in $\mathcal{Z}(\text{Vec}_G^\omega)$, i.e. in group-theoretical topological orders for finite groups $G$ with anomaly $\omega$. In this context we are able to identify twin
algebras that arise from different mechanisms, such as subgroup data, SPT cocycles, and
symmetry actions. In particular, we construct infinite families of examples of twins from so-called Gassmann triples, and exhibit cases in which the reduced topological orders are inequivalent despite having identical anyon content. Physically, twin
algebras describe distinct symmetric phases that have isomorphic spaces of ground states, but inequivalent order parameters. Such twin phases never exhibit relative spontaneous
symmetry breaking, and can be used to construct phase transitions without hidden
symmetry breaking, which are intrinsically beyond Landau transitions.
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Strongly Correlated Electrons
Twin Phases: Intrinsic Deconfined Quantum Criticality
Alison Warman, Yuhan Gai and Sakura Schafer-Nameki
We introduce the concept of twin phases for a
symmetry $\mathcal{S}$, defined as inequivalent phases, whose order parameters are part of the same generalized charge under $\mathcal{S}$. Stable, direct transitions between such twin phases are never spontaneous-
symmetry-breaking transitions, even after (partially) gauging the initial
symmetry $\mathcal{S}$: they are phase transitions without hidden
symmetry breaking. We illustrate this with an (anomalous) finite group
symmetry in 1+1d, which exhibits such intrinsically beyond Landau transition, i.e. an intrinsically Deconfined
Quantum Critical Point (DQCP).
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Quantum Gases
Floquet Engineering of Quantum Transport through two Driven Impurities
Vincenzo Bruno, Corinna Kollath, Roberta Citro et al. (+1 more)
Floquet engineering offers powerful tools to manipulate
quantum states by periodically driving physical parameters. In this work, we investigate the
quantum transport through two periodically driven
impurities in a mesoscopic one-dimensional channel. By mapping the time-dependent
Hamiltonian into an effective multichannel scattering problem, we unveil a rich landscape of transport phenomena arising from the interplay between Fabry-Perot cavity modes and Fano interference. We demonstrate that the inter-
impurity distance acts as a critical control parameter, allowing for the formation of Bound States in the Continuum (BICs). Furthermore, we identify Quasi-BICs, extremely narrow resonances with finite lifetimes, that can be dynamically tuned by the drive amplitude. We show that these states enable a robust coherent trapping mechanism, allowing the system to switch from perfect transparency or reflection to strong localization with
giant Wigner time delays. Our results suggest possible applications for tunable delay lines and
quantum memories, with feasible experimental realizations in the context of cold atoms.
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All authors Vincenzo Bruno, Corinna Kollath, Roberta Citro, Ameneh Sheikhan
Strongly Correlated Electrons · Cross-listed from physics.chem-ph
Richardson-Gaudin states of non-zero seniority III: The Perfect-Pairing limit
Paul A. Johnson
Strongly correlated electrons can be treated with a configuration interaction of Slater determinants grouped by number of unpaired electrons with exponential cost. The first two papers in this series demonstrated that single reference methods built from Richardson-Gaudin states gave results of similar quality at
polynomial cost. In this contribution, the states are simplified substantially yielding the perfect-pairing state as a reference along with its low-lying excitations. The states are much simpler, the computational cost is substantially reduced, and there is no sacrifice in numerical accuracy. Second-order Epstein-Nesbet perturbative corrections for the valence electrons are similar in quality to the complete active space self-consistent field.
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Materials Science · Cross-listed from cs.CE
Can dents and gouges compromise the structural integrity of hydrogen transport pipelines?
R. Das, B. Bezensek and E. Martínez-Pañeda
Repurposing natural gas pipelines for hydrogen transport requires understanding how external defects, like dents and gouges, affect structural integrity under H$_2$ exposure. To address this, we combine experiments with a new hydrogen embrittlement model aimed at large plastic straining scenarios, which integrates: (i) multi-trap hydrogen transport, (ii) finite-strain plasticity, and (iii) a hydrogen- and triaxiality-dependent damage law. Each constituent of the model is validated with experiments on X65 pipeline steel: (i) hydrogen permeation, (ii) full-scale pipe-indentation, and (iii) mechanical testing at different hydrogen and triaxiality levels. The validated model is used to study passive (indent before H$_2$ exposure) and active (indent with H$_2$) dents and gouges. Results reveal that hydrogen does not significantly increase the damage severity of those defects, unless hydrogen egress is completely precluded at the outer surface of a pipeline that is being pressurised internally and contains a pre-existing passive dent with a gouge.
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Soft Condensed Matter
Recovering the Shape of a Contact Line
Ashbell Abraham, Audrey Profeta, Jeanette Smit et al. (+7 more)
We study the conditions for a three-phase contact line to return to a previous position. We drive a water-air-glass contact line between two horizontal plates, by slowly adding and removing water with a constant volume amplitude. For the first several cycles, the contact line ends each cycle with a different shape, in contrast with previously published work. Eventually the shapes begin to repeat, and the system has
memory: a cycle with a smaller amplitude ends in a different shape, but even one cycle at the original amplitude recovers the steady-state shape. After a cycle at a larger amplitude, the steady-state shape is erased. We find that our tight control of the enclosed volume creates a global interaction, wherein only the least stable part of the contact line can move. Using theory and minimal models, we show that this interaction gives rise to the transient behaviors. Our study sheds light on the origins of reversibility and
memory in a system where neither is guaranteed, and shows that the physics of contact line motion changes in a confined environment.
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All authors Ashbell Abraham, Audrey Profeta, Jeanette Smit, Esmeralda Orozco, Charity Lizardo, Dani Medina, Aidan McGuckin, Bri Kroger, Shae Cole, Nathan C.Keim
Strongly Correlated Electrons
Migdal-Eliashberg and SUS-$Y^2$-SYK
D. V. Khveshchenko
This note addresses a number of subtle issues pertaining to the long-standing problem of strong
phonon-like
fermion-
boson coupling. Among the central topics are the customary Migdal-Eliashberg approximation in the pertinent Schwinger-Dyson gap equation and its solutions. The previously gained insight is assessed by contrasting it against the various (non-)supersymmetric variants of the Yukawa-Sachdev-Ye-Kitaev model. Also, some previously discussed (pseudo-)
holographic aspects of
fermion pairing in such models are commented upon.
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