Mesoscale and Nanoscale Physics
Fragmented and symmetry-restored condensates in a three-site Bose ring: exchange versus umklapp
A. Siddiki
We study $N$
bosons on a three-site ring with nearest-neighbour hopping, density-assisted hopping of the opposite sign, and an on-site interaction, written equivalently as three momentum modes $q=0,\pm1$ with a channel-dependent quartic vertex. As the density-assisted term grows it inverts the band, and exact diagonalisation up to $N=400$ shows a first-order ground-state transition from the $q=0$ condensate to a state with $\avg{n_{+1}}=\avg{n_{-1}}\simeq N/2$; the avoided-crossing gap closes faster than exponentially with $N$. In its symmetric eigenstates this state is fragmented in the Penrose-Onsager sense, and at leading order in $N$ it has the energy of a Gross-Pitaevskii (GP) standing wave, as expected for a few-mode mean-field system. We distinguish two cases by switching off umklapp scattering, which is available because $2\cdot(+1)\equiv-1$ on three sites, and by varying the on-site interaction. Without umklapp, $n_{+1}-n_{-1}$ is conserved, the eigenstates form a rotor tower whose lowest member is a fragmented Fock state, and the transition leads to fragmentation exactly when the $\pm1$ interaction is attractive, as predicted by Nozières' exchange argument with the sign of the interaction reversed; otherwise the system forms a single current-carrying condensate. With umklapp, the standing wave is pinned to three positions, the three momentum sectors become degenerate exponentially in $N$, and coherent admixture of the $q=0$ mode stabilises the standing wave over a wider range; the exact ground state is then a number-squeezed, momentum-projected standing-wave condensate rather than a robustly fragmented state.
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Mesoscale and Nanoscale Physics
New dimensions in magnetism and superconductivity via 3D nanoprinting with focused electron and ion beams
Claire Donnelly, Rosa Córdoba and Amalio Fernández-Pacheco
The extension of nanoscale
quantum materials to the third dimension brings new possibilities to geometrically tune emergent properties, emulating or indeed going beyond the physics of bulk materials, with exciting implications for high-density technological integration. Realising such three-dimensional architectures requires nanofabrication techniques that not only enable complex 3D geometries, but also deliver functional
quantum materials with emergent phenomena. Recent advances in focused electron- and ion-beam induced deposition (FEBID and FIBID) have made 3D nanopatterning of functional materials in complex geometries increasingly feasible, paving the way for the experimental realisation of new phenomena and device prototyping. In this review, we discuss the use of FEBID and FIBID 3D nanopatterning of superconducting and
magnetic materials. We address the underlying mechanisms, and capabilities of these techniques, focusing on the physical phenomena that become accessible. Considering the resolution of the techniques in the context of the fundamental lengthscales of the materials, we discuss the emergent effects that arise due to three dimensional geometries in
magnetic and superconducting nanostructures, and highlight perspectives for future developments of the techniques.
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Materials Science
A Scale-Separated Full-Field Monopole Method for Precipitation Modelling
C. W. Sinclair
A scale-separated monopole method is developed for full-field prediction of precipitation under conditions where particle-scale
diffusion fields coexist with solute variations over much larger distances. Precipitates are represented by monopole Green's-function solutions, providing a particle-based description of interacting particle growth and dissolution. The direct quasistatic formulation is validated against transient finite-difference calculations and a conventional Kampmann–Wagner numerical model, but becomes inappropriate when spatially heterogeneous particle populations generate slowly relaxing long-wavelength concentration fields. An Ewald decomposition is therefore used to separate the
diffusion field by spatial scale. Screened particle-scale fields are treated quasistatically, while the complementary long-range field evolves by transient
diffusion. The resulting hybrid formulation retains explicit particle-level precipitation kinetics while allowing mesoscale solute redistribution to evolve on its physical timescale. Application to Al–Sc demonstrates that a transient depletion field generated by localized precipitation can suppress subsequent nucleation and produce persistent spatial variations in precipitate number density and volume fraction.
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Strongly Correlated Electrons
Complete Entanglement Structure of the Kitaev Honeycomb Spin Liquid from Exact Tensor Networks
Hidehiro Saito and Chisa Hotta
While most of the features of the Kitaev honeycomb model are already clarified from the combined ${\mathbb Z}_2$ plaquette and Majorana
fermion picture, we show that retrieving the exact
quantum many-body form gives a clue to fix the remaining issues on its
spin liquid property. We provide an exact two-dimensional tensor network description of a full set of solutions from a random product state, by sequential
quantum-number projection and Gutzwiller projection, both expressed as local
matrix-product operators of dimension $D=2$. The ground and excited states share the same bond dimension yet exhibit distinct Schmidt spectra, distinguishing their area-law and volume-law
entanglement. We demonstrate that the topological
entanglement entropy emerges for all eigenstates only after the Gutzwiller projection onto the physical
spin Hilbert space, where the gauge constraint removes exactly half of the Schmidt states. This establishes that excited states are likewise topologically ordered. We further show that there exists a projection-induced collapse of the wave function into a single gauge sector in the Parton mean-field states that is known to give a good description of the
spin liquids. The demonstrations on the $S=1/2$ kagome and triangular Heisenberg models suggest that the present perspective is applied to a wider class of models hosting ${\mathbb Z}_2$
spin liquids. Our finding visualizes a bulk-boundary correspondence with the Wilson-loop characterization of topological order.
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Materials Science
Sliding and stacking thin homo-monolayers from energy landscapes and combinatorics
Jose D. Mella, Jose Luis Cabellos, Bernardo S. Mendoza et al. (+1 more)
Structure leads to function: Knowing all possible ways to stack and slide identical monolayers enables the design of functionalities such as nonlinear optical responses and ferroelectricity in layered materials. Besides, mounting experimental evidence points to differing stacking configurations in few-monolayer and bulk samples. To exemplify the core concepts for stacking arbitrary monolayers, ground-state and metastable non-moiré SnSe stacks were first identified using density functional theory and employed to validate a “divide and conquer” combinatoral approach for determining the most probable stacking configurations in materials with an arbitrary number of identical monolayers. A small number of point groups accounts for all possible stacks, which explains experimental second-harmonic optical responses. Finite-temperature effects are also studied despite the granularity of available data. This comprehensive framework readily generalizes to provide a predictive description of arbitrary metastable few-homomonolayer stacks.
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All authors Jose D. Mella, Jose Luis Cabellos, Bernardo S. Mendoza, Salvador Barraza-Lopez
Superconductivity
Competing charge density-wave and superconducting states in a quasi-one dimensional two-band electron-phonon model
C. Bourbonnais, A. Ghosh and M. Haguier
We apply the renormalization group method to examine the interplay between the charge density-wave and superconductivity phases in two quasi-one-dimensional tight-binding electronic bands coupled by the electron-
phonon interaction. The electronic and
phonon energy scales are embedded in a two-cutoff scaling scheme at finite temperature for the renormalization group flow equations of intra- and inter-band
phonon-mediated interactions between electrons. At the one-loop level different regimes of renormalization are derived covering both the adiabatic and antiadiabatic domains for small and large
phonon frequencies. Finite temperature phase diagrams as a function of nesting frustration of the electron spectrum are thus obtained. The possibilities for superimposed charge density-wave and superconducting ordered states are given. The emergence of domes of superconductivity resulting from
quantum critical reinforcement of Cooper pairing by charge density-wave order fluctuations is found. The impact of the multiband character of the electronic structure on the ordering temperature of superconductivity,
quantum criticality, and isotope effect is discussed.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Cups and Gates II: Operads, twists, and addressable intra-code gates
Nikolas P. Breuckmann, Margarita Davydova, Jens Niklas Eberhardt et al. (+2 more)
In Part I, we introduced a general framework for constructing logical gates in
quantum CSS codes from cohomology invariants, focusing on cup products and their generalizations from topological to qLDPC codes. In particular, we produced a family of $C^{k-1}Z$ logical gates that we called copy-cup on $k$ copies of the same
quantum code implemented by finite-depth
circuits. Here, we vastly extend this framework by introducing twists incorporating code automorphisms, higher twisted cohomology operations, and folding operations in relative cohomology. The framework includes operations lifting coefficients from $\mathbb{Z}/2$ to $\mathbb{Z}/2^k$, enabling all diagonal logical gates such as single-
qubit rotations $\operatorname{R}(2\pi/2^k)$. Composing these operations with maps that select cohomology classes yields addressable logical gates. Examples include addressable $T$ gates on three- and four-
tori and gates in qLDPC codes beyond topological ones. We introduce cohomology operations, such as the higher twisted Pontryagin powers, that to our knowledge have not previously appeared in the mathematics literature. These operations arise from $E_\infty$-structures on cochains, with explicit constructions using cyclic resolutions and the surjection operad. We expect these results to be of independent interest in homotopy theory. Our formalism applies much more broadly to chain complexes carrying suitable operadic structures, and we expect this operadic perspective to uncover further connections between homotopy theory and fault-tolerant
quantum gates.
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All authors Nikolas P. Breuckmann, Margarita Davydova, Jens Niklas Eberhardt, Lucas Ferdinand Hallwirth, Nathanan Tantivasadakarn
Superconductivity
Solid-state reaction synthesis of superconducting refractory-metal germanides for Ge/SiGe quantum devices
Sebastiaan R. Roelofs, Jan Cornelis Wolff, Nick van Loo et al. (+3 more)
Solid-phase reactions offer a route to integrate
superconductors into Ge/SiGe
heterostructures, but forming high-quality superconducting layers near the buried Ge
quantum well remains challenging. We investigate reactions of V, Ta, and Nb with elemental Ge and with the Si$_{0.2}$Ge$_{0.8}$ barrier of Ge/SiGe
heterostructures at processing temperatures of 365-390 $^\circ$C. Cross-sectional electron microscopy and low-temperature electrical transport show that deposition on Ge at 390 $^\circ$C, in which approximately 2 nm metal increments are separated by growth stops for in-situ annealing, produces reactions throughout the deposited films and superconducting transitions at approximately 0.14 K for V-Ge, 2.1 K for Ta-Ge, and 2.8 K for Nb-Ge. The Nb-Ge layer has an out-of-plane critical field of approximately 0.8 T at 2.1 K. In the
heterostructure samples, intermixing is confined to regions approximately 5-12 nm thick near the metal-SiGe interface, leaving a substantial residual metal layer. Microscopy and transport together suggest that this residual film dominates the measured superconducting response. These results establish low-temperature formation of superconducting refractory-metal-Ge layers while identifying the limited interfacial reaction as the principal obstacle to extending this approach toward the buried
quantum well.
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All authors Sebastiaan R. Roelofs, Jan Cornelis Wolff, Nick van Loo, Karina L. Hudson, Giordano Scappucci, Greg P. Mazur
Strongly Correlated Electrons · Cross-listed from hep-th
From Critical Zero Modes to Interior Dynamics in Holographic Superconductors
Yan Liu and Hong-Da Lyu
We study how the critical behavior of holographic
superconductors controls the interior geometry of charged black holes. Although the exterior condensate vanishes at criticality, the critical zero mode develops logarithmic oscillations near the Reissner–Nordström Cauchy horizon, rendering the interior critical limit nonuniform. We show that the transmitted critical-mode amplitude, together with local Cauchy-horizon quantities, fixes both the leading Einstein–Rosen collapse $\Delta z_{\rm ER}$ width and the phase $\Theta_J$ in the subsequent Josephson regime. If the condensate obeys $t\equiv1-T/T_c\propto\epsilon^{2r}$, then $\Delta z_{\rm ER}\propto t^{1/r}$ and $\Theta_J\propto t^{-1/r}$. This Josephson phase is transferred to the first Kasner epoch, producing oscillatory Kasner exponents and an accumulation law $t_n\sim n^{-r}$ for successive zeros of the scalar velocity. The critical zero mode fixes the leading collapse and phase coefficients, which are quantitatively confirmed by fully nonlinear solutions in both the ordinary and tricritical cases. At low temperature, the interior instead depends on the infrared completion of the zero-temperature geometry. Thus near-critical scaling is governed by critical-mode transmission, whereas the low-temperature behavior is controlled by the infrared endpoint.
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Mesoscale and Nanoscale Physics
Tara Murphy, Lorenzo Peri, Giovanni A. Oakes et al. (+8 more)
Electron cotunneling in
semiconductor quantum dots is a higher-order tunneling mechanism that connects initial and final charge states through energetically inaccessible virtual intermediate configurations. In
quantum-dot arrays, such processes can produce simultaneous charge motion across multiple tunnel junctions and enable transitions that would otherwise be suppressed by Coulomb blockade. Here, building on an earlier proof-of-principle demonstration, we investigate
radio-frequency (rf)-driven correlated cotunneling and its application to dispersive
quantum-dot readout. Using both theoretical modeling and experimental measurements in two different foundry-fabricated silicon devices, we show that an external rf drive can induce correlated cyclic single-electron transitions, resulting in enhanced charge-polarization of the system. We develop a general theoretical framework for rf electron-cascade readout, which exploits cotunneling events in
quantum-dot systems with three or more dots to produce a relative signal enhancement, and extend its experimental demonstration to a gate-sensed device architecture. Our results establish the operating principles of rf electron-cascade readout and provide a route to increased dispersive readout fidelity in
semiconductor quantum computing architectures.
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All authors Tara Murphy, Lorenzo Peri, Giovanni A. Oakes, Jacob F. Chittock-Wood, Ross C. C. Leon, Fabrizio Berritta, Amber Heskes, David Wise, Anasua Chatterjee, Ferdinand Kuemmeth, M. Fernando Gonzalez-Zalba
Strongly Correlated Electrons
Unveiling High-Energy Ultrafast Responses Driven by Fermi-Level Gap Opening in Charge-Density Waves
Qiong Wu, Tianchen Hu, Junhan Huang et al. (+8 more)
Ultrafast pump-probe spectroscopy is indispensable for investigating interactions, collective excitations, and nonequilibrium dynamics in
superconductors and correlated electron systems. However, how a small gap opening near Fermi surface affects the spectral changes in the high-energy interband transition region remains elusive. To address this issue, we perform systematic studies of carrier relaxation dynamics in the prototype charge-density-wave (CDW) material EuAl4. We find that the CDW gap shrinks substantially under optical pumping. This band renormalization strongly modulates interband transitions associated with the gap edge, inducing a pronounced transient reflectivity change at the corresponding probe energies. These results establish a direct link between low-energy order-parameter dynamics and high-energy spectral responses, providing a general framework for interpreting transient signals in gapped
quantum materials.
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All authors Qiong Wu, Tianchen Hu, Junhan Huang, Yongjie Liu, Fei Sun, Shuxiang Xu, Li Yue, Zijian Lin, Xinyu Zhou, Tao Dong, Nan-Lin Wang
Superconductivity
Paramagnon softening upon doping in oxychloride cuprate superconductors
Chafic Fawaz, Léo Gaspard, Laura Chaix et al. (+15 more)
Understanding how
magnetic excitations and exchange interactions evolve with doping is crucial for deciphering the physics that shapes the phase diagram of high-temperature cuprate
superconductors. Here, we clearly determine the behavior of the paramagnon dispersion in the oxychloride cuprate Na$_{x}$Ca$_{2-x}$CuO$_2$Cl$_2$ up to the highest doping level. We find that the paramagnon bandwidth, defined by the energy at the $X$ zone boundary $(0.5,0,0)$, remains unchanged within experimental uncertainty, even though it exhibits significant broadening. In contrast, along the nodal direction $\Gamma-M$ (i.e., from $(0,0,0)$ to $(0.5,0.5,0)$), the paramagnon energy shows a marked softening with doping, with a shift of up to $\Delta E\sim150$ meV at the midpoint of the zone for the highest doping, which is about half of its initial value in the antiferromagnetic phase. Calculations of the dynamical
spin structure factor for a one-band Hubbard model, including hopping terms up to the third-nearest neighbor ($t^{\prime\prime}$), explain this behavior and accurately reproduce the observed wave vector dependence and directional variation in the Brillouin zone.
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All authors Chafic Fawaz, Léo Gaspard, Laura Chaix, Luca Laveder, Benjamin Bacq-Labreuil, Victor Porée, Flora Yakhou-Harris, Kurt Kummer, Nicholas B. Brookes, Alessandro Nicolaou, Hajime Yamamoto, Yuichi Okazaki, Ikuya Yamada, Masaki Azuma, David Santos-Cottin, Marie-Aude Méasson, Benjamin Lenz, Matteo d'Astuto
Soft Condensed Matter
Metastability and nucleation of bubbles in active chiral systems
Raphael Maire, Alessandro Petrini, Umberto Marini Bettolo Marconi et al. (+1 more)
Bubbles frequently emerge in dense chiral active fluids, yet it remains unclear whether they result from an instability of the homogeneous state or from rare nucleation events within a metastable phase. Here we develop a nucleation theory for chiral bubble formation by reducing the hydrodynamic equations to a single collective coordinate, the bubble radius. This reduction yields an effective nonlinear potential that captures the radial dynamics and predicts distinct stable, metastable, and unstable regimes of the homogeneous state. In the metastable regime, the theory identifies a critical bubble radius and an associated effective mechanical-work barrier, while its large-radius behavior determines whether bubble growth saturates at a finite size or becomes unbounded. We further analyze the stability of circular bubbles against noncircular perturbations, finding growing modes that can lead to elongation and breakup. The theoretical predictions are tested against event-driven molecular-dynamics simulations of chiral hard disks, which reproduce the predicted trends in the critical radius, nucleation barrier, and selected bubble size. Our results establish a unified framework for stability and nucleation in chiral active fluids and suggest routes to control bubble formation in experiments with spinning colloids and chiral spinners.
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All authors Raphael Maire, Alessandro Petrini, Umberto Marini Bettolo Marconi, Lorenzo Caprini
Materials Science
Computing at the Edge Enabled by Indoor Photovoltaics and Ferroelectrics
Robert L. Z. Hoye, Markus Hellenbrand, Nuno Estrócio et al. (+17 more)
The exponential, pervasive rise of artificial intelligence (AI), hosted in large data centres, will test the limits of the underpinning infrastructure, including electricity and water supplies, which are becoming increasingly precious resources. Rather than performing all AI computations in centralized servers, for many functionalities, these can be performed locally across a network of billions of small, autonomous nodes, saving substantial energy costs associated with communication. This alternative paradigm is known as edge computing, or distributed intelligence (DI), but has been held back by the lack of availability of reliable local energy supplies matching the energy requirements of the computational infrastructure. Opportunities to address this challenge are emerging with rapid advances in high-performance indoor photovoltaics (IPVs) for local energy harvesting, as well as reductions in computational cost through neuromorphic or in-
memory computing devices. In this perspective, we discuss the requirements of IPVs for DI, the extent to which emerging materials fulfil these requirements, and how current gaps could be addressed. We make the case that (anti)ferroelectric materials can surpass bottlenecks for both electrostatic energy storage and low-power in-
memory neuromorphic computing. The core theme of this perspective is that co-creation between energy harvesting, storage and computing is essential for making DI a reliable and more sustainable alternative to centralized AI.
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All authors Robert L. Z. Hoye, Markus Hellenbrand, Nuno Estrócio, Austin M. Kay, Alice Scardina, Alessandro Mezzetti, Ignasi Fina, Jorge Íñiguez-González, Luís S. Marques, Francesco Matteucci, Quanxi Jia, Judith L. MacManus-Driscoll, Bert Offrein, Florencio Sánchez, Beatriz Noheda, George Koutsourakis, Marina Freitag, Gregory Burwell, Giulia Grancini, Jose P. B. Silva
Mesoscale and Nanoscale Physics
Sven Bjarke Gudnason and Muneto Nitta
We perform an exhaustive study of the parameter space of the chiral
magnetic model with a Dzyaloshinskii-Moriya interaction, an in-plane anisotropy term and an out-of-plane Zeeman
magnetic field. We map out the phase diagram for the model and find a chiral
soliton lattice hosted on a chiral
soliton lattice as the ground state in a particular corner of the phase diagram. There is a smooth crossover, as opposed to a phase transition, to the skyrmion
crystal lattice phase. Finally, we also discover excited composite
soliton states such as an anti-skyrmion coexisting with a bimeron or an anti-bimeron.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Onset of a quantum Fisher-Selke sequence in the transverse-field ANNNI model and its bilayer
Tuan-Vu Truong, Vu-Quoc-Minh Nguyen, Hoang-Long Nguyen et al. (+1 more)
We study the transverse-field axial next-nearest-neighbor Ising (ANNNI) model on the square
lattice and on a bilayer. At the classical multiphase point $\kappa=J_2/J_0=1/2$, every configuration of straight domain walls that separates domains of at least two sites is a ground state. The walls are rigid, so perturbation theory in the transverse field $g=\Gamma/J_0$ can be carried out for each configuration separately, and we take it to order $g^8$.
Quantum fluctuations select $\langle 3\rangle$ ($\uparrow\uparrow\uparrow\downarrow\downarrow\downarrow$) at order $g^2$, because
spins next to a wall gain the most energy from virtual flips. The structures $\langle 23\rangle$, $\langle 223\rangle$ and $\langle 2223\rangle$ then open between $\langle 3\rangle$ and the antiphase $\langle 2\rangle$ at orders $g^4$, $g^6$ and $g^8$, in the order of the Fisher-Selke sequence of the classical three-dimensional model. A second layer suppresses each successive phase more strongly, beyond the stiffening of the local fields. We test the two widest phases with
stochastic series expansion
quantum Monte Carlo, comparing the free energies of the competing ordered states by thermodynamic integration, since annealing freezes in the modulation that forms at the ordering transition. The simulations reproduce the $\langle 3\rangle$ wedge to about 1%, and in a pre-registered test $\langle 23\rangle$ is stable at six of seven points, with the seventh resolved by post-hoc runs.
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All authors Tuan-Vu Truong, Vu-Quoc-Minh Nguyen, Hoang-Long Nguyen, Thanh-Tien Nguyen
Disordered Systems and Neural Networks
Ground-state properties of the two-dimensional SWAP spin-glass ensemble
Alexander K. Hartmann, Leticia F. Cugliandolo and Marco Tarzia
We study the recently introduced SWAP ensemble for Ising
spin-glasses, where the
spins obtain varying lengths, with length scale $\Delta \in [0, 2]$. The lengths can be exchanged in the spirit of the SWAP
algorithm for glassy poly-disperse hard-sphere systems. Using an annealing schedule, if the annealing is slow enough, ground states of the corresponding Ising
Hamiltonian, where the
spin lengths are incorporated into the bonds, can be obtained with high probability. We prove this statement for two-dimensional systems with sizes of up to $L^2=1024^2$
spins by comparison with exact ground states obtained by using graph matching
algorithms. In particular, we analyze the nature of the obtained realizations of the disorder by calculating exact zero-temperature domain-wall energies, from exact ground state calculations using periodic and anti-periodic boundary conditions. For medium or large values of $\Delta$, e.g. $\Delta=1$, the realizations turn ferromagnetic if the annealing is slow enough, i.e., they lose their zero-temperature
spin-glass property. If $\Delta$ is small, the realizations remain glassy, but the SWAP annealing does not easily find a true ground state.
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Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Deep learning enables large-scale inverse design of free-form metasurfaces
Viktor A. Lilja, Khosro Zangeneh Kamali, Mikael Käll et al. (+1 more)
Metasurfaces are ultrathin optical elements that control light through carefully engineered structures smaller than the wavelength of light, enabling compact devices with functionalities that are difficult to achieve with conventional optics. However, exploiting their full design freedom over large areas has been prohibited by the large computational cost of repeated electromagnetic simulations required for inverse design. Here we introduce a physics-tailored deep-learning surrogate model that exploits the locality and
symmetries of electromagnetic interactions to generalize from small-scale simulations to metasurfaces orders of magnitude larger. The model captures nonlocal interactions while predicting optical fields more than four orders of magnitude faster than the conventional electromagnetic solver it is trained on, enabling gradient-based
topology optimization under arbitrary illumination. We validate the approach through the inverse design and experimental realization of free-form metagratings with diffraction angles up to 75 degrees, as well as a millimeter-scale free-form holographic metasurface more than 1,000 wavelengths across and comprising 1.6 billion degrees of freedom. By decoupling the scale of electromagnetic simulation from the scale of inverse design, our approach enables system-scale free-form photonic devices that retain nanoscale design freedom.
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All authors Viktor A. Lilja, Khosro Zangeneh Kamali, Mikael Käll, Philippe Tassin
Mesoscale and Nanoscale Physics
Multi-bit Ferroelectric-NAND for High-throughput Massive Database Search
Prasanna Venkatesan, Tanvir H. Pantha, Po-Kai Hsu et al. (+28 more)
The growing demand for large-scale database search in data-intensive applications, ranging from proteomics to autonomous systems, has exposed fundamental limitations in von Neumann architectures due to
memory bandwidth and energy constraints. Hyperdimensional (HD) computing offers a robust and parallelizable framework for such tasks, but its practical implementation remains challenged by high
memory demands. Ultra-high-density, energy-efficient ferroelectric NAND (FE-NAND)
memory provides a potential solution by enabling in-situ computation. We fabricate quad-level FE-NAND strings with wide
memory windows, disturb resilience, and robust retention. Using these planar FE-NAND strings as building blocks, we experimentally demonstrate in-situ multi-level
cell (MLC) dot product operations at the single-
cell level and, using experimentally calibrated physics-based simulations, demonstrate Hamming similarity calculations between reference and query hypervectors (HV). This platform leverages the inherent error tolerance of HD computing to achieve >90% search accuracy even at high logic levels (TLC, QLC). When benchmarked on Open Modification Search (OMS) tasks in proteomics with TB-scale
datasets, our system shows nearly 1,000x speedup and over 10,000x energy efficiency improvement compared to incumbent solutions. These results establish FE-NAND as a viable in-storage compute architecture for large-scale, high-dimensional data processing.
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All authors Prasanna Venkatesan, Tanvir H. Pantha, Po-Kai Hsu, Sumukh Pinge, Zheyu Li, Chinsung Park, Priyankka Ravikumar, Hari Jayasankar, Lance Fernandes, Weihong Xu, Zihan Xia, Flavio Ponzina, Keming Fan, Amrit Garlapati, Huy Tran, Taeyoung Song, Mengkun Tian, Hang Chen, Winston Chern, Kijoon Kim, Kwangyou Seo, Suhwan Lim, Kwangsoo Kim, Wanki Kim, Daewon Ha, Duygu Kuzum, Shimeng Yu, Mingu Kang, Tajana Rosing, Sourav Dutta, Asif Khan
Mesoscale and Nanoscale Physics
Nonlinearity-induced Topological Phase Transitions in One-dimensional Systems with Chiral Symmetry: A Real-Space Treatment
Liu Bi Tao, Shilpi Roy and Jiangbin Gong
Nonlinearity can induce topological phase transitions in periodic systems. It is hence of considerable interest to examine if such transitions persist in the absence of translational
symmetry. We address this question directly in real space, using the periodic Su-Schrieffer-Heeger (SSH) chain as a reference for understanding the effect of quasiperiodicity. How nonlinearity drives a chain towards a topological phase transition is found to depend strongly on the strength of the quasiperiodic potential. As the nonlinearity strength increases, we find that weak quasiperiodicity supports a transition from a trivial to a topological phase, whereas the intermediate regime does not have a topological phase transition. Under strong quasiperiodicity, pronounced boundary localization can develop well before a nonlinearity-induced topological transition. Our results show how nonlinearity may interplay with a quasiperiodic potential in inducing topological phase transitions and that boundary localization of nonlinear eigenstates alone may not be taken as a clear signature of topological edge states.
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Strongly Correlated Electrons
Floquet dressing of bulk metallic bands in 2H-NbSe2
Cong Li, Qirui Cui, Maciej Dendzik et al. (+6 more)
Floquet dressing offers a route to controlling electronic states through periodic optical driving. Its realization in solids has centred primarily on topological-
insulator surface states,
semiconductors and two-dimensional Dirac semimetals. Extending this control to bulk metals would enable manipulation of the itinerant states underlying metallic transport and collective order. Yet strong screening and rapid scattering have long cast doubt on its feasibility in bulk metals, while photoelectron dressing complicates its identification. Here we identify Floquet dressing of the overlapping, bulk-derived metallic bands of 2H-NbSe2 using time- and angle-resolved photoemission spectroscopy.
Photon-shifted replicas in a sparse unoccupied-state window retain the parent-band dispersions and appear only during pump–probe overlap. Rotating the pump's linear polarization at fixed probe polarization redistributes replica weight between momentum-space branches. With a common parameter set, a model accounting for the optical fields inside and outside the solid captures this redistribution through coherent Floquet–Volkov interference more closely than either pathway alone or their incoherent intensity sum. These findings extend Floquet dressing to the itinerant bulk bands of a multiband metal without relying on the observation of energy gaps opened by hybridization between parent bands and their
photon-dressed replicas, providing a basis for exploring how coherent optical dressing couples to metallic transport and collective electronic phases.
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All authors Cong Li, Qirui Cui, Maciej Dendzik, Magnus H. Berntsen, Wanyu Chen, Zhilin Li, Anna Delin, Wentao Zhang, Oscar Tjernberg
Soft Condensed Matter
Effect of Added Salts on the Interfacial Dynamics of Monovalent Metal Ions and Model Water-Soluble Polymers
Soumik Ghosh, Jack F. Douglas and Francis W. Starr
Traditional theories of electrolyte and polyelectrolyte solutions overlook ion and
polymer hydration, yielding an overly idealized perspective of the thermodynamic and dynamic properties of these solutions. In particular, the propensity of certain ions to increase or decrease the water
diffusion coefficient at low solution concentrations, is poorly understood, a phenomenon that correlates strongly with the Hofmeister series describing the influence of salts on the solubility and self-assembly of synthetic and biomacromolecules as well as colloidal particles. These ion-specific effects have profound ramifications in diverse biological, medical science and technological applications. We address the general problem of understanding ion and uncharged water-soluble
polymer hydration through molecular dynamics (MD) simulations of representative water-soluble
polymers, polyacrylamide (PAM) and polyethylene oxide (PEO), in aqueous salt solutions. Careful
attention is given to the capacity of our model to reproduce observed trends of added monovalent salts on the
diffusion coefficient of water. Reproducing these ion-specific trends in the mobility of water has been a recurrent challenge in prior MD simulations of aqueous solutions based on a physically realistic model of water. Our work on salt solutions represents an important advance on which we build our modeling of aqueous
polymer solutions with added salts. Simulations of our model
polymers reveal an extended nanoscale dynamic hydration layer having a scale on the order of one nanometer (nm) in which the mobility is perturbed from its bulk value, and the mobility gradient in this layer appears to obey a near universal functional form.
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Soft Condensed Matter
Effect of Temperature and Added Salt on a Model Polyzwitterion Polymer in Dilute Solution
Soumik Ghosh, Vivek M. Prabhu and Jack F. Douglas
The competitive interactions arising from the proximity of positive and negatively charged groups in the monomers in polyzwitterions (PZ) makes these
polymers have properties similar in some ways to intrinsically disordered
proteins. To gain qualitative insights into this important class of water-soluble
polymers, we performed molecular dynamics (MD) simulations of a model PZ chain with an explicit solvent to understand the conformational state in the absence and presence of added salt. We find that isolated PZ chains under salt-free conditions adopt a self-associated state having a weak dependence on temperature. The addition of an appreciable amount of NaCl leads to a weakening of the intrachain associations, resulting in chain expansion, a transition reminiscent of the denaturation of globular
proteins. In particular, the hydrodynamic penetration function, the ratio of hydrodynamic radius to the radius of gyration, of the PZ chains under salt free conditions, is found to be more consistent with a randomly branched
polymer or single chain nanoparticle than a random coil
polymer where the physical cross-links within the chain arise from the dipoles within the chain. The chain conformation not only tends to become larger with the addition of salt but also acquires a more appreciable temperature dependence of its average size with temperature. This swelling trend of PZ molecules with added salt, sometimes referred to as the anti-polyelectrolyte effect, is distinct from the normal trend polyelectrolytes, which typically become more contracted with the addition of salt. We also examined the spatial extent of the dynamic hydration layer the PZ chain, both with and without added salt, and the effect of temperature and salt concentration on the water mobility within this layer, and PZ side-chain mobility, whose dynamics is apparently strongly coupled to the surrounding water molecules.
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Materials Science
Anisotropic mesoscale magnetic scattering across the spin-reorientation transition in TbMn6Sn6
Zhuang Xu, Fan Chen, Hui Cheng et al. (+10 more)
TbMn6Sn6 is a centrosymmetric ferrimagnetic kagome metal that combines topological electronic states with strong
magnetic anisotropy and a near-room-temperature
spin-reorientation transition (SRT). Real-space imaging studies of thin specimens have revealed helical stripes, biskyrmion-like textures, and skyrmion-bubble-like structures in the
spin-reorientation regime. Whether such local textures develop into a bulk long-range-ordered skyrmion
lattice remains unresolved. Here we present small-angle
neutron scattering (SANS) results probing the mesoscale magnetism of a bulk TbMn6Sn6 single
crystal. We observe no sixfold SANS Bragg pattern indicative of a long-range-ordered skyrmion
lattice under the explored conditions. Instead, the dominant
magnetic response is an anisotropic twofold low-Q scattering component whose intensity distribution and field dependence evolve markedly across the
spin-reorientation regime. In zero field, a broad and horizontally elongated low-Q signal develops above TSR and weakens as the system approaches the paramagnetic state. At 345 K with H || b, the signal is diffuse and is suppressed rapidly below about 700 Oe. By contrast, at 310 K with H || c, close to TSR, the response is more concentrated and line-shaped and persists to higher fields. The contrasts between these scans likely reflect the combined effects of rapidly evolving
magnetic anisotropy near TSR and the field geometry. Our results therefore establish a bulk anisotropic mesoscale
magnetic response across the
spin-reorientation regime, consistent with stripe- or domain-related textures reported by real-space imaging, while not uniquely identifying their real-space morphology.
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All authors Zhuang Xu, Fan Chen, Hui Cheng, Xinmin Wang, Taisen Zuo, He Cheng, Haitao Hu, Cuiping Zhang, Qian Zhao, Michel Kenzelmann, Jonathan S. White, Junying Shen, Xin Tong
Materials Science
Identification and Structural Decomposition of Hidden Defect Configurations: A Case Study of Charged Oxygen Divacancies in HfO$_2$
Hyunjin Lee, Yoon Kyeung Lee, Keun Heo et al. (+2 more)
Extensive configurational searches have revealed hidden defect structures in crystalline compounds, yet how their local bonding arrangements modify the surrounding atomic environment remains less well understood. We examine this question in hafnium oxide (HfO$_2$), which hosts energetically competing monoclinic (M), tetragonal (T), and polar orthorhombic (PO) polymorphs. For the $c$-axis oxygen-divacancy complex ($T_c$), a local-distortion search with density-functional theory (DFT) relaxation under tetragonal-
lattice confinement identifies a hidden family of low-energy configurations ($T_c^{*}$). For the fully charged complex ($2\mathrm{V}_{\mathrm{O}}^{2+}$), structural decomposition using Smooth Overlap of Atomic Positions (SOAP) descriptors reveals mixed M-, T-, and PO-like character, supported by independent analyses of Hf coordination and bond geometry. The idealized $T_c$ reference connects barrierlessly to the lowest-energy mixed-motif $T_c^{*}$ configuration, lowering the energy by $18.4$ meV/f.u. within the confined landscape. After releasing the
lattice constraint, we compare transformation pathways to M and PO using solid-state nudged elastic band calculations with
cell-relaxed endpoints. The respective barriers increase from $6.9$ and $10.1$ meV/f.u. for the idealized reference to $26.9$ and $15.3$ meV/f.u. for the $T_c^{*}$-derived structure. The larger increase for M makes PO, rather than M, the lower-barrier branch. This case study shows how structural decomposition connects hidden defect configurations with changes in the surrounding atomic environment and kinetic branching between competing polymorphs.
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All authors Hyunjin Lee, Yoon Kyeung Lee, Keun Heo, Shi Liu, Taehun Lee
Materials Science
Phenomenon-first problem formulation with language models in metal-organic frameworks
Jihan Kim
Here we introduce a phenomenon-first framework for materials discovery in which an LLM receives separate descriptions of guest physics, host capabilities and operating context and proposes an unusual qualitative behavior with its mechanism, distinguishing signature and falsifier. Across 80 guest-host combinations in metal-organic frameworks, the model generated 57 proposals that were frozen before evaluation or materials selection; assessment identified nine computationally tractable candidates. In a repeat and guest-only baseline, structured formulation reproducibly broadened mechanistic exploration: the original and repeat runs each covered 21 broad mechanism families versus eight for guest-only formulation despite fewer proposals. From the original run, MC-010 yielded reproducible hydration-driven reorientation of retained ethanol in experimentally reported MOFs, while MC-015 yielded a
quantum-corrected reversal of H$_2$ adsorption-region preference relative to the matched classical description. These results show how structured LLM
reasoning can move upstream from executing supplied objectives toward prospectively formulating qualitative materials phenomena.
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Superconductivity
Superconducting landscape of the strongly correlated bilayer Hubbard model
Motoharu Kitatani, Yusuke Nomura, Shiro Sakai et al. (+1 more)
Coupling two strongly correlated layers opens a distinct route to repulsion-driven superconductivity. Yet the same interlayer coupling makes the optimization of superconductivity highly nontrivial. Using the dynamical vertex approximation, we determine the superconducting landscape in the enlarged parameter space spanned by filling and interlayer hopping. We identify an optimal regime at intermediate interlayer hopping and moderate doping away from half filling, where the system exhibits high superconducting transition temperatures ($T_{\rm c}$) with an interband $s_{\pm}$-wave gap structure. Toward half filling, however, strong self-energy effects can suppress the superconducting tendency by reducing the low-energy spectral weight. We further show that a Fermi-surface distortion induced by longer-range hoppings can weaken this suppression and enhance $T_{\rm c}$. Our results establish how filling, interlayer hopping, and Fermi-surface geometry jointly optimize the superconducting regime in the strongly correlated bilayer Hubbard model.
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All authors Motoharu Kitatani, Yusuke Nomura, Shiro Sakai, Ryotaro Arita
Statistical Mechanics
Multicatalyst reactions induce abrupt transition in a dense catalytic reaction network model
Kota Mitsumoto and Shuji Ishihara
We generalize the Furusawa–Kaneko model, a simple model of intracellular catalytic reaction networks, to multicatalyst reactions and analyze the generalized model using dynamical mean-field theory. In the thermodynamic and dense-network limit, we derive exact effective equations and analyze their fixed points for arbitrary degree distributions. Under nutrient-poor conditions, network heterogeneity suppresses the metabolic–starvation transition irrespective of the number of catalysts per reaction. In contrast, under nutrient-rich conditions, the bifurcation structure changes with the number of catalysts. With one catalyst per reaction, only continuous transitions occur, whereas two or more catalysts give rise to bistable phases and discontinuous transitions. The bifurcation structure also differs between two and three catalysts per reaction, with three catalysts allowing bistability between metabolic states with different
cell growth rates. Our results provide a possible mechanism for bistability and abrupt switching in metabolic dynamics.
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Quantum Gases · Cross-listed from physics.flu-dyn
Landau damping and mode-selective instability of a vortex gas
H. Terças, J. L. Figueiredo, J. T et al. (+1 more)
We show that a collisionless point-
vortex gas behaves as a genuine Vlasov system. Starting from the non-canonical
Hamiltonian structure of point-
vortex dynamics, we derive a reduced Klimontovich equation and the corresponding Vlasov description directly on the physical plane, without introducing auxiliary momentum variables. The theory predicts a rich spectrum of collective phenomena, including
vortex Rossby-like waves, global oscillations, resonant critical layers, and a dielectric response operator analogous to that of
plasmas and self-gravitating systems. For smooth
vortex distributions, differential rotation gives rise to a
vortex analogue of Landau damping, whereby collective modes transfer energy and angular momentum to resonant
vortex annuli in the absence of collisions or dissipation. Remarkably, differential rotation acts as a stringent mode-selection mechanism: for a Gaussian
vortex cloud, only a single quadrupolar quasi-mode survives, while all higher multipoles are destroyed by phase mixing. We further predict a
vortex counterpart of the beam–
plasma instability, in which a thin
vortex ring orbiting an Onsager patch selectively excites Kelvin modes with an azimuthal
symmetry controlled by the ring population. These results establish kinetic theory as a natural framework for collective
vortex dynamics and suggest new mechanisms for
vortex transport,
vortex avalanches, and rotational glitches in
neutron-
star superfluids.
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All authors H. Terças, J. L. Figueiredo, J. T, Mendonça
Superconductivity · Cross-listed from quant-ph
Epitaxial NbN-junction-based self-shunted superconducting flux qubit with high anharmonicity
Tokunoshin Uchida, Shingo Nozaki, Daiki Kurihara et al. (+5 more)
We report a demonstration of a self-shunted superconducting flux
qubit (SSFQ) as an ultracompact, strongly anharmonic, and long-lifetime
qubit by using the full epitaxially grown NbN/AlN/NbN Josephson junctions. The NbN-junction-based SSFQ achieved a high anharmonicity of 797 MHz as well as drastically reduced footprint of the
qubit compared to capacitively shunted (C-shunt) flux
qubits with a large shunt capacitor. The lifetime of the SSFQ reached 13 - 25 $\mu$s, which is comparable to or relatively higher than that of NbN-based C-shunt flux
qubits and Al-based flux
qubits with more than 10 times smaller junctions. This indicates that the large epitaxial NbN-based junction can be adopted for SSFQ as well as merged-element transmon with the relatively large junctions. The results presented in this work will offer a new choice of the scalable
qubits as well as the material platform toward the realization of large-scale superconducting
quantum computers.
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All authors Tokunoshin Uchida, Shingo Nozaki, Daiki Kurihara, Hiroki Kutsuma, Shotaro Shirai, Atsushi Noguchi, Hirotaka Terai, Taro Yamashita