Strongly Correlated Electrons
Ultrafast electron crystallography reveals the atomic pathway of a light-driven correlated insulator-to-metal transition
Arthur Niedermayr, Hongyi Xu, Chin Shen Ong et al. (+9 more)
Ultrafast phase transitions in correlated materials are often inferred from selected diffraction peak intensities or diffraction peak displacements, leaving the underlying three-dimensional atomic trajectories elusive. Resolving these trajectories is essential for identifying which atomic motions drive changes in electronic properties and how they couple to electronic degrees of freedom. We address this challenge in vanadium dioxide (VO2), a correlated oxide with a near-room-temperature transition between the insulating monoclinic (M1) phase and metallic rutile (R) phase. For this purpose, we introduce ultrafast three-dimensional electron diffraction, which enables refinement of the transient unit
cell and internal V and O coordinates, revealing the V-V dimerization and zigzag motion during the phase transition. The refined atomic coordinates follow a linear trajectory in real space during the transition, in contrast to nonlinear or sequential transformation pathways inferred from more indirect observables in earlier work.
Quantum many-body calculations treating each V-V pair as a correlated unit show that dimerization creates the level splitting responsible for the electronic gap, which is further enhanced by nonlocal electronic interactions between the paired V atoms. The gap collapses when dimerization is lost. This work turns time-resolved diffraction from order-parameter tracking into transient crystallography, directly connecting atomic trajectories to electronic mechanisms in correlated materials.
Read the full abstract ▾
All authors Arthur Niedermayr, Hongyi Xu, Chin Shen Ong, Patrik Thunström, Michael Yannai, Jianyu Wu, Gaolong Cao, Lior Kornblum, Ido Kaminer, Oscar Grånäs, Xiaodong Zou, Jonas Weissenrieder
Strongly Correlated Electrons
Deviation from Fermi-liquid $T^2$ resistivity caused by collective transport
Kamran Behnia
`Fermi-
liquid behavior' is nowadays used as a shorthand for quadratic temperature dependence of the electrical resistivity. In a metal, for this to occur, electrons must be cooled well below the Fermi degeneracy temperature, $T_{\mathrm{F}}$. A departure from this behavior is observed at finite temperature. Here, we note that this departure has opposite signs in two distinct types of Fermi
liquids. In weakly correlated ones, the upward departure implies a higher exponent of the inelastic resistivity, attributable to additional scattering by
phonons. In contrast, there is a downward deviation in strongly correlated metals, which implies either reduced scattering or additional conduction, as in the case of normal
liquid $^3$He, in which a distinct contribution to heat transport by a sound mode has been recently identified. Such a channel of conduction smoothly transforms across $T_{\mathrm{F}}$ to the one captured by the Bridgman formula for thermal conductivity of classical
liquids. In three metals (UPt$_3$, Sr$_2$RuO$_4$, and heavily overdoped LSCO), according to the available experimental data, the normalized amplitude of excess conductivity at $T/T_{\mathrm{F}}\simeq0.02$ is comparable to what has been seen in $^3$He, suggesting, without establishing, a common origin.
Read the full abstract ▾
Materials Science
Plasmon drag and photoinduced magnetic effects in plasmonic and magnetic metals
Md Afzalur Rab, Terence Baker and Natalia Noginova
Photoinduced electric effects in plasmonic and
magnetic materials under pulsed
laser illumination exceed the prediction of the electromagnetic momentum-transfer mechanism by orders of magnitude. In order to get more information on the nature of the effect we study the kinetics of photovoltages in permalloy thin films at different photoexcitation configurations. The photoinduced electric signals consist of magnetically dependent and magnetically independent components which are of significant magnitude and mainly follow the temporal profile of the
laser pulse. In contrast, the predicted contribution from the Anomalous Nernst Effect is much weaker and exhibits substantially slower kinetics. These observations suggest that ultrafast photoexcited hot electrons, rather than thermal mechanisms, play the dominant role in generating the observed photovoltage.
Read the full abstract ▾
Materials Science
FP-DeErr: Application-Oriented Error Decomposition for Foundation Potentials
Kiyan Amirian, Ramanuja Srinivasan Saravanan, Felix Adams et al. (+2 more)
Foundation potentials (FPs) have emerged as a new basis for atomistic modeling. While their evaluation using average energy and force errors often indicates near-DFT accuracy, their performance in practical computational studies remains inconsistent. While recent
benchmarks evaluate FPs on downstream computational tasks, the underlying errors that determine task success or failure are not always clear. Here, we develop FP-DeErr, an application-oriented error-decomposition framework that resolves FP errors according to the physically meaningful quantities, configurations, and computational stages governing specific tasks. Rather than averaging errors over an entire
dataset, FP-DeErr uses decomposed error metrics devised for physically meaningful quantities, focusing on the configurations where errors arise and matter most. We demonstrate FP-DeErr by evaluating multiple state-of-the-art FPs on three fundamental tasks: force prediction for atomistic simulations, energy ranking for substitutional and vacancy orderings, and ion/vacancy migration. These error-decomposition metrics resolve force errors among highly accurate, large-error, and far-from-
equilibrium atoms; relative-energy errors among competing orderings, phases, and compositions; and ion migration errors among endpoints and along-path errors. By identifying where FP errors arise, this error decomposition provides targeted guidance for FP development. FP-DeErr also provides an open
benchmark, evaluation code, and a public leaderboard for rigorous FP assessment.
Read the full abstract ▾
All authors Kiyan Amirian, Ramanuja Srinivasan Saravanan, Felix Adams, Charles E Schwarz, Yifei Mo
Quantum Gases
Generating quantum error correcting codes from topological pre-thermal scars
William N. Faugno, Frank Barrows, Terry A. Loring et al. (+2 more)
Quantum many-body scars are rare nonthermal states embedded within otherwise thermalizing spectra, making them promising candidates for storing and manipulating
quantum information. However, a general framework that can both identify such states without prior knowledge of their microscopic scarring mechanism and determine when they enable a
quantum error correcting code has remained elusive. Here, we develop an end-to-end framework connecting nonthermal-state discovery to certifiable
quantum error correction using a many-body spectral localizer. By searching for states jointly localized in energy and a diagnostic observable in systems with a many-body grading
symmetry, the spectral localizer identifies candidate scars within dense many-body spectra in tandem with a topological index whose shifts determine their graded subspace. For suitable pairs of same-graded scars, the grading renders grading-odd errors exactly detectable, while their localization can suppress the logical action of sufficiently local grading-even error products, yielding an approximate Knill–Laflamme condition and an operator-
algebra quantum error-correction structure. We demonstrate the scar-identification framework in one- and two-dimensional density-difference-dependent bosonic models and in the PXP model, and explicitly construct the resulting approximate
quantum code in the one-dimensional bosonic system. Our results establish a systematic route from identifying nonthermal many-body states to exploiting them for protecting
quantum information, and position pseudospectral methods as a broadly applicable tool for discovering useful behaviors in interacting
quantum systems.
Read the full abstract ▾
All authors William N. Faugno, Frank Barrows, Terry A. Loring, Nathan Goldman, Alexander Cerjan
Materials Science
Bridging simulation length scales with cellular automata
John J. Karnes, Esteban D. Gadea, Shakkira Erimban et al. (+2 more)
Multiscale simulation requires coupling physics models that operate at different characteristic length and time scales, because no single method spans the range needed for most problems of interest. Moving to a coarser-grained representation unlocks longer length and time scales, but it discards the microscopic interactions that build morphology. A fine-grained model can be initialized from an arbitrary packing and left to self-assemble into a physically meaningful structure; a lower-resolution model cannot, and must inherit its starting configuration from a higher-fidelity simulation. The length scales accessible to the coarse-grained model are therefore set not by the coarse-grained method itself, but by the largest fine-grained configuration that can be affordably equilibrated. A representative example is the scale-up from particle-based molecular dynamics (MD) to a
lattice-based representation such as kinetic Monte Carlo (kMC). In this work, we present a cellular automata (CA) approach for generating arbitrarily large
lattice starting configurations. CA is a natural fit for this task: short-ranged local rules drive the
evolution of a
lattice, and their repeated application gives rise to emergent long-range order, thematically mirroring how short-ranged interactions in MD produce self-assembled morphology. We use a configuration from a higher-fidelity simulation as a training set and learn the CA rules from it via logistic regression. As a proof of principle, we develop these rules for a hydrated anion exchange membrane (AEM), generate new starting configurations, and
benchmark their performance in mesoscale kMC simulations against an MD-derived "ground truth." We then demonstrate the ability to generate substantially larger
lattices and show that their behavior in kMC is consistent with that of the smaller CA
benchmark configurations.
Read the full abstract ▾
All authors John J. Karnes, Esteban D. Gadea, Shakkira Erimban, Ignacio J. Bombau, Valeria Molinero
Soft Condensed Matter
Hidden amplitude and dynamical information in phase-separation spectra
Boliang Yu, Ruixin Zhou and Jiaxing Yuan
Framewise variance normalization removes fluctuation amplitude from an observation, but not from the dynamics that generate later patterns. The current normalized spectrum therefore need not determine its own future. We study this effect in three two-dimensional phase-separation models that change transport, add active driving, or suppress large-scale separation. For paired initial fields, their normalized spectra evolve identically in the linear regime. The restoring model provides an exact example: damping does not directly change how the normalized spectrum evolves when both equations are applied to the same field. It nevertheless changes the hidden amplitude, which alters the later nonlinear shape. An exact comparison separates the immediate effect of changing the equation from the effect of reaching a different state through earlier
evolution. It also reveals strong cancellation between these effects in the mobility and active models. As a practical test, spectral histories improve classification by about 4-6 percentage points at several later observation windows, although the gain depends on quench depth and spectral construction. Temporal spectra can therefore reveal dynamical consequences of information absent from every individual normalized frame.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Spectroscopy With Intelligent Feature Tracking for automated characterization of excited-state structure in semiconductor quantum dot devices
A. R. Huffman, Daniel Schug, Merritt Losert et al. (+6 more)
The characterization of excited-state structure in
semiconductor quantum dot (QD) devices is an important component of tuning them for
spin-
qubit operation. We present Spectroscopy With Intelligent Feature Tracking (SWIFT), a framework that combines machine-learning (ML)-assisted feature identification with physics-informed
geometric processing to extract energy-level splittings from pulsed-gate spectroscopy data. SWIFT isolates the relevant spectral features and exploits their characteristic geometry to reduce the two-dimensional spectroscopy analysis to a one-dimensional peak-detection problem. It further combines an ensemble-based confidence metric with sequential accumulation of rapid, low-SNR scans, allowing the inferred spectrum to be reevaluated as experimental evidence accumulates. Using Si/SiGe QD devices, we demonstrate SWIFT both offline and in real time, including automated tracking of QD excited states and lead resonances. Benchmarking on 255 manually labeled scans shows that SWIFT reduces the median splitting error to 0.05 mV from 0.11 mV for a classical baseline, with the largest improvement on lower-quality measurements. These results provide a path toward incorporating excited-state spectroscopy into autonomous QD characterization, tuning, and optimization, which will be essential in large-scale
quantum dot devices.
Read the full abstract ▾
All authors A. R. Huffman, Daniel Schug, Merritt Losert, Sanghyeok Park, Daniel King, Yuna Chun, Giordano Scappucci, M. A. Eriksson, Justyna P. Zwolak
Materials Science · Cross-listed from physics.chem-ph
Differentiable Solvation Shell Model for Rational Electrolyte Design
Hancheng Zhao, Hongyi Lin, Celia Kelly et al. (+1 more)
Tailoring Li+ solvation structures has emerged as a promising design principle across multiple Li metal battery (LMB) electrolytes, with localized high concentration electrolytes (LHCE) emerging as a leading candidate. However, rational design of these electrolytes remains limited by a poor quantitative understanding of how molecular properties govern Li+ solvation shell composition. Here we introduce a mean field modeling framework, built on an Ising model, that predicts solvation shell composition from donor number (DN), acceptor number (AN), molar ratio, and molecular size. This framework is end-to-end differentiable, which enables parameterization directly from molecular dynamics (MD) solvation structures via gradient-based optimization. Focusing on LHCE, the model achieves 10.7% RMSE and R2=0.87 for shell composition, 2.3% RMSE on free solvent ratio, and further reproduces solvation trends in real LHCE electrolytes, at a fraction of MD's cost. Our model also shows good generalizability on other electrolyte systems in addition to LHCE. Analysis of its interaction terms shows that DN dominates Li+ solvation energetics, providing a thermodynamic basis for empirical DN-based design rules. We further demonstrate the model's design utility on the LiTFSI/tetraglyme (G4) system absent from training. The model identifies fluorobenzene (FB) as a promising diluent and predicts a salt-concentration window with anion-rich solvation shells and low free solvent, favorable for stable anion-derived SEIs and high oxidative stability, respectively. This prediction is validated by higher-fidelity MD. This work establishes an interpretable differentiable framework for predicting Li+ solvation shell composition, with potential to extend to other electrolyte classes.
Read the full abstract ▾
All authors Hancheng Zhao, Hongyi Lin, Celia Kelly, Venkatasubramanian Viswanathan
Mesoscale and Nanoscale Physics
A magneto-mechanical gyroscope with spintronic readout
Andrea Meo, Francesca Garesci, Pedro Bossi Nunez et al. (+10 more)
Gyroscopes are essential elements in navigation, consumer electronics, robotics, and aerospace applications. Most micro electro-mechanical systems (MEMS) implementations rely on capacitive sensing mechanisms, which limit the dimensional scaling to the micrometer scale. In this work, we introduce a MEMS-like two-degree-of-freedom (2-DOF) gyroscope that exploits the rectification functionality of
magnetic tunnel junctions (MTJs) as its readout mechanism and as the transducer of the mechanical dynamics. Experimentally characterized MTJs have been used to calibrate and perform an experiment-informed design of the magneto-mechanical model combining micromagnetic theory with 2-DOF mechanical equations. We demonstrated that the output is linear with angular rate, and that the proposed device is able to extract the angular rate in dynamic cases exploiting a homodyne demodulation approach. The results open a path towards a compact, complementary metal-oxide
semiconductor (CMOS)-compatible readout pathway that relaxes reliance on tight capacitive gaps and motivates multi-physics designs of the device.
Read the full abstract ▾
All authors Andrea Meo, Francesca Garesci, Pedro Bossi Nunez, Maddalena Fiorentino, Teresa Natale, Ludovico Dindelli, Victor Lopez-Dominguez, Banibrato Sinha, Riccardo Tomasello, Francesco Dell'Olio, Pedram Khalili Amiri, Mario Carpentieri, Giovanni Finocchio
Soft Condensed Matter
From agent-based dynamics to a kinetic theory of jellyfish swarms
Nicolas Perez, Erik Gengel, Zafrir Kuplik et al. (+1 more)
Massive jellyfish swarms observed at sea can extend over tens of kilometres and contain millions of individuals, yet the mechanisms governing their formation and large-scale dynamics remain poorly understood.
Agent-based models provide a framework for describing this dynamics based on jellyfish responses to ocean currents and environmental cues, but become computationally prohibitive when extended to large populations and spatial scales relevant to ocean circulation. Here we derive a continuous kinetic theory from an active-particle model of jellyfish motion. The resulting Fokker-Planck framework incorporates transport by prescribed currents,
stochastic reorientation, direct interactions and stimulated steering, allowing chemical signalling to be represented through a coupled field. We further derive a hydrodynamic closure for large swarms by exploiting the separation between fast orientational and slow spatial dynamics, yielding a reduced density equation suitable for implementation in ocean-current models. This framework provides a route from individual behavioural mechanisms to continuum descriptions of jellyfish populations and establishes a basis for constraining model parameters using observations and in-situ measurements. This approach offers a theoretical foundation for future numerical prediction of large jellyfish swarm formation and
evolution in realistic ocean flows.
Read the full abstract ▾
All authors Nicolas Perez, Erik Gengel, Zafrir Kuplik, Eyal Heifetz
Statistical Mechanics
Distribution of currents in a system of active particles with biased hops and Ising interactions
Evgeniy Khain, Shriram Ramesh and Vladimir Chernyak
We consider an ensemble of particles performing a biased random walk on a two-dimensional
lattice. Due to the adhesion between particles (nearest-neighbor Ising interactions), the probability of hopping depends on the number of neighbors and the strength of adhesive interaction. The asymmetry in the hopping directions leads to a macroscopic current of particles through the system. We theoretically compute the distribution of currents and verify the results in
stochastic particle simulations. To make theoretical progress, one has to determine the probabilities of various particle configurations such as single particles, pairs, and different configurations of three-particle clusters. These probabilities are theoretically derived by formulating rate equations for the concentrations of various structures resembling Becker-Döring cluster equations. One intriguing finding is that the concentration of left-handed triplets is not equal to the concentration of right-handed triplets for non-zero asymmetry of hops and non-zero interaction between particles.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Gauge-covariant magnetic Bloch sums for general multiorbital Hofstadter models
Hao Shi, Tianyu Qiao, Wangqian Miao et al. (+3 more)
We formulate a unified treatment of the Hofstadter problem for general two-dimensional multiorbital Peierls tight-binding
Hamiltonians using a gauge-covariant
magnetic Bloch-sum basis. The construction retains the full Bravais geometry, arbitrary intracell orbital positions, and the original hopping table, so
lattice geometry, orbital
embedding, hopping range, and orbital content can all be handled within the same framework. At rational flux $\Phi/\Phi_0=p/q$, commuting
magnetic translations reduce the Peierls
Hamiltonian to minimal $qN_{\rm orb}\times qN_{\rm orb}$ blocks. Their dimension depends only on the flux through the primitive
cell, even when the fractional orbital coordinates are irrational. Electromagnetic gauge transformations act by
unitary conjugation within the construction and do not alter the required
magnetic supercell. We derive an explicit sparse
matrix in an oblique Landau gauge and establish the associated band counting, spectral redundancy, Chern-number formulation,
magnetic spatial constraints, and flux periodicity. Numerical examples include elementary
lattices, topological and flat-band models, and a spinful 22-band Wannier
Hamiltonian of monolayer $\mathrm{MoS}_2$, demonstrating a direct interface with first-principles electronic-structure calculations. As a complementary representation, we also derive exact generalized Harper equations from the same hopping data and relate them to the finite
magnetic-Bloch blocks.
Read the full abstract ▾
All authors Hao Shi, Tianyu Qiao, Wangqian Miao, Jin-Tao Jin, Quansheng Wu, Xi Dai
Materials Science · Cross-listed from cs.AI
The convergent laboratory: when AI reasoning, autonomous experiments, high performance and quantum computing reshape chemistry
Eliu Huerta, Xiaoyun Wang, Geetika Gupta et al. (+7 more)
This Comment emerges from TPC26 (https://tpc26.org), a conference convening leaders from academia, national laboratories, and industry who are reshaping materials science discovery. The meeting explored how AI, autonomous
agents, self-driving labs, higher performance and
quantum computing converge to amplify their individual impact on materials science discovery. The perspectives here reflect the firsthand experiences of researchers at these frontiers and capture the essence of this global endeavor. As AI-driven
reasoning, autonomous agentic frameworks, self-driving laboratories, and fault-tolerant
quantum processors mature simultaneously, we offer this Comment as a reference at what we believe is a tipping point of transformative advances and productive disruption in the chemical sciences.
Read the full abstract ▾
All authors Eliu Huerta, Xiaoyun Wang, Geetika Gupta, Edward H. Sargent, Cameron J. Owen, Victor Fung, Abhishek Mitra, Austin Cheng, Emma Bouchard, Shams Mehdi
Mesoscale and Nanoscale Physics
Fast universal parametric spin control in an acoustically modulated quantum dot
Mateusz Kuniej and Michał Gawełczyk
Quantum communication, distributed computing, and hybrid architectures rely on nodes enabling coherent control of
qubits and coupling to propagating
quantum modes. While
semiconductor quantum-dot (QD)
spins couple to microwave and optical
photons, weak interaction with mechanical waves has limited the integration of single-QD
spin qubits into on-chip, acoustically coupled hybrid systems. The existing theory of acoustic QD
spin control suffers from a limited range of rotation-axis angles, enforcing complex realizations of gate primitives and long gate times, leaving little margin against decoherence from trion decay and quasi-static nuclear-
spin noise. We propose parametric control that overcomes these problems. We use far-detuned optical coupling to a trion state to dress and thus mix
spin states, combined with acoustic modulation of the optical transition energy. Instead of relying on direct acoustic resonance with the
spin splitting that leads to significant bottlenecks, we induce
spin rotations parametrically via resonance with the dressed-
spin splitting. We thus develop a
spin analog of the “swing-up” charge-state excitation. Our scheme provides fast universal
qubit control with nearly arbitrary rotation axes. Our ${\sim}$155 ps Pauli-$X$ gate duration is ${\sim}290\times$ faster than in the previous acousto-optical formulation and ${\sim}14\times$ faster than optical Faraday-geometry
spin rotation. The parametric scheme naturally enables higher-harmonic processes. Numerical simulations for ${\sim}44$ GHz acoustic driving show average gate fidelity $\ge99.9\%$ even for uncooled nuclear-
spin environments of GaAs and InAs QDs for trion lifetime $\gtrsim1.25$ ns. These metrics suggest practically usable control and may introduce a
spin-
phonon interface with high interaction rates, versatility, and multi-
phonon processes, essential for future acoustically coupled hybrid architectures.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
First principles calculations of electric-field-driven topological phase transitions in silicene, germanene and stanene
Julián Antonio Villarreal Murúa, Pablo Roura-Bas, Javier Daniel Fuhr et al. (+1 more)
The emergence of two-dimensional topological materials, particularly the group-14 monolayers known as silicene, germanene, and stanene has opened promising pathways for next-generation nanoelectronics and spintronics. Their buckled honeycomb structure and strong
spin-orbit coupling allow for bandgap engineering via a perpendicular electric field, leading to topological phase transitions (TPTs) from non-trivial to trivial insulating states. However, precise determination of the critical electric field $E_z^{\text{cr}}$ at which these transitions occur remains challenging, with tight-binding models often underestimating these values. Here, we present a first-principles framework that combines density-functional theory (DFT), maximally localized Wannier functions, and
evolution of the Wannier charge centers (WCC) to accurately characterize TPTs in silicene, germanene, and stanene through the $\mathbb{Z}_2$ topological invariant. In contrast to earlier work, at each electric-field strength we run fully self-consistent ab initio simulations to obtain the screened electronic structure, accounting for the material's dielectric response from both electrons and ions. From these converged results we construct a Wannier tight-binding
Hamiltonian at each electric field strength, which then enables a gauge-invariant calculation of the $\mathbb{Z}_2$ topological invariant. This methodology yields significantly more accurate numerical predictions of $E_z^{\text{cr}}$, $0.020$ and $0.250$ V/Å for silicene and germanene, respectively. Compared to previous approaches, our framework delivers a marked quantitative improvement for predicting topological phase boundaries, essential for guiding the design of topological field-effect transistors and electrostatically controlled
quantum devices based on two-dimensional materials.
Read the full abstract ▾
All authors Julián Antonio Villarreal Murúa, Pablo Roura-Bas, Javier Daniel Fuhr, Ricardo Faccio
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Hawking Radiation in non-Hermitian Microscopic Analogues
Diego F. Munoz-Arboleda, Cristiane Morais Smith and Marcus Stålhammar
Non-Hermitian systems have recently emerged as a convenient platform to realize black-hole physics. Here, we propose a microscopic open
quantum system, namely a fermionic tight-binding chain coupled to Markovian reservoirs, which emulates black-hole properties. The resulting quadratic Lindbladian admits an effective non-Hermitian limit that produces a gain and loss
lattice model with a non-reciprocal next-nearest-neighbor hopping. The rapidity spectrum of the full Lindbladian forms tilted exceptional cones that define an effective Painlevé-Gullstrand geometry and separates into black-hole and white-hole sectors, while steady-state particle densities and currents retain clear signatures at the horizon positions. We then analyze the effective non-Hermitian
Hamiltonian that arise from the microscopic
quantum system. The biorthogonal flux identifies the outgoing exterior and interior channels. Finally, we introduce a fermionic Gaussian Nambu extension and formulate Hawking-pair witnesses through frequency-resolved scattering, nonlocal density-density correlations, and anomalous Hawking-partner amplitudes. The resulting correlations display analogue Hawking radiation signatures, while the frequency-resolved Hawking-partner correlations satisfy the fermionic covariance-positivity constraint. These results establish a connection between microscopic open-system dynamics, emergent non-Hermitian geometry, and fermionic many-body probes of analogue Hawking radiation.
Read the full abstract ▾
Quantum Gases · Cross-listed from hep-th
Robin Löwenberg and Julian Sonner
We propose an analog
quantum-simulation protocol based on a
lattice of atomic ensembles and time-averaged Floquet dynamics to construct the four-body potentials that typically appear in bosonic BFSS-like
matrix quantum mechanics. In contrast to gate-based digital implementations requiring deep
circuits, our approach generates the target model through a fixed set of control stages per Floquet cycle, keeping the number of consecutive
unitaries constant with respect to the
matrix size $N$. The principal scaling cost in our construction is given by the frequency range required to control the growing
lattice. We show that this cost grows at most as $\mathcal{O}(N^3)$, giving a
polynomial scaling route to large$-N$, attractive to experimental implementation. Additionally, we demonstrate that the coupling parameter can be tuned beyond $\mathcal{O}(1)$, enabling the simulation of strong-coupling physics necessary for holographic phases.
Read the full abstract ▾
Superconductivity
Pair density wave order from non-symmorphic momentum symmetry
Matteo Dürrnagel, C. Alexander Baum, Michael Klett et al. (+2 more)
We develop a class of microscopic
lattice models in which pair density wave order emerges in the asymptotically exact weak coupling limit. The underlying mechanism is due to non-symmorphic momentum
symmetry implied by the models' projective space group representation of electrons. Our mechanism suggests moiré systems and extended s-wave altermagnets as potential hosts for pair density wave order.
Read the full abstract ▾
All authors Matteo Dürrnagel, C. Alexander Baum, Michael Klett, Lennart Klebl, Ronny Thomale
Strongly Correlated Electrons · Cross-listed from quant-ph
Matrix Product Belief Propagation
Gabriel Woolls, Shahin Jahanbani, Adarsh Pashikanti et al. (+3 more)
We introduce "
matrix product belief propagation" (MP-BP) as a controlled method for the approximate contraction of two-dimensional tensor networks and graphical models, which generically leads to a quadratic reduction of errors relative to existing methods: at similar computational effort, the number of accurate digits is asymptotically doubled. For infinite systems, MP-BP can be understood as a practical implementation of Baxter's corner-transfer-
matrix method; for reflection-symmetric networks, it further coincides with the boundary
matrix-product-state and corner-transfer-
matrix renormalization group
algorithms as conventionally implemented. In the limit of unit
matrix-product rank, MP-BP is equivalent to belief propagation, and more generally, can be understood as a generalization of BP in which the "messages" live on surfaces and are assumed to have a
matrix-product factorization. We further extend the quadratic improvement to the computation of expectation values, and numerically demonstrate the qualitatively improved convergence for a variety of classical and
quantum 2D tensor network problems.
Read the full abstract ▾
All authors Gabriel Woolls, Shahin Jahanbani, Adarsh Pashikanti, Matthew T. Fishman, Joseph Tindall, Michael P. Zaletel
Quantum Gases
Quantum Quenches across the Bose-glass Transition
Bo Song, Shaurya Bhave, Emmanuel Gottlob et al. (+2 more)
Due to their intrinsic interplay between long-range order and quasi-disorder, quasicrystalline systems provide a rich platform for investigating novel
quantum phenomena. Here we study the non-
equilibrium dynamics following
quantum quenches across the superfluid to Bose-glass transition using ultracold
bosons in an optical quasicrystal. Fast quenches into the Bose glass regime induce a
quantum walk in momentum space that spreads over increasingly higher momentum orders. Conversely, quenches into the superfluid regime initiate a real-space
quantum walk of initially localized atoms, forming a light-cone-like structure bounded by Lieb-Robinson limits. Characteristic timescales reveal strong links to the underlying
Hamiltonian and are governed primarily by quasi-disorder strength in the Bose glass phase, and by tunneling strength in the superfluid phase. Finally, we analyze slower quenches into deeper
lattices and observe the decay of coherence across the phase transition.
Read the full abstract ▾
All authors Bo Song, Shaurya Bhave, Emmanuel Gottlob, Leanne Reeve, Ulrich Schneider
Mesoscale and Nanoscale Physics
Variable Charge State, Magnetic Excitations, and Kondo Effect of Sm/g/Ir(111)
Shixuan Shan, Tamara de Ara, Lina Liu et al. (+7 more)
Using low-temperature scanning tunneling microscopy we investigate the charge state,
magnetic excitations, and Kondo features of individual Sm adatoms on
graphene/Ir(111). Depending on the number and distance of their neighbors, Sm atoms can be in two discrete charge states. At certain distances, a reversible transition between these two states is induced by the electric field of the STM tip leading to concentric charge rings in the images. Only atoms in one of the two charge states exhibit
magnetic excitations in d$I$/d$V$ spectra. Two such excitations are located at 35~meV and 54~meV and related to transitions from the $J = 1/2$ ground state doublet to the first
crystal field split $J = 3/2$ multiplet. Together with the intra-atomic exchange excitations at higher energy, these observations indicate that Sm transfers one $6s$ electron to the substrate while it retains its gas-phase $4f$ filling. New for lanthanide adatoms, we observe a Kondo resonance. The Zeeman splitting of the Kondo peak reveals that Sm retains its large gas-phase $g$-factor. Comparison of d$I$/d$V$ spectra to cotunneling theory yields the
crystal field acting on the $4f$ shell and, consequently, on the $J = 3/2$ quadruplet, confirms Sm$^+$ as the ground state, and identifies Sm$^{2+}$ as being energetically close, thereby rationalizing our observation of variable charge states.
Read the full abstract ▾
All authors Shixuan Shan, Tamara de Ara, Lina Liu, Zhipeng Wang, Marina Pivetta, François Patthey, Tadahiro Komeda, Daria Kývala, Jindřich Kolorenč, Harald Brune
Materials Science
From Electronic Structure to Environmental Remediation: Adsorption of Ionized Glyphosate on COOH-Modified Carbon Nanotube
H. T. Silva, L. C. S. Faria, C. Aguiar et al. (+2 more)
Glyphosate is a widely used herbicide whose persistence and toxicity in aquatic and terrestrial environments demand efficient removal strategies. Here we employ GFN2 xTB calculations with implicit ALPB aqueous solvation and automated docking to investigate the adsorption of all five pH dependent ionized forms of glyphosate (G1-G5) on (10,0) single walled carbon nanotubes covalently functionalized with carboxyl groups at 0-25% coverage. Adsorption energies reveal a clear charge dependent trend: the dianionic (G4) and trianionic (G5) species exhibit the most negative binding energies over the entire functionalization range, while the protonated and neutral forms (G1, G2) bind weakly, approaching reversible adsorption at high COOH contents. The deprotonated form G5 strengthens from -2.17 eV on pristine CNT to about -5.7 eV at 10% and 25% functionalization, with a local minimum near 15-20% COOH due to steric and electrostatic crowding of adjacent groups. Decomposition of the solvation free energy shows dominant electrostatic stabilization complemented by increasingly favorable hydrogen bond contributions as carboxyl density grows. All complexes display very small HOMO-LUMO gaps (0.02-0.22 eV), indicating high electronic sensitivity to adsorption and functionalization. Overall, CNT+COOH systems can operate in both strong capture and regenerable regimes depending on glyphosate ionization state, offering a tunable platform for pH responsive remediation.
Read the full abstract ▾
All authors H. T. Silva, L. C. S. Faria, C. Aguiar, T. A. Aversi-Ferreira, I. Camps
Statistical Mechanics
Non-reciprocally interacting Ornstein-Uhlenbeck processes: Exceptional points, Anomalous relaxation, Pseudo-equilibrium and Boundary refrigeration
Soumya Kanti Pal and Shamik Gupta
Non-reciprocal interactions are ubiquitous in active, biological, and disordered systems, generically driving them out of
equilibrium. Here, we introduce a hierarchy of non-reciprocally interacting Ornstein-Uhlenbeck (NROU) models governed by a tunable non-reciprocity parameter $g$. At a special point $g=g^*$, the drift
matrix becomes non-diagonalizable, realizing exceptional points (EP's) of different orders, where
eigenvalues and eigenvectors simultaneously coalesce. The hierarchy encompasses non-reciprocally coupled dimers, their disordered counterparts, and a many-body chain exactly mapping onto the paradigmatic Hatano-Nelson model in the arena of non-Hermitian
quantum systems. For the disordered model, we show that the distribution of the EP location $g^*$ across disorder realizations develops a universal edge singularity precisely at the clean-system EP, and is manifestly non-self-averaging. Across all models, we find that at the EP, the usual exponential relaxation of the autocorrelation and covariance functions is dressed by a
polynomial-in-time prefactor whose degree is set by the order of the EP and whose detailed structure encodes the spatial architecture of the chain. At complete asymmetry, the many-body chain exhibits “pseudo-
equilibrium”: its steady-state distribution factorizes into
equilibrium-like single-particle measures despite a nonzero steady-state current. Moreover, the $N$-particle interacting system decomposes into $N/2$ independent complex OU processes. Finally, using the Harada-Sasa relation, we obtain a closed-form expression for the total steady-state heat dissipation and uncover a boundary refrigeration effect, in which the boundary particles switch from acting as a hot to a cold reservoir as the non-reciprocity is tuned.
Read the full abstract ▾