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Physics Condensed Matter

cond-mat Watch Condensed Matter

Wednesday 15 July

Mesoscale and Nanoscale Physics

On-chip quantum sensing of Kondo spins in a high-mobility quasi-one-dimensional nanoconstriction

Shun-Tsung Lo, Che-Cheng Wang, Sheng-Chin Ho et al. (+15 more)

The precise nature of Kondo spins has remained enigmatic when extended to multiple spin impurities or, more intriguingly, when the localized spin itself may already be the consequence of many-body interactions in a presumably-delocalized open nanoconstriction, such as a quantum point contact (QPC). It is experimentally challenging to distinguish the Kondo state from other coexisting many-body spin states in such a strongly correlated system. Here we lithographically define an all-on-chip electronic resonator (ER) and a QPC in a high-mobility GaAs/AlGaAs heterostructure transistor. Local Kondo screening of the QPC spin and nonlocal spin singlet across the ER-QPC integration are controllable in response to ER occupancy parity. We also show that the 0.7 anomaly, another strongly-correlated state in QPCs, not only has a different physical origin but furthermore counteracts the Kondo spin singlet. These results demonstrate a noninvasive quantum method for sensing spontaneous magnetic impurities within an open nanoconstriction.
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All authors Shun-Tsung Lo, Che-Cheng Wang, Sheng-Chin Ho, Jun-Hao Chang, Ming-Wei Chen, G. L. Creeth, L. W. Smith, Shih-Hsiang Chao, Yu-Chiang Hsieh, Pei-Tzu Wu, Yi-Cheng Wu, Chi-Te Liang, M. Pepper, J. P. Griffiths, I. Farrer, G. A. C. Jones, D. A. Ritchie, Tse-Ming Chen

Statistical Mechanics

The nonequilibrium statistical mechanics of Markov interacting particles

Dalton A R Sakthivadivel

We consider coupled stochastic systems decomposed into exterior, boundary, and interior variables, with the boundary variables sometimes carrying the directed structure of a sensor and actuator. The central question is when the conditional law of histories factorises, and how this path space statement is detected by log likelihoods, by Girsanov changes of measure, and by information theoretic quantities used in nonequilibrium statistical physics. The basic object is a regular conditional probability on a path space. Under domination by clamped reference laws, the boundary property becomes multiplicative separation of a Radon–Nikodym derivative, or equivalently additive separation of a path log likelihood. For Itō diffusions this log likelihood is computed by Girsanov's theorem; its expectation is the quadratic control energy appearing in the Föllmer entropy identity and in the stochastic control formulation of Schrödinger bridge problems. When exact factorisation fails, the remaining coupling is measured by conditional mutual information, namely the relative entropy between the true boundary-conditioned path law and the product of its conditional marginals. This gives a common language for boundary screening, path likelihood inference, controlled changes of path law, and the thermodynamic value of mutual information.
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Statistical Mechanics

A Loewner-Theoretic Approach to the Nonlinear Generalized Langevin Equation: The Role of Entropy in Colored Noise Environment

Yusuke K. Shibasaki

In this study, the formal derivation of a one-dimensional nonlinear generalized Langevin equation is demonstrated using a decomposition method based on the conformal transformation governed by the chordal Loewner equation. Here, we used a modified Mori-Zwanzig method whose operator is substituted by that is derived from the discrete Loewner evolution. By this approach, the different types of fluctuation-dissipation relation (FDR) were reformulated using mathematical terms affected by the conformal maps. Dealing with a memory kernel that models the cell migration experiment, the numerical simulation was performed to obtain the specific scaling law of energy dissipation that is common among the two obtained types of FDRs. In addition, the concept of Loewner entropy is used for the estimation of the canonical ensemble in the colored noise environment throughout the theoretical analyses.
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Strongly Correlated Electrons

The Sample Pre-selection and Characterization Station at the SECUF: Instrumentation, Capabilities, and Representative Scientific Achievements

Xu Chen, Tao Sun, Huifen Ren et al. (+4 more)

The Synergetic Extreme Condition User Facility (SECUF) is a comprehensive, state-of-the-art user facility designed to provide integrated extreme physical conditions-including ultrahigh pressure, ultralow temperature, strong magnetic fields, and ultrafast optical fields-for frontier research in condensed matter physics and materials science. Within SECUF, the F2 Sample Pre-selection and Characterization Station plays a pivotal supporting role. Its mission is to provide comprehensive sample synthesis, processing, pre-screening, and characterization services to prepare high-quality specimens for subsequent experiments under extreme conditions. This paper details the specifications and performance of ten core instrument systems within these units. Furthermore, we highlight several breakthrough scientific achievements enabled by the F2 Station, encompassing the discovery of novel quantum spin supersolid states, pressure-induced high-temperature superconductivity in nickelates, giant anomalous Hall angles, and molecular water in lunar soil. We also outline ongoing technical developments that expand the station's capabilities, such as integrated high-pressure cells and self-built ancillary measurement systems.
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All authors Xu Chen, Tao Sun, Huifen Ren, Minjie Cui, Jun Luo, Shuai Zhang, Shaokui Su

Materials Science

Direct Imaging of Temperature Evolution of Polar Nanoregions and Chemically Ordered Regions in PMN Relaxor: Evidence for Polar Phase Percolation

Kohei Hino, Daisuke Morikawa, Desheng Fu et al. (+2 more)

Polar nanoregions (PNRs) are central to understanding the exceptional dielectric and piezoelectric properties of relaxor ferroelectrics and are key to advancing dielectrics for high-energy storage. However, direct real-space imaging of their formation and evolution remains a major challenge in condensed matter physics. Here, we report the real-space mappings of both PNRs and chemically ordered regions (CORs) in the prototypical relaxor Pb(Mg1/3Nb2/3)O3 and their temperature dependence using convergent-beam electron diffraction (CBED) combined with four-dimensional scanning transmission electron microscopy (4D-STEM). The results reveal that CORs, with sizes of 2-5 nm, remain static with temperature and act to suppress PNR growth. In contrast, PNRs evolve from isolated 2-5 nm regions at room temperature to interconnected structures ~10 nm in size at low temperatures, indicative of a percolation transition. These observations support the random-field model, in which PNRs emerge from a paraelectric matrix and their growth and collective interactions are constrained by random local fields associated with CORs.
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All authors Kohei Hino, Daisuke Morikawa, Desheng Fu, Mitsuru Itoh, Kenji Tsuda

Tuesday 14 July

Statistical Mechanics

Gaussian Reformulation of the Feynman Path Integral for Quantum Statistical Mechanics with Results for the Second Virial Coefficient of $^4$He

Phil Attard

The Feynman path integral for quantum statistical mechanics is reformulated as Gaussian sampling of the neighborhood of each position configuration. The variance and mean are obtained from ring polymer statistics on a lattice, and from the high temperature expansion of the Wigner-Kirkwood commutation function, respectively. The algorithm avoids multiple temperature nodes for each configuration and the need for numerical cancelation in the statistical averages, which are problematic for conventional path integral quantum Monte Carlo. Analytic and simulation results for the second virial coefficient of helium are compared to laboratory measurements.
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Soft Condensed Matter · Cross-listed from physics.bio-ph

Robust topological oscillators govern a tunable phase transition to synchronized circadian rhythms

Chongbin Zheng, Peter Thomas and Evelyn Tang

While synchronization has been well-studied in deterministic oscillators, most underlying oscillators are stochastic in both natural and man-made systems. Yet, the effects of intrinsic stochasticity remain poorly understood. Here, we develop a new mechanism for synchronizing circadian KaiC molecules that have topologically protected cycles. We find a phase transition to synchronization that depends only on the single-oscillator coherence, across a range of molecular changes that determine this coherence. Examining both mesoscopic and macroscopic numbers relevant for cellular and in vitro conditions respectively, we find different scaling properties above and below the phase transition. Our results shed light on several existing experiments and further predict that external changes can be offset by compensatory changes that improve the single-oscillator coherence - demonstrating a tunable pathway between stochastic single oscillators and their robust collective rhythms.
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Soft Condensed Matter

Fundamental Relation between Conductance of Biomolecules and the Fukui Function

Gabor Vattay

The finite-temperature conductance of a molecule coupled to metallic leads is derived entirely within the framework of density functional theory (DFT) and its time-dependent extension for open quantum systems. Starting from the Mermin grand potential, the foundational Kohn-Sham equations, the Fukui function, and the open-system master equation for the single-particle density matrix are systematically formulated. The non-equilibrium electron-phonon dissipator is obtained from the partial trace over the phonon bath. By applying Wick's theorem for non-interacting fermions, a fully exchange-symmetric collision integral is obtained that strictly preserves Pauli exclusion at the operator level. Performing a double perturbation expansion, initially in the applied voltage (linear response), and subsequently in the molecule-lead coupling (weak coupling), it is demonstrated that under the fast-thermalization condition, the complex exchange-correlation self-consistent field response is analytically projected out by the diagonal structure of the slow Liouvillian mode. Consequently, the thermal conductance is governed by the finite-temperature Fukui function, the central reactivity descriptor of conceptual density functional theory. This condition is satisfied in proteins, whose wave functions are extended and multifractal due to quantum criticality at the Anderson metal-insulator transition. This derivation establishes a fundamental link between electronic transport and chemical reactivity, identifying conducting paths with reactive sites. It opens new technological avenues connecting drug design to conductance experiments and also provides a foundation for designing next-generation bioelectronic sensing and computing architectures.
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Mesoscale and Nanoscale Physics · Cross-listed from quant-ph

Precision quantum simulation of magnon spectra and interactions

Trond I. Andersen, Nikita Astrakhantsev, Jeronimo Martinez et al. (+329 more)

Quantum simulation promises to advance materials discovery by accurately simulating complex states of matter, their microscopic excitations, and macroscopic response functions. The central challenge in resolving the underlying interacting dynamics is to combine high-fidelity evolution with the sophisticated control necessary to manipulate individual quasi-particles in quantum many-body states. Here, we report on high-precision simulation of both linear and non-linear response functions in a 2D XY spin-1/2 magnet using an analog-digital superconducting processor of up to 97 qubits. By interleaving digital gates with analog evolution precisely characterized via Hamiltonian learning, we selectively excite magnons at tunable energy densities. Measuring first the linear magnon response – a central probe in neutron-scattering experiments – we extract temperature-dependent spectra and lifetimes. Our results reveal stark variations in magnon decay rates across the Brillouin zone, with enhancement near van Hove singularities and suppression for edge-localized modes. Next, we perform a suite of nonlinear measurements, including the study of self-scattering mechanisms, as well as pump-probe spectroscopy to directly characterize the magnon interactions. While matrix-product state simulations capture the dynamics well in either small systems or at low temperatures, their predictions become inaccurate away from these limits. This work demonstrates precise simulation of the interacting dynamics in quantum magnets, and provides key insights into quasi-particles and their microscopic scattering mechanisms.
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All authors Trond I. Andersen, Nikita Astrakhantsev, Jeronimo Martinez, Will Morong, Johannes Motruk, Dario Rossi, Brayden Ware, Bryce Kobrin, Weijie Wu, Elizabeth Bennewitz, Manuel Rudolph, Tom Westerhout, Amira Abbas, Rajeev Acharya, Laleh Aghababaie Beni, Ross Alcaraz, Sayra Alcaraz, Markus Ansmann, Frank Arute, Kunal Arya, Walt Askew, Juan Atalaya, Christopher Ayala, Ryan Babbush, Brian Ballard, Joseph Bardin, Hector Bates, Andreas Bengtsson, Majid Bigdeli Karimi, Alexander Bilmes, Simon Bilodeau, Felix Borjans, Alexandre Bourassa, Jenna Bovaird, Dylan Bowers, Leon Brill, Peter Brooks, Michael Broughton, David Browne, Brett Buchea, Bob Buckley, Tim Burger, Brian Burkett, Jamal Busnaina, Nicholas Bushnell, Jonas Bylander, Anthony Cabrera, Juan Campero, Hung-Shen Chang, Silas Chen, Zijun Chen, Ben Chiaro, Liang-Ying Chih, Agnetta Cleland, Bryan Cochrane, Matt Cockrell, Josh Cogan, Paul Conner, Tom Connolly, Harold Cook, Rodrigo Cortinas, William Courtney, Alexander Crook, Benjamin Curtin, Adam Dally, Sayan Das, Martin Damyanov, Dripto Debroy, Himadri Dey, Stijn de Graaf, Laura De Lorenzo, Sean Demura, Lucia De Rose, Agustin Di Paolo, Leon Ding, Howard Dobbs, Paul Donohoe, Ebru Dogan, Ilya Drozdov, Andrew Dunsworth, Rasmus Edholm, Valerie Ehimhen, Alec Eickbusch, Aviv Elbag, Lior Ella, Mahmoud Elzouka, David Enriquez, Catherine Erickson, Lara Faoro, Vinicius Ferreira, Marcos Flores, Leslie Flores Burgos, Sam Fontes, Ebrahim Forati, Jeremiah Ford, Brooks Foxen, Masaya Fukami, Alan Fung, Lenny Fuste, Suhas Ganjam, Gonzalo Garcia, Christopher Garrick, Robert Gasca, Helge Gehring, Robert Geiger, Élie Genois, William Giang, Dar Gilboa, James Goeders, Edward Gonzales, Raja Gosula, Alejandro Grajales Dau, Dietrich Graumann, Joel Grebel, Alex Greene, Jonathan Gross, Jose Guerrero, Tan Ha., Steve Habegger, Tanner Hadick, Ali Hadjikhani, Michael Hamilton, Monica Hansen, Matthew Harrigan, Sean Harrington, Jeanne Hartshorn, Stephen Heslin, Paula Heu, Oscar Higgott, Reno Hiltermann, Jeremy Hilton, Hsin-Yuan Huang, Michael Hucka, Christopher Hudspeth, Ashley Huff, William Huggins, Aditya Jayaraman, Evan Jeffrey, Shaun Jevons, Zhang Jiang, Xiaoxuan Jin, Cody Jones, Chaitali Joshi, Kelsey Josund, Pavol Juhas, Andreas Kabel, Bharath Kannan, Hui Kang, Kiseo Kang, Amir Karamlou, Ryan Kaufman, Tanuj Khattar, Mostafa Khezri, Seon Kim, Paul Klimov, Can Knaut, Alexander Korotkov, Fedor Kostritsa, John Mark Kreikebaum, Ryuho Kudo, Arun Kumar, Ben Kueffler, Vladislav Kurilovich, Vitali Kutsko, Nathan Lacroix, Tiano Lange-Dei, Brandon Langley, Pavel Laptev, Kim-Ming Lau, Emma Leavell, Loïck Le Guevel, Justin Ledford, Joy Lee, Kenny Lee, Brian Lester, Wendy Leung, Matthew Lloyd, Lily Li, Wing Li, Ming Li, Alexander Lill, Mike Lindmark, William Livingston, Aditya Locharla, Erik Lucero, Daniel Lundahl, Aaron Lunt, Sid Madhuk, Donald Macaskill, Aniket Maiti, Ashley Maloney, Salvatore Mandra, Leigh Martin, Orion Martin, Eric Mascot, Paul Masih Das, Anselme Massimino, Melvin Mathews, Cameron Maxfield, Jarrod McClean, Matthew McEwen, Seneca Meeks, Anthony Megrant, Tim Menke, Kevin Miao, Zlatko Minev, Reza Molavi, Sebastian Molina, Shirin Montazeri, Akira Nakamura, Charles Neill, Konstantin Nesterov, Michael Newman, Roselle Ngaloy, Anthony Nguyen, Murray Nguyen, Chia-Hung Ni, Murphy Niu, Nicholas Noll, Sergey Novikov, Logan Oas, Ricky Oliver, Will Oliver, Raymond Orosco, Kristoffer Ottosson, Alice Pagano, Manan Patel, Sherman Peek, David Peterson, Alex Pizzuto, Thomas Plumb-Reyes, Elias Portoles, Rebecca Potter, Orion Pritchard, Sam Probst, Michael Qian, Chris Quintana, Matthew Rakher, Arpit Ranadive, Ganesh Ramachandran, Armin Razavi, Matthew Reagor, Rachel Resnick, David Rhodes, Daniel Riley, Gabrielle Roberts, Roberto Rodriguez, Emma Ropes, Eliott Rosenberg, Emma Rosenfeld, Dario Rosenstock, Elizabeth Rossi, Pedram Roushan, David Rower, Robert Salazar, Kannan Sankaragomathi, Murat Sarihan, Kevin Satzinger, Max Schaefer, Sebastian Schroeder, Henry Schurkus, Aria Shahingohar, Michael Shearn, Aaron Shorter, Shvarts Vladimir, Vlad Sivak, Spencer Small, W. Clarke Smith, David Sobel, Barrett Spells, Sofia Springer, George Sterling, Scott Stonemeyer, John Su, Jordan Suchard, Youngkyu Sung, Aaron Szasz, Alex Sztein, Tomoyuki Tanaka, Madeline Taylor, Jothi Thiruraman, Douglas Thor, Brandur Thorgrimsson, Dogan Timucin, Eifu Tomita, Alfredo Torres, M. Mert Torunbalci, Hao Tran, Abeer Vaishnav, Justin Vargas, Gopinath Vasalamarri, Sergey Vdovichev, Guifre Vidal, Benjamin Villalonga, Meghan Voorhees, Steven Waltman, Jonathan Waltz, Shannon Wang, Danni Wang, James Watson, Yonghua Wei, Travis Weidel, Theodore White, Kristi Wong, Bryan Woo, Christopher Wood, Maddy Woodson, Cheng Xing, Z. Jamie Yao, Ping Yeh, Bicheng Ying, Juhwan Yoo, Noureldin Yosri, Elliot Young, Grayson Young, Adam Zalcman, Ran Zhang, Yaxing Zhang, Yiqing Zhou, Ningfeng Zhu, Nicholas Zobrist, Zhenjie Zou, Sergio Boixo, Yu Chen, Julian Kelly, Hartmut Neven, Vadim Smelyanskiy, Dvir Kafri, L. B. Ioffe, Kostyantyn Kechedzhi, Xiao Mi, Dmitry Abanin

Superconductivity

Theoretical prediction of structural stability and superconductivity in T-hexagonal molybdenum dihydrides Monolayer

Jakkapat Seeyangnok and Udomsilp Pinsook

The realization of ambient-pressure, high-temperature superconductivity in hydrogen-rich materials remains a major pursuit in condensed-matter physics. While bulk hydrides require extreme pressures to stabilize, two-dimensional (2D) transition-metal hydrides offer a promising alternative to bypass these compression constraints. In this work, we investigate the structural stability, electronic properties, and phonon-mediated superconductivity of a hexagonal molybdenum dihydride (MoH2) monolayer using first-principles calculations. Total-energy evaluations reveal that the octahedral T-phase is energetically more favorable than the previously reported trigonal prismatic H-phase by 0.198 eV, establishing the T-phase as the true ground-state configuration. Consequently, we systematically evaluate the lattice dynamics and superconducting properties of this ground-state T-MoH2 monolayer within the frameworks of density functional perturbation theory (DFPT) and the anisotropic Migdal-Eliashberg formalism. The transition metal-hydrogen vibrational networks induce strong electron-phonon coupling (EPC), yielding an integrated coupling parameter of \lambda = 1.04. Solving the anisotropic Eliashberg equations predicts a conventional superconducting transition temperature (Tc of 14.4K) at ambient pressure, characterized by a moderately gap distribution (\Delta = 2.07-3.01meV at 5.0 K). Our findings highlight the T-MoH2 monolayer as a structurally, mechanically, and thermally stable platform for exploring low-dimensional conventional superconductivity under ambient conditions.
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Mesoscale and Nanoscale Physics

Electronic properties and topological aspects of graphene nanohelicoids

Xiaoqian Liu, Arsen Herasymchuk, Yaroslav Zhumagulov et al. (+1 more)

We introduce graphene nanohelicoids, geometric analogs of graphene nanoribbons, in which the honeycomb lattice is embedded on a helicoidal surface. Starting from the three-dimensional helical structure, we construct effective one-dimensional lattice models with band structures characterized by a momentum-shifted particle-hole relation $E_v(k)=-E_c(k+\pi)$ that reflects an antichiral symmetry arising from the nonsymmorphic symmetry. A systematic investigation of graphene nanohelicoids using the tight-binding approximation reveals a number of trends upon varying width and edge orientation, for instance, alternating transitions between semiconducting and metallic regimes. As the structure width varies, the band gap periodically closes and reopens, accompanied by an alternating Zak phase that switches between trivial and nontrivial. Using an analytic tight-binding model with a continuous deformation of the graphene nanohelicoids, we explain the origin of width- and termination-dependent band inversion and alternating Zak phase, and derive the relationship between the termination-resolved index and the sublattice symmetry operator in one-dimensional nonsymmorphic systems.
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All authors Xiaoqian Liu, Arsen Herasymchuk, Yaroslav Zhumagulov, Oleg V. Yazyev

Soft Condensed Matter

Modeling damage and fracture in additively manufactured polymeric triply periodic minimal surface lattices

Abhishek Gupta, Aditya Konale, Ke Ma et al. (+4 more)

Architected triply periodic minimal surface (TPMS) lattices offer superior specific energy absorption, toughness, fatigue strength, and tunability. While recent advancements have established rate-dependent viscoplastic constitutive models to capture the complex nonlinear deformation response of additively manufactured polymeric TPMS structures, predicting fracture and the resulting structural failure remains a significant challenge. We address this by performing systematic experiments on unit cells and lattices of various sizes under tension, compression, and non-monotonic loading. The experiments inform the development of a new constitutive model that captures the damage and fracture behavior of polymeric TPMS lattices. We first implement a high-fidelity viscoplastic deformation constitutive model from Ma et al. (2026) into finite element software Abaqus/Explicit via a user material subroutine. We then propose a damage initiation criterion for amorphous polymers based on stored elastic energy and equivalent plastic strain. The damage model is implemented in Abaqus using gradient-damage framework following Konale and Srivastava(2025). The damage model and numerical simulation capability are quantitatively and qualitatively validated using experimental results for a unit cell under non-monotonic loading and lattices under tension. The proposed damage model and simulation capability enable in silico design of architected polymer structures.
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All authors Abhishek Gupta, Aditya Konale, Ke Ma, Keven Alkhoury, Pradeep Guduru, Yuri Bazilevs, Vikas Srivastava

Statistical Mechanics

Exact collective first-passage statistics of N trail-interacting walkers

Paul Pineau, Julien Brémont, Olivier Bénichou et al. (+1 more)

Memory encoded in the environment mediates interactions between active agents, from trail-following organisms to synthetic active matter depositing persistent tracks. Although such memory is known to strongly affect transport, its consequences for collective first-passage phenomena remain largely unexplored. Here we study $N$ one-dimensional random walkers interacting through a shared trail field. We characterize the $k^{\rm th}$ (among $N$) arrival time at a fixed target, and the probability that exactly $k$ walkers in $[0,1]$ reach one boundary before the other. For the broad class of self-interacting walkers with a saturating response to the trail, we derive exact expressions for the corresponding persistence exponents and splitting probabilities. Strikingly, despite the strong history-dependent correlations generated by the common environment, splitting probabilities are exactly identical whether walkers explore simultaneously or one after another. This invariance breaks down for nonsaturating trail interactions. Our results follow from an exact representation of the collective trail field and establish a framework for first-passage phenomena in systems coupled through persistent environmental memory.
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All authors Paul Pineau, Julien Brémont, Olivier Bénichou, Raphaël Voituriez

Materials Science

Multiwavelength Raman investigation of mono- and few-layer MoS2 grown by Pulsed Laser Deposition on SiO2

Alice Cartoceti, Paolo D'Agosta, Francesco Tumino et al. (+3 more)

Molybdenum disulfide (MoS$_2$) is a semiconductor whose vibrational and excitonic properties are highly sensitive to layer number and structural disorder. We demonstrate the growth of MoS$_2$ monolayers on inert, electronics-compatible SiO$_2$ substrates using room-temperature pulsed laser deposition (PLD). Control of the process parameters enables tuning from monolayer to multilayer films, which we investigate by multiwavelength Raman spectroscopy. The evolution of the Raman-shift difference between the $E_{2g}^{1}$ and $A_{1g}$ modes, combined with an assessment of defect density, tracks film growth as a function of the number of deposition laser pulses. Although excitonic effects strongly influence the optical response of two-dimensional transition-metal dichalcogenides, experimental reports of symmetry-selective exciton-phonon coupling remain limited. We provide experimental evidence of symmetry-dependent exciton-phonon coupling in PLD-grown monolayer MoS$_2$. Specifically, we observe modulation of the resonant behaviour of the out-of-plane $A_{1g}$ and in-plane $E_{2g}^{1}$ modes, related to their different coupling to A excitons, predominantly derived from Mo $d_{z^2}$ orbitals, and C excitons, characterized by mixed orbital contributions from Mo $d_{z^2}$ and S $p_x$ and $p_y$ states. Comparison with mechanically exfoliated monolayers reveals the role of growth-induced defects in modulating these interactions. These findings establish room-temperature PLD as a viable approach for growing two-dimensional MoS$_2$ on inert, electronics-compatible substrates and provide insight into the interplay between excitonic resonances and growth-induced disorder in two-dimensional MoS$_2$.
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All authors Alice Cartoceti, Paolo D'Agosta, Francesco Tumino, Valeria Russo, Carlo S. Casari, Andrea Li Bassi

Disordered Systems and Neural Networks · Cross-listed from physics.optics

Towards stealthy hyperuniform networks with optimal isotropic complete photonic band gaps using a novel inverse design procedure

Joel Steinegger, Paul J. Steinhardt, Christoph Räth et al. (+2 more)

We present a two-stage inverse design procedure for producing disordered stealthy hyperuniform trivalent photonic networks in two dimensions with isotropic complete photonic band gaps (PBGs) blocking light regardless of direction or polarization (TE or TM) over a wide frequency range. Most ordinary disordered systems fail to maintain complete PBGs as system size increases. The only known exceptions that remain open in the largest simulations have been generated by mapping stealthy hyperuniform point patterns into trivalent networks. However, the resulting networks are not truly stealthy hyperuniform two-phase media. Although their PBGs remain open, they are relatively narrow due to limited overlap between the TE and TM band gaps and broad band tails caused by localized defect states. By contrast, our two-stage inverse design aims to make the final network itself stealthy hyperuniform, achieving unprecedented near-optimal overlap between the TE and TM band gaps and a small defect state density at the band edges. We obtain not only single realizations with large PBGs, but a striking homogeneity across a large ensemble, effectively probing a network with 100,000 vertices. This ensemble-based band gap is comparable in width to the complete PBG of an anisotropic honeycomb photonic crystal with the same network parameters and nearly an order of magnitude wider than the previously widest known isotropic complete PBGs. Our designs can be fabricated using additive manufacturing, offering new pathways to manipulate electromagnetic waves for photonic technologies.
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All authors Joel Steinegger, Paul J. Steinhardt, Christoph Räth, Salvatore Torquato, Michael A. Klatt

Superconductivity

Zero-energy bound state trapped in line-shaped vortex in topological superconductor

P. Schlottmann

Fermion bound states in the core of a line-shaped vortex of a two-dimensional topological superconductor are investigated. The superconducting pairing potential, described in terms of elliptical coordinates, vanishes along a line defect with the two foci at the endpoints. The superconductivity is induced into a topological insulator via proximity effect with a type II s-wave superconductor. The spin and the momentum are perpendicularly locked by the strong spin-orbit coupling via Rashba interaction. A zero-energy Majorana state arises from the Berry phase together with a sequence of equally spaced fermion exitations. By solving the Bogoliubov-de Gennes equations using the method employed by Caroli, de Gennes and Matricon we calculate the energies, the wave-functions and spin-polarization of the bound states. An analytic expression for the local density of states within the vortex is obtained.
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Materials Science

Synthesis of the Elusive Bulk Iodide Double-Perovskite Semiconductor, Cs2AgBiI6: Microcrystals and Photoconductive Films

Faris Horani, Nicolas Nguyen, Carmelita Ro-Mendez et al. (+2 more)

Three-dimensional (3D) iodide double-perovskite (elpasolite) semiconductors have attracted interest as potential lead-free metal-halide absorber layers for solar applications. Although studied extensively by computational methods, they have remained largely inaccessible synthetically, consistent with their predicted thermodynamic instability. Here, we report the first synthesis of bulk Cs2AgBiI6, demonstrating both microcrystalline and thin-film forms. Microcrystalline powders of Cs2AgBiI6 were prepared via anion exchange from phase-pure Cs2AgBiBr6 microcrystals. The resulting iodide elpasolite shows broad absorption throughout the visible with a 1.70 +/- 0.05 eV optical bandgap and near-infrared photoluminescence centered at 1.03 eV. We identify the elimination of trace moisture in bulk Cs2AgBiBr6 as the critical factor enabling complete halide exchange and isolation of bulk Cs2AgBiI6 with phase purity. In inert atmosphere, microcrystalline Cs2AgBiI6 shows no decomposition when stored for months at room temperature or heated to ~70 {\deg}C, and it appears equally stable in dry air. Building upon these insights, we then demonstrate the preparation of phase-pure Cs2AgBiI6 films by flash thermal evaporation of Cs2AgBiBr6 followed by anion exchange. Photoconductivity measurements on such Cs2AgBiI6 films demonstrate photocarrier generation and transport, marking the first optoelectronic measurement on this elusive 3D iodide double perovskite.
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All authors Faris Horani, Nicolas Nguyen, Carmelita Ro-Mendez, Nicholas J. Adams, Daniel R. Gamelin

Soft Condensed Matter

Emergent Yielding from Structural Load Transfer in Disordered Soft Solids

Lalit Kumar

Yielding in disordered soft solids originates from the progressive redistribution of load-bearing capacity from recoverable elastic networks to frictional interactions through deformation-induced structural evolution. We present a unified, non-singular constitutive framework demonstrating that this mechanism naturally generates a finite yield stress and a smooth solid-to-fluid transition without prescribed yield criteria, constitutive switching, or divergent viscosities. The framework captures diverse transient and steady rheological phenomena, including Herschel-Bulkley behavior, stress overshoots, hysteresis, viscosity bifurcation, plug-flow formation, and thixotropic steady-state shear banding.
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Statistical Mechanics · Cross-listed from quant-ph

Emulating XX catalysts for quantum annealing via self-consistent transverse fields

Mohammadhossein Dadgar and Christopher L. Baldwin

Fully-connected transverse interactions have been considered as catalysts for quantum annealing that could mitigate exponentially small gaps and circumvent first-order phase transitions, but their experimental implementation remains challenging. In this work, we introduce a procedure for emulating their effects via a self-consistent transverse field. All that is required beyond conventional transverse-field annealing is the ability to make measurements in the transverse ($\hat{\sigma}^x$) basis. We show that this protocol yields identical dynamics in the large-system limit, and study the approach to that limit in numerical simulations of the (uniform) $p$-spin model. However, realizing the protocol in practice requires us to consider a series of approximate variants, each of whose errors we quantify and demonstrate can be made sufficiently small. Lastly, we show how to map the protocol onto annealing platforms that vary only a single control parameter. Even after the multiple stages of approximation, our procedure can generate dynamics that agree well with the original transverse-interaction catalyst, establishing self-consistent transverse fields as a viable alternative on near-term quantum annealers.
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Statistical Mechanics

Half dualization and non-invertible particle-vortex duality defect on lattice

Zhi-Qiang Gao

We introduce half dualization as a general principle to construct non-invertible duality defects. The construction performs a duality transformation only in a subregion of spacetime, leaving an interface between the original theory and its dual. A non-invertible duality defect can be hosted on this interface. Half dualization is applicable whenever a local duality transformation is available, and does not depend on the spacetime dimension. We demonstrate the construction procedure in the (2+1)-dimensional Villainized charge-$n$ XY model on a cubic lattice. Half dualization yields a non-invertible particle-vortex duality defect whose fusion with its orientation reverse produces a (1+1)-dimensional $\mathbb{Z}_n$ gauge theory on the fusion surface. We then apply half dualization to the $\mathbb{Z}_n$-gauged XY model relevant to the 3D XY$^\ast$ transition. In the gauged model, the half dualization interface hosts a gauge covariant duality wall, rather than a genuine gauge invariant duality defect. It flows to an invertible duality defect in infrared when the $\mathbb{Z}_n$ gauge theory is confined or Higgsed.
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Other Condensed Matter · Cross-listed from math.NA

Tensor-Network Finite Elements for Analytic Operator Equations

Abhijatmedhi Chotrattanapituk, Michael J. Landry, Chu-Liang Fu et al. (+1 more)

Operator equations (OEs) underpin quantitative modeling across science and engineering. Finite-element (FE) methods discretize continuous OEs into finite-dimensional algebraic systems, whereas tensor networks (TNs) provide flexible variational representations of correlated discrete systems. Here, we develop a framework that connects FE with TN for analytic OEs. The power of this method comes from its ability to convert highly non-linear partial differential equations into linear matrix equations. In particular, we show that FE discretization induces a hierarchy of multilinear interaction tensors, through which differential, integral, nonlinear, memory, and delay equations can be expressed within a common algebraic structure. The resulting systems are reformulated as weighted-residual optimization problems over TN degrees of freedom. Matrix-product-state calculations for one-dimensional linear and nonlinear diffusion reproduce conventional solutions with controlled error while preserving continuity and Neumann boundary conditions. The framework provides a common variational language for analytic OEs and establishes a direct connection between FE numerical formalism and TN variational algorithms, offering a general foundation for TN-based and quantum-inspired approaches to solving OEs.
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All authors Abhijatmedhi Chotrattanapituk, Michael J. Landry, Chu-Liang Fu, Mingda Li

Strongly Correlated Electrons

Three-Dimensional Non-Foliated Fractional Quantum Hall Phases with Irrational Anyons in Twisted van der Waals Multilayers

Seyoung Jin, Hyeonseo Lim, Youngwook Kim et al. (+1 more)

Three-dimensional fractional quantum Hall phases offer a route to intrinsically higher-dimensional topological order beyond simple stacks of two-dimensional quantum Hall liquids. Such phases can exhibit non-foliated, intrinsically three-dimensional entanglement structures, exponentially large topological degeneracies and quasiparticles with irrational braiding statistics. Their microscopic realization has remained elusive because Landau quantization in three dimensions generally leaves dispersive one-dimensional bands, favoring metallic and density-wave states over incompressible fractional liquids. Here we show that large-angle twisted van der Waals multilayers provide a practical route around this obstruction. Large twist angles suppress coherent interlayer tunneling through momentum mismatch, while the atomic-scale layer separation preserves strong interlayer Coulomb interactions. Using Monte Carlo calculations to compare the energies of an extensive set of 862 competing trial wavefunctions, we find that generalized Halperin states with quantum coherence extending across multiple consecutive layers are stabilized. In experimentally accessible magnetic-field regimes, these states replace the metallic spontaneous-interlayer-coherent phases that dominate conventional untwisted graphite-like multilayers. The resulting liquids realize non-foliated fractional quantum Hall order closely related to fractonic topological order, hosting quasiparticles with rational electric charges but irrational braiding statistics. Their large topological degeneracy and non-rational statistical phases may offer unconventional resources for quantum information storage and processing. Our results establish twisted van der Waals multilayers as a realistic materials platform for three-dimensional fractional Hall matter beyond conventional two-dimensional quantum Hall systems.
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All authors Seyoung Jin, Hyeonseo Lim, Youngwook Kim, Gil Young Cho

Mesoscale and Nanoscale Physics

SiMOS quantum-dot spin qubits enabled by extreme-ultraviolet lithography

Thomas Van Caekenberghe, Paul Steinacker, Bart Raes et al. (+31 more)

The realization of large-scale silicon quantum processors requires spin qubits compatible with advanced semiconductor manufacturing technologies, demanding lithographic processes that combine nanometer-scale precision with exceptional uniformity. Although the highest-performing silicon spin qubits demonstrated to date have relied on electron-beam (e-beam) lithography, its serial exposure process limits reproducibility studies and wafer-scale fabrication. Here, we demonstrate high-performance silicon metal-oxide-semiconductor (SiMOS) spin qubits fabricated using extreme-ultraviolet (EUV) lithography in a 300 mm semiconductor pilot line. We report wafer-scale quantum-dot uniformity metrics, including 100 % room-temperature gate-to-gate leakage yield and sub-nanometer control of critical gate dimensions. We characterize four double-dot systems realized in two triple-quantum-dot devices. Gate set tomography (GST) reveals consistently high fidelities across all four systems, with values up to 99.8 % for SPAM, 99.9 % for single-qubit gates, and 99.1 % for two-qubit gates. The devices exhibit highly reproducible exchange turn-on characteristics of 10-13 dec/V, indicating high fabrication uniformity enabled by EUV patterning. These results establish EUV lithography as a viable manufacturing technology for quantum processors based on high-fidelity SiMOS spin qubits.
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All authors Thomas Van Caekenberghe, Paul Steinacker, Bart Raes, Sofie Beyne, Clement Godfrin, Jacques Van Damme, Sylvain Baudot, Arne Loenders, Gulzat Jaliel, Stefan Kubicek, Johan De Backer, Yannick Hermans, Sugandha Sharma, Shuchi Kaushik, Yuchao Jiang, Yosuke Shimura, Roger Loo, Vukan Levajac, Kristof Moors, George Simion, Florian K. Unseld, Ensar Vahapoglu, Ajit Dash, Tuomo Tanttu, Chris C. Escott, Chih Hwan Yang, Andre Saraiva, Arne Laucht, Wee Han Lim, Nard Dumoulin Stuyck, Massimo Mongillo, Danny Wan, Andrew S. Dzurak, Kristiaan De Greve

Materials Science

DeepCormack: Fermi surface tomography using model-based data-driven algorithms

Georg F. B. Lovric, Bryn Drury, Carola-Bibiane Schönlieb et al. (+2 more)

The experimental reconstruction of the 3D two-photon momentum density (TPMD) via angular correlation of electron-positron annihilation radiation (ACAR) is a particularly useful method for studying material Fermi surfaces. It does not rely on low temperatures, UHV conditions, or strong magnetic fields, and enables the study of the spin-resolved electronic structure of materials. Yet, it remains a challenging inverse problem. Typically, 10^8 positron annihilation events are measured for 3–6 projections of the TPMD at different angles. The standard reconstruction approach is an ACAR adaptation of Cormack's method (the MCM) that leverages the inherent symmetry in the crystal's structure. However, the poor signal-to-noise ratio means collecting data of sufficient quality for Fermi surface studies can take months per sample. We present DeepCormack, a family of data-driven model-based reconstruction algorithms that augments the MCM by integrating supervised deep-learning models (CNN, MLP, and UNet) at various stages. To overcome the lack of large experimental training sets, we propose a method which leverages singular value decomposition with dynamic mode decomposition to generate realistic synthetic TPMD volumes, requiring only a single reference momentum density computed via density functional theory. On test data, DeepCormack improves reconstruction quality over MCM by about 8.5 dB PSNR at 200M counts and remains stable at reduced counts, enabling significantly faster acquisition times. Generalisation to experimental data depends strongly on how well the training distribution from the reference momentum density matches the sample. We therefore recommend pairing DeepCormack with a DFT calculation of the target material to create sample-specific training data. Our proposed method offers either much higher quality reconstructions, or enables significantly faster ones, on the order of weeks.
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All authors Georg F. B. Lovric, Bryn Drury, Carola-Bibiane Schönlieb, Stephen B. Dugdale, Ander Biguri

Mesoscale and Nanoscale Physics

Topological characterization of multifold band degeneracies in Altland-Zirnbauer symmetry classes

Askar Iliasov, Zoltán Guba, Tsuneya Yoshida et al. (+2 more)

Topological degeneracies of energy bands in crystalline matter are conventionally characterized by invariants computed on an enclosing sphere over which the spectrum remains gapped, a program completed for minimal degeneracies in all ten Altland-Zirnbauer (AZ) symmetry classes. Higher-order degeneracies have instead been studied almost exclusively under crystalline-symmetry protection. Here, we characterize generic $n$-fold degeneracies stabilized solely by AZ symmetries acting locally in momentum space. Their codimension grows quadratically with $n$, placing multifold nodes in parameter spaces combining momenta with tuning parameters or synthetic dimensions. Crucially, the enclosing-sphere paradigm faces a fundamental obstruction: two $(n\,{-}\,1)$-fold degeneracy loci emanating from the $n$-fold node necessarily pierce every choice of enclosing sphere, leaving no uniform spectral gap and thus no standard homotopy classification. We elevate this obstruction into the diagnostic itself. Namely, on the two nodal manifolds where the loci cross the sphere, complementary spectral gaps are restored, admitting conventional band invariants (Chern numbers, Stiefel-Whitney classes, and winding numbers). This observation establishes a general two-way correspondence: (1) the multifold node is topologically protected whenever the associated nodal manifolds are robustly linked, and (2) invariants on cycles of one manifold encode their linking numbers with cycles of the other. Carrying out this program for minimal models of all ten AZ classes, we recast multifold band topology as the topology of linked nodal manifolds and lay the foundation for characterizing multifold nodes in models with arbitrarily many bands.
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All authors Askar Iliasov, Zoltán Guba, Tsuneya Yoshida, Apoorv Tiwari, Tomáš Bzdušek

Quantum Gases · Cross-listed from physics.atom-ph

High-fidelity entanglement of polar molecules by dynamic geometric control

Scarlett S. Yu, Avikar Periwal, Jiaqi You et al. (+6 more)

In quantum information systems made of optical tweezer arrays of ultracold molecules, thermal motion of molecules degrades the coherence of their interactions, which limits entanglement fidelity and the concomitant scientific applicability of these systems. We show that by controlling the geometry of the dipolar interaction, even when a molecule occupies many motional states in the tweezer, coherence can be preserved. We characterize several geometries that suppress sensitivity to thermal fluctuations. We further use programmable, coherence-preserving motion of the molecules during entanglement to refocus dephasing from relative positional jitter of the tweezers, which is relevant even on the 10 nm scale. These methods yield substantially improved dipolar coherence and enable generation of two-molecule entanglement with a Bell state fidelity of $\mathcal{F}= 0.976^{+0.008}_{-0.011}$ in directly laser-cooled molecules.
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All authors Scarlett S. Yu, Avikar Periwal, Jiaqi You, Zirui Liu, Qinshu Lyu, Youngju Cho, Loïc Anderegg, Eunmi Chae, John M. Doyle

Strongly Correlated Electrons · Cross-listed from hep-th

The Infraparticle Edge

Soo-Jong Rey

I derive the charged-particle spectral edge from the quantum instrument of soft QED. I use two projections of that instrument. Tracing over unresolved photons gives the reduced hard-sector channel. Pushing the outcomes to total energy gives the inclusive energy distribution. Its Laplace exponent is fixed by the diagonal soft intensity. For ${\rm d} N_h(\omega)=\eta_h{\rm d}\omega/\omega+{\rm d} N_{h,\mathrm{reg}}(\omega)$, I obtain $\rho_{\mathrm{inc}}(s)\sim C\theta(s-m^2)(s-m^2)^{-1+\eta_h}$. I retain the coherence kernel and derive hard-sector dephasing and the spectral edge from two contractions of one soft environment. The diagonal coefficient $\kappa_{aa}$ fixes the endpoint exponent, while $\frac12(\kappa_{aa}+\kappa_{bb}-2\operatorname{Re}\kappa_{ba})$ fixes the dephasing exponent between hard alternatives. I then classify infrared energy marginals, derive the finite-resolution residue $Z(\mu)=(\mu/\Lambda)^{\eta_h}$, prove stability under infrared-integrable perturbations, and separate the bath exponent from a hard threshold exponent. For the one-electron spectral measure, the hard threshold factor is regular. The resulting edge has the local power law of a gapped unparticle spectrum, while its exponent remains a response coefficient of the unresolved photon sector.
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Materials Science

Surface Phase-Field-Crystal-Helfrich model for out-of-plane deformations in thin crystalline sheets with lattice mismatch

Emma Radice, Ingo Nitschke, Marco Salvalaglio et al. (+1 more)

Thin, flexible crystalline sheets exhibit unique elastic properties due to their ability to undergo out-of-plane deformations. Understanding this behavior requires a description that couples in-plane elasticity, out-of-plane deformation, and their coupling, taking the crystalline structure and its defects into account. We develop a multiscale description for these systems by extending the surface Phase-Field-Crystal-Helfrich model. The extension permits a spatially varying equilibrium lattice spacing, enabling the representation of localized lattice eigenstrain to mimic lattice mismatch in heterostructures. We validate the extended model against analytical predictions from classical Föppl-von Kármán equations for uniaxial compression and from Eshelby's inclusion problem. Using this validated framework, we then show how locally induced compressive stresses drive out-of-plane deformation in the sheets.
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All authors Emma Radice, Ingo Nitschke, Marco Salvalaglio, Axel Voigt

Quantum Gases · Cross-listed from physics.atom-ph

A cryogenic neutral-atom platform with full optical access and 2-hour trap lifetime

Akhil Kumar, Lorenzo Festa, Avishay Grinberg et al. (+10 more)

Neutral-atom quantum processors are rapidly scaling toward system sizes of more than ten thousand qubits, allowing for the realization of a new class of quantum computing algorithms and quantum simulation experiments. However, current neutral-atom platforms generally have to find a compromise between the optical accessibility and the storage time of atoms in optical potentials, limiting the available qubit numbers. Here we report on the operation of a novel, cryogenically enhanced, neutral-atom apparatus that overcomes these apparently conflicting requirements. We demonstrate vacuum-limited trapping lifetimes of up to two hours of single $^{88}\mathrm{Sr}$ atoms in an optical tweezer array while preserving full optical access and without the need for complex cryogenic enclosures. Our measurements show that exceptionally long single-atom lifetimes can be achieved with a relatively simple cryostat design. Our architecture can be straightforwardly ported to other atomic species and shows a viable path for scaling up to sorted arrays of tens of thousands of atoms.
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All authors Akhil Kumar, Lorenzo Festa, Avishay Grinberg, Eran Reches, Dimitrios Tsevas, Kevin P. Mours, Zhao Zhang, Robin Eberhard, Sebastian Blatt, Andrea Alberti, Johannes Zeiher, Immanuel Bloch, Max Melchner

Soft Condensed Matter

Active Quantum Nematics: The First Quantization

Ghansham Chandel and Siddhartha Das

Nematic symmetry entails conserved quantized quantities such as number of topological defects and vorticity cells. Correspondingly, countless quantum analogies have been found in Active Nematics. We formalize Active Nematics and Liquid Crystal theory into the framework of Quantum Mechanics by introducing a complex valued Nematic Wavefunction to the Beris Edward equations, thus splitting spatiotemporally varying nematic systems into quantized states. We obtain the Planck's energy-frequency relationship for active micro-swimmers such as peristaltic worms and bacterium as a consequence of local complex phase-symmetry of the governing equations, similar to the gauge formulation of Electromagnetism. For organisms operating on diffusive chemotaxis, we obtain predator-prey dynamics that evolve to maximize/minimize pheromones field gradient overlap. Furthermore, when quantizing beating hearts, similar to the orbitals of hydrogen atoms, the state-function allows us to characterize hearts not only through the rhythm, but also the spaciotemporal distribution of contractile activity of various harmonics among healthy and unhealthy hearts.
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