Superconductivity
Supercurrents in Josephson junctions with chiral molecular potentials
Oleg Kuliashov, Alberto Cappellaro, Oded Millo et al. (+3 more)
The influence of
chiral molecular potentials on phase-coherent transport in superconducting Josephson junctions is investigated. Within a Bogoliubov–de Gennes tight-binding framework, a superconducting–normal–superconducting (SNS) junction functionalized by adsorbed
chiral molecules is modeled, where electrostatic gradients generated by the molecules induce
spin–orbit coupling in the normal region. The
equilibrium charge current–phase relation is found to remain largely insensitive to molecular chirality in symmetric, zero-field configurations. In contrast, the
spin-polarized
equilibrium current exhibits a pronounced chirality-dependent response, with opposite enantiomers producing distinct and anisotropic
spin-polarized Josephson currents. The resulting handedness contrast can be enhanced through control parameters such as molecular orientation and the strength of the induced
spin–orbit coupling. The temperature dependence of these currents further shows that the chirality-dependent signatures persist across a range of temperatures well below the superconducting critical temperature. These results identify Josephson interferometry as a phase-sensitive setting for probing chirality-dependent
spin structure and highlight
spin-polarized superconducting transport as a controlled route toward integrating
chiral molecular functionality into superconducting spintronic devices.
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All authors Oleg Kuliashov, Alberto Cappellaro, Oded Millo, Yossi Paltiel, Mikhail Lemeshko, Ragheed Alhyder
Mesoscale and Nanoscale Physics
Tuning correlated states of twisted mono-bilayer graphene with proximity-induced spin-orbit coupling
Jeyong Park, Mingdi Luo, Louk Rademaker et al. (+3 more)
We study the correlated ground states of twisted mono-
bilayer graphene with and without proximity-induced
spin-orbit coupling (SOC) from a transition-metal dichalcogenide layer placed on top. We perform self-consistent Hartree-Fock calculations that allow the variational space to include multi-$Q$ translational
symmetry broken states for all integer and half-integer fillings of the conduction bands, where signatures of correlated, topological states have been reported experimentally. We find interaction-induced
insulators that retain moiré translational
symmetry at integer fillings, but that break this
symmetry at half-integer fillings. We argue that translational
symmetry breaking arises from half-filled polarized bands, even when SOC is present. Yet, we find that small SOC can already crucially affect the
spin nature of correlated states. Generally, Ising SOC favors out-of-plane
spin polarization and
spin-valley locking, while Rashba SOC favors in-plane
spin order. If only one of these two terms is present, we find that, depending on the type of SOC, it drives a transition from a tetrahedal antiferromagnet to either a coplanar, non-coplanar, or collinear
spin-density wave state for half-integer fillings. The frustration associated with the simultaneous presence of both types of SOC can induce
chiral, non-coplanar order in parameter ranges where the ground state in the absence of SOC is collinear.
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All authors Jeyong Park, Mingdi Luo, Louk Rademaker, Jurgen Smet, Mathias S. Scheurer, Laura Classen
Materials Science
Sliding Ferroelectricity Driven Spin-Layertronics in Altermagnetic Multilayers
Rui Peng, Guangxu Su, Yangyang Fan et al. (+3 more)
The synergy of ferroicity with altermagnetism offers a novel platform for designing multifunctional altermagnetic-spintronic device technology. In this work, we propose a mechanism to achieve nonvolatile electrical manipulation of
spin and layer degrees of freedom in an altermagnetic
bilayer via sliding ferroelectricity. Using first-principles calculations, we show that an interlayer translation can induce a switchable out-of-plane ferroelectric polarization in
bilayer CuF2, which directly couples to and reverses the d-wave altermagnetic
spin splitting. Notably, the altermangetic
spin splitting is layer-locked, the sliding ferroelectricity-driven switching thus embodying a nonvolatile
spin-layertronics functionality that couples
spin-polarized transport and layer degree of freedom in a single platform. We show that in quadrilayer CuF2, four polarization states are identified which may offer multi-state logic device applications. These findings establish sliding ferroelectricity as a versatile tool for designing voltage-controlled, high-speed and energy-efficient
spin-layertronic devices based on altermagnets.
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All authors Rui Peng, Guangxu Su, Yangyang Fan, Jiaan Li, Fanxin Liu, Yee Sin Ang
Materials Science · Cross-listed from physics.optics
Fast Programming of In-Plane Hyperbolic Phonon Polariton Optics Through van der Waals Crystals using the Phase-Change Material In3SbTe2
Lina Jäckering, Umberto Saldarelli, Aaron Moos et al. (+8 more)
The high directionality of
hyperbolic phonon polaritons (HPhPs) has opened radically new ways to route and steer the flow of energy at the nanoscale. However, launching HPhPs requires fabricating efficient and precisely aligned polariton launching structures, which remains time-consuming and expensive with conventional nanofabrication approaches. Recently, using optical
laser pulses, polariton launching structures have been programmed into the plasmonic phase-change material In3SbTe2. Here, we leverage this approach to reconfigure HPhPs by programming a variety of launching and confining nanostructures through {\alpha}-MoO3 flakes deposited onto In3SbTe2. Importantly, optical programming after flake deposition enables
alignment of launching stripes to the [001]-axis of the flake, essential to control the directional polariton propagation. We showcase these capabilities in a variety of structures: i) an optically programmed disk, showing similar tuning ranges and confinement as focusing by gold disks; and ii) a cavity for in-plane HPhPs created by reconfiguring the single disk to a double disk structure, tailoring the confinement by simply reprogramming the disk distance. Our fabrication scheme offers fast turn-around times, flexible
alignment and the opportunity to reconfigure the structures. Thus, it is a fast, efficient and versatile way to tailor propagation and confinement of highly directional polaritons on demand.
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All authors Lina Jäckering, Umberto Saldarelli, Aaron Moos, Lukas Conrads, Enrique Terán-García, Christian Lanza, Aitana Tarazaga Martín-Luengo, Gonzalo Álvarez-Pérez, Pablo Alonso-González, Matthias Wuttig, Thomas Taubner
Materials Science
Helium-Cooled Cryogenic STEM Imaging and Ptychography for Atomic-Scale Study of Low-Temperature Phases
Noah Schnitzer, Mariana Palos, Geri Topore et al. (+7 more)
Much of the exotic functionality of
prime interest in
quantum materials emerges from structural and electronic ground states that can only be accessed at cryogenic temperatures. Understanding device operation therefore requires structural characterization under the same low-temperature conditions at which these functional phases exist, as room-temperature measurements often probe a different structural state. Achieving atomic-resolution in scanning transmission electron microscopy imaging and particularly 4D-STEM electron ptychography at
liquid helium temperature has remained extremely challenging because even small amounts of drift, vibration, and thermal instability associated with the cryogen can disrupt the stringent stability requirements of atomic-resolution STEM. In this work we demonstrate atomic-resolution STEM and multislice electron ptychography at temperatures as low as 20 K using a commercial helium cooled holder. We find that rapid scans and a multi-stage registration workflow are critical to reducing artifacts associated with cryogenic instability for atomic-resolution imaging, while for ptychography scan position correction including compensation for coupling between probe aberrations and position refinement is necessary for successful reconstructions. Together these results establish a pathway for reliable atomic-resolution STEM and ptychography at low temperature, enabling direct visualization of structural ground states relevant to
quantum technology.
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All authors Noah Schnitzer, Mariana Palos, Geri Topore, Nishkarsh Agarwal, Maya Gates, Yaqi Li, Robert Hovden, Ismail El Baggari, Suk Hyun Sung, Michele Shelly Conroy
Superconductivity
Gap structure and phase diagram of twisted bilayer cuprates from a microscopic perspective
Siddhant Panda, Andreas Kreisel, Laura Fanfarillo et al. (+1 more)
Since the prediction of a time-reversal
symmetry breaking (TRSB) $d+id^\prime$ state in twisted
bilayer cuprate
superconductors by Can et al. (Nat.Phys. 17,519(2021)), several experiments have attempted to detect this state, yielding conflicting results. At present, it is not clear which differences in samples or experimental conditions might explain these discrepancies. In this work, we perform a tight-binding
lattice model calculation with phenomenological interlayer tunneling, examining the order parameter as a function of twist angle, interlayer tunneling, doping, and temperature. We observe the TRSB state to be correlated to the position of the Van Hove singularity in the normal state, which changes not only as a function of doping but also the tunneling strength. Two such phases are identified as nominally consistent with in-plane $d+id'$ and $d+is$ order, but with unexpected transformation properties under
bilayer symmetry operations. We calculate the Josephson critical current, in particular examining the angle dependence for various tunneling strengths. Finally, we discuss the existing experiments in the context of our results.
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All authors Siddhant Panda, Andreas Kreisel, Laura Fanfarillo, Peter Hirschfeld
Statistical Mechanics · Cross-listed from quant-ph
Star Topology Optimizes the Charging Power of Quantum Batteries
Matthieu Sarkis, Oskar A. Prośniak, Samuel Nigro et al. (+1 more)
Quantum batteries are
quantum systems that store energy and deliver it on demand, and their practical value hinges on how fast they can be charged. While collective charging protocols and global control are known to enhance charging power, it remains unclear how the battery's internal interaction architecture itself constrains performance. Here we study interacting fermionic batteries whose internal couplings are encoded by a graph adjacency
matrix, charged via a simple interaction with an external fermionic device. We prove that the
star topology maximises the early time charging power, which proxies the maximal average power - a widely used
quantum battery quality metric. We substantiate the result numerically by an exhaustive sweep over all graphs with $N\leq 7$ vertices and by
benchmarks against random graph ensembles at larger $N$. Our findings shed light on architecture as a controllable knob for fast charging and motivate hub-and-spoke designs in scalable
quantum-battery platforms.
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All authors Matthieu Sarkis, Oskar A. Prośniak, Samuel Nigro, Alexandre Tkatchenko
Statistical Mechanics · Cross-listed from quant-ph
Open quantum systems beyond equilibrium: Lindblad equation and path integral molecular dynamics
Benedikt M. Reible, Somayeh Ahmadkhani and Luigi Delle Site
The Lindblad equation determines the time
evolution of the density operator of open
quantum systems. While valid for any system size, its use is, in practice, restricted to prototype/surrogate models with the aim of tackling specific aspects of the overall
quantum complexity of a multi-atomic system. Path integral molecular dynamics (PIMD) instead provides static and dynamical
quantum statistical averages of physical observables for systems in
equilibrium composed of up to thousands of atoms over timescales up to nanoseconds, under the condition that short-time
quantum coherence is not relevant for the properties of interest. PIMD relies on the well-established technique of molecular dynamics (MD) with its associated classical trajectories. However, it cannot describe a direct time
evolution of a system and its convergence to a stationary state in situations out of
equilibrium. In this work, we analyze the link between the Lindblad equation and PIMD; specifically, we will discuss how PIMD can actually be used to calculate the time
evolution of ensemble-averaged physical observables and their convergence to a stationary state for situations out of
equilibrium, bypassing the need of explicitly solving the Lindblad equation. Yet, at the same time, the Lindblad equation and PIMD are linked to one another through a formal relation of equivalence, which provides an argument for the consistency of PIMD results, namely the positivity of the density operator at any time. A numerical study of a prototype system, which is of interest in chemical physics, will be used to showcase the method.
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Materials Science
Ab initio informed electronic stopping models for light ion propagation in metals
Evgeniia Ponomareva, Artur Tamm and Andrea E. Sand
Understanding ion-matter interactions at the atomistic level is key to advancing materials for the
semiconductor industry, space systems, and
nuclear fusion technologies. However, most atomistic frameworks still rely on simplified descriptions of how ions transfer energy to the electronic subsystem, overlooking the sensitivity of this process to the actual ion path. Existing electron-ion interaction models, such as the tensorial unified two-temperature model, were developed to study self-irradiation scenarios, but their suitability for light-ion irradiation remains unexplored. Here, we propose that for light projectiles, stepping back from the tensorial formulation toward a simpler, local model of electronic stopping provides a more efficient and physically transparent trajectory-dependent description. We parameterize and validate both models for hydrogen and helium in tungsten using ab initio electronic stopping data and large-scale ion range simulations, benchmarked against existing experimental data. This provides a consistent framework for including nonadiabatic electronic stopping in atomistic simulations of light-ion energy dissipation.
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Materials Science
Magnetic criticality and magnetocaloric response in MnBi$_2$Te$_4$ and MnBi$_4$Te$_7$
Nazma Firdosh, Shreyashi Sinha and Sujit Manna
MnBi$_2$Te$_4$ and MnBi$_4$Te$_7$ are
antiferromagnetic topological
insulators belonging to the MnBi$_{2n}$Te$_{3n+1}$ series, where structural layering provides a natural route to tune
magnetic interaction in van der Waals magnets. Despite extensive interest in their topological properties, how the insertion of Bi$_2$Te$_3$ quintuple layers modifies
magnetic critical fluctuations near the
antiferromagnetic transition remains unresolved. Here, we combine scanning tunneling microscopy (STM), critical scaling analysis, and magnetocaloric measurements to directly correlate real-space structures with
magnetic criticality. STM reveals atomically flat septuple-layer terraces in MnBi$_2$Te$_4$ whereas MnBi$_4$Te$_7$ displays coexisting septuple and quintuple layer terminations reflecting its alternating stacking sequence. MnBi$_2$Te$_4$ exhibits robust three-dimensional Ising-like critical behavior together with a distinct low-temperature first-order transition. In contrast, MnBi$_4$Te$_7$ displays crossover-dominated criticality arising from weakened interlayer exchange and competing
magnetic phases. Correspondingly, the magnetocaloric response differs significantly between the two compounds. MnBi$_2$Te$_4$ shows dual-type magnetocaloric behavior with a sharp field-induced sign reversal of the isothermal
magnetic entropy change ($-\Delta S_M$). It exhibits both inverse ($-\Delta S_M < 0$) and conventional ($-\Delta S_M > 0$) magnetocaloric effects. In contrast, MnBi$_4$Te$_7$ shows only conventional magnetocaloric response with a broad positive
entropy peak. These results establish structural layering as a key parameter governing
magnetic critical fluctuations and magnetocaloric behavior in MnBi$_{2n}$Te$_{3n+1}$ topological magnets.
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Statistical Mechanics
Dissipation- versus Chaos-Induced Relaxation in Non-Markovian Quantum Many-Body Systems
Gabriel Almeida, Pedro Ribeiro, Masudul Haque et al. (+1 more)
In interacting
quantum many-body systems, relaxation toward
equilibrium reflects a competition between internal chaotic dynamics and environmental dissipation. While conventional Markovian baths typically produce exponential decay, non-Markovian dissipation can give rise to more intricate behavior, including algebraic relaxation. We study an open Sachdev-Ye-Kitaev (SYK) model coupled to a pseudogapped fermionic bath, using the Keldysh formalism to compute steady-state correlations in the large-$N$ limit. Our results uncover a rich dynamical phase diagram, with regimes of bath-driven power-law relaxation, chaos-driven exponential decay, and an intermediate pre-relaxation phase where exponential decay crosses over to algebraic decay. These findings demonstrate that non-Markovian environments can qualitatively reshape relaxation mechanisms in strongly correlated
quantum many-body systems.
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All authors Gabriel Almeida, Pedro Ribeiro, Masudul Haque, Lucas Sá
Materials Science
Engineering Magnetic Anisotropy in Permalloy Films via Atomic Force Nanolithography
Abhishek Naik, Cyril Delforge, Nicolas Lejeune et al. (+5 more)
Atomic force nanolithography provides a precise method for sculpting
magnetic thin films, enabling controlled engineering of
magnetic anisotropy in soft ferromagnets at the microscale. We demonstrate that nanoscale groove arrays patterned into permalloy (Ni80Fe20) films induce a robust in-plane uniaxial anisotropy, with the easy axis aligned along the groove direction. The anisotropy field is shown to increase with decreasing groove period and increasing engraving depth, offering continuous tunability of
magnetic hardness within a single fabrication step. Artificially engraved microstructures further allow domain configurations and domain-wall trajectories to be directed along predefined pathways, exemplified by the creation of a chessboard-like
magnetic landscape. Owing to its adaptability to diverse
ferromagnetic materials and arbitrary corrugation geometries, this approach provides a versatile platform for tailoring in-plane
magnetic anisotropy. Concrete applications are demonstrated in the design of magnonic elements and anisotropic magnetoresistance sensors.
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All authors Abhishek Naik, Cyril Delforge, Nicolas Lejeune, Daniel Stoffels, Joris Van de Vondel, Kristiaan Temst, Alejandro V. Silhanek, Emile Fourneau
Strongly Correlated Electrons
Electronic Structure and Resonant Circular Dichroism of La$_{0.7}$Sr$_{0.3}$MnO$_3$ from Soft X-ray Angle-Resolved Photoemission
Øyvind Finnseth, Damian Brzozowski, Anders Christian Mathisen et al. (+12 more)
Coupling between
spin, orbital, charge, and
lattice degrees of freedom in transition-metal
oxides produces a variety of electronic and
magnetic phenomena of importance for future technologies. Here, we explore the electronic band structure of a (111)-oriented La0.7Sr0.3MnO3 thin film through soft X-ray angle-resolved photoemission spectroscopy (ARPES). The measurements agree with the electronic band structure calculated with density functional theory using Hubbard U correction. Furthermore, we probe the circular dichroism in ARPES, and observe a pronounced momentum- resolved
magnetic circular dichroism in resonant photoemission from the Mn L-edge. The approach combines the momentum- and
spin-selectivity of ARPES and X-ray
magnetic circular dichroism, respectively, which could provide a useful approach for the study of unconventional magnetism.
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All authors Øyvind Finnseth, Damian Brzozowski, Anders Christian Mathisen, Stefanie Suzanne Brinkman, Xin Liang Tan, Fabian Gohler, Benjamin A. D. Williamson, Kristoffer Eggestad, Meng-Jie Huang, Jens Buck, Moritz Hoesch, Kai Rossnagel, Sverre M. Selbach, Hendrik Bentmann, Ingrid Hallsteinsen
Strongly Correlated Electrons
Pairing and charge distribution in Emery ladders preserving the ratio of Cu to O atoms
Gökmen Polat and Eric Jeckelmann
We study the Emery model (three-band Hubbard model) for superconducting cuprates on three distinct ladder-like
lattices that are supercells of the CuO$_2$ plane and thus preserve the ratio of copper to oxygen atoms. Using the density-
matrix renormalization group method we confirm that these Emery ladders are charge-transfer
insulators for the hole concentration corresponding to undoped cuprates but become Luther-Emery
liquids with enhanced pairing correlations upon doping. The preservation of the Cu to O ratio allows us to study the distribution of charges between these atoms in the Luther-Emery phase. We show that these Emery ladders can describe the relations between charge distribution, pairing strength, and interactions that have been observed in the Emery model on two-dimensional clusters and in experiments.
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Statistical Mechanics · Cross-listed from quant-ph
Universal purification dynamics in real non-unitary quantum processes
Federico Gerbino, Donghoon Kim, Guido Giachetti et al. (+2 more)
We study purification dynamics in monitored
quantum processes governed by ensembles of
quantum circuits in different random-
matrix symmetry classes. We analyze the universal aspects that emerge away from the measurement induced phase transition and inside the volume/weak measurement phase and in the scaling limit of large time and
Hilbert space dimension. We present two toy models that reveal two complementary
visions and provide quantitative access to universal scaling: i) a discrete-time dynamic in which each time step corresponds to multiplication by a Gaussian random
matrix; ii) weak continuous-time monitoring that induces a Dyson brownian motion of the
eigenvalues of the density
matrix. The first approach provides an algebraic characterization based on rotational invariance emerging in Kraus's operator space, focusing in particular on the
unitary and orthogonal cases, respectively $\beta=2$ and $\beta=1$, with $\beta$ the Dyson random-
matrix index. The second approach, on the other hand, allows for a unified treatment for any $\beta$, thanks to the mapping of the Fokker-Planck
evolution of
eigenvalues onto the Calogero-Sutherland integrable
Hamiltonian diagonalized in terms of Jack
polynomials. We provide explicit expressions for the universal decrease of Rényi
entropies. We show that, approaching the universal scaling limit, numerical simulations of different models agree with each other and with our theoretical predictions. Our results clarify the existence of different classes of universality for the purification process in hybrid
quantum systems, accessible in random
circuit architectures and weak measurement protocols.
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All authors Federico Gerbino, Donghoon Kim, Guido Giachetti, Andrea De Luca, Xhek Turkeshi
Superconductivity
Pauli-limited upper critical field and anisotropic depairing effect of La2.82Sr0.18Ni2O7 superconducting thin film
Ke Wang, Maosen Wang, Wei Wei et al. (+10 more)
We investigate the upper critical field and superconducting anisotropy of epitaxial La2.82Sr0.18Ni2O7 thin films, which show a sharp superconducting transition at Tc=31.6 K. Near Tc, superconductivity exhibits thickness-limited two-dimensional characteristics. Upon cooling, the out-of-plane coherence length decreases below the sample thickness of 6 nm, corresponding to a 3-unit-
cell film, indicating a crossover to intrinsic three-dimensional bulk superconductivity. High-field transport measurements reveal large upper critical fields with a small anisotropy ratio gama~1.34, comparable to bulk Ruddlesden-Popper nickelates. At low temperatures, the in-plane (ab) upper critical field Hc2(ab) is strongly suppressed by
spin-paramagnetic pair breaking and approaches the Pauli limit (Hc2(Pauli)=58 T), while Hc2(c) remains largely unaffected. This anisotropic Pauli limitation accounts for the reduced upper critical field anisotropy and supports the conclusion that superconductivity in these films is fundamentally three-dimensional bulk like. Our results highlight the essential role of
spin-paramagnetic effects in shaping the high-field superconducting phase diagram of Ruddlesden-Popper nickelates.
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All authors Ke Wang, Maosen Wang, Wei Wei, Bo Hao, Mengqin Liu, Qiaochao Xiang, Xin Zhou, Qiang Hou, Yue Sun, Zengwei Zhu, Sheng Li, Yuefeng Nie, Zhixiang Shi
Strongly Correlated Electrons
Non-Collinear and Non-Coplanar Magnetic Orders in 1/1 Periodic Approximant to the Icosahedral Quasicrystal
Shinji Watanabe and Tatsuya Iwasaki
Ground-state properties of rare-earth based 1/1 periodic approximants of icosahedral quasicrystal are clarified theoretically on the basis of an effective model for magnetism taking into account uniaxial anisotropy arising from crystalline electric field. By performing numerically-exact calculation on the 1/1 approximant
crystal with a
lattice constant $a$=14.725 Å, we have determined the ground-state phase diagram for
ferromagnetic interactions. The result shows that eight kinds of noncollinear and noncoplanar
magnetic structures are stabilized, whose
magnetic space groups are identified as $I_{\rm P}m'\bar{3}'$, $C2'/m'$ and $R\bar{3}$. We have clarified the degeneracy of each ground state, which is expected to be reflected in the numbers of the domains. By analyzing each state, the
magnetic as well as topological properties are revealed. Our results are shown to explain the measured
magnetic structures in the 1/1 approximants and the effective model is discussed to be useful for understanding the
magnetic structures and their topological properties in broad range of rare-earth based 1/1 approximants.
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Materials Science
Dielectric Tensor of CrSBr from Spectroscopic Imaging Ellipsometry
Pierre-Maurice Piel, Sebastian Schaper, Aleksandra Łopion et al. (+4 more)
Chromium sulfur bromide (CrSBr) is a
magnetic van der Waals
semiconductor with a direct bandgap and pronounced anisotropy in its electronic, optical,
spin and
lattice degrees of freedom. Here, we employ spectroscopic imaging ellipsometry (SIE) and Mueller-
matrix analysis to determine the full dielectric tensor of paramagnetic CrSBr thin films. Our measurements reveal optical anisotropy, characterized by three distinct diagonal components of the dielectric tensor. The in-plane elements are dominated by prominent excitonic resonances polarized along the two main crystallographic axes. Two main excitonic bands (A and B
excitons) centered around 1.3eV and 1.7eV, respectively, are identified; the A-
exciton polarized along the b-crystallographic direction, whereas the B-
exciton appears to consist of two nearly degenerate contributions polarized along two orthogonal in-plane
crystal axes. These results provide fundamental insight into anisotropic light-matter interactions in CrSBr, relevant for future
spin-optoelectronic and photonic applications.
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All authors Pierre-Maurice Piel, Sebastian Schaper, Aleksandra Łopion, Jakob Henz, Aljoscha Soll, Zdenek Sofer, Ursula Wurstbauer
Mesoscale and Nanoscale Physics
Fast readout for large scale spin-based qubits
X. Luo, B. Bertrand, H. Niebojewski et al. (+3 more)
In this letter, we present fast readout of Pauli
spin blockade phenomena and interdot coupling tunability in a silicon double
quantum dot (DQD) fabricated using industry-compatible processes. The interdot couplings are tuned with a second self-aligned gate layer. The charge sensing and
spin readout are performed by using gate-based reflectometry techniques. The results pave the way for scalable fast readout of large-scale industry-standard manufactured Si
spin qubit arrays.
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All authors X. Luo, B. Bertrand, H. Niebojewski, F. Martins, C. Smith, T.-Y. Yang
Disordered Systems and Neural Networks · Cross-listed from quant-ph
Probing the ergodicity breaking transition via violations of random matrix theoretic predictions for local observables
Venelin P. Pavlov, Peter A. Ivanov, Diego Porras et al. (+1 more)
Quantum many-body systems can exhibit distinct regimes where dynamics is either ergodic, dynamically exploring an extensive region of available state-space, or non-ergodic, where the dynamics may be restricted. An example is the many-body localization (MBL) transition, where disorder induces non-ergodic behaviour. Most measures of ergodicity notably rely on global quantities, such as level spacing statistics. We explore the ability for a subsystem to probe the ergodicity of dynamics via measurement of local observables, and use expected results from random
matrix theory (RMT) as a
benchmark for the ergodic regime. We exploit two predictions from RMT as ergodicity is broken: the time
evolution of the
quantum Fisher information, and a fluctuation-dissipation relation. These are investigated in three different ergodicity breaking mechanisms, namely, as a consequence of transition to integrability, MBL, and
Quantum Many-Body Scars (QMBS). We show that the predicted behaviour from RMT can be used as a potential witness for transition to non-ergodic behaviour from the measurement of local observables alone.
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All authors Venelin P. Pavlov, Peter A. Ivanov, Diego Porras, Charlie Nation
Statistical Mechanics · Cross-listed from physics.plasm-ph
Magnetohydrodynamics in turbulent dynamo regime: the stability problem
Michal Hnatič, Tomáš Lučivjanský, Lukáš Mižišin et al. (+2 more)
This paper investigates
stochastic solenoidal magnetohydrodynamics within the field-theoretic Martin-Siggia-Rose-De Dominicis-Janssen formalism, with a specific focus on the stability of the system when spatial mirror (parity)
symmetry is explicitly broken. Under helical forcing, the one-particle-irreducible
magnetic response function already at one loop contains a curl-type contribution that dominates the bare resistive term in the infrared limit, leading to exponential instability of the trivial state $\langle \mathbf{b} \rangle = \mathbf{0}$. We re-examine a stabilization mechanism proposed in [L. T. Adzhemyan, et al., Theor. Math. Phys. 72, 940-950 (1987)], in which the system evolves into a phase with a dynamically spontaneously broken rotational
symmetry and a generated mean
magnetic field $\langle \mathbf{b} \rangle = \mathbf{B}_0$. By deriving a self-consistency condition for $ \mathbf{B}_0$, we show that for any physically admissible (infrared) form of the pumping function, the model admits only a singular solution. We illustrate this with the standard power-law and "massive" pumping functions. We further show that previous claims of a finite $ \mathbf{B}_0$ arose from an inconsistent truncation of asymptotic expansions. We argue that a consistent physical resolution requires including a bare curl term in the
stochastic induction equation, which naturally arises from a parity-violating modification of Ohm's law. With this modification, stabilization of the system by spontaneous
symmetry breaking becomes a viable field-theoretic description of large-scale mean-field generation (turbulent dynamo) in helical turbulent magnetohydrodynamics.
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All authors Michal Hnatič, Tomáš Lučivjanský, Lukáš Mižišin, Yurii Molotkov, Andrei Ovsiannikov
Materials Science
Low-loss phase-change material based programmable mode converter for photonic computing
Xueyang Shen, Ruixuan Chu, Ding Xu et al. (+3 more)
Phase-change materials (PCMs)-based integrated photonic
memory offers a viable pathway for the development of neuromorphic computing chip. The sizable optical contrast in the telecom band between amorphous and crystalline phases of PCM, in particular, Ge2Sb2Te5 (GST), is used for multilevel programming. However, the high extinction coefficient k of crystalline GST leads to high optical loss, posing a serious challenge for scaling up the device array for practical use. In this work, we focus on the atomic understanding and application of the so-called low-loss PCM, Sb2Se3, through multiscale simulations. First, we elucidate the bonding origin of the wavelength dependent optical properties of amorphous and crystalline Sb2Se3 via ab initio calculations. Given the suppressed k in the telecom band, we design a programable mode converter (PMC) waveguide device that utilizes only the contrast in refractive index n between amorphous and crystalline Sb2Se3 to encode multiple optical levels per waveguide device. The finite-difference time-domain simulations show that a single PMC device can achieve 5-bit programming precision (32 levels) via direct
laser writing, and the photonic tensor core formed by the PMC array could possibly be scaled to 128*128. Finally, a thorough comparison between low-loss PCM and conventional PCM is provided.
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All authors Xueyang Shen, Ruixuan Chu, Ding Xu, Yuan Gao, Wen Zhou, Wei Zhang
Mesoscale and Nanoscale Physics
Gauge transformation for pulse propagation and time ordered integrals
Adel Abbout
We investigate a gauge transformation based on the successive elimination of time-dependent onsite potentials at individual sites in finite or infinite systems. Our analysis shows that this transformation renormalizes the inward hoppings by a phase factor $e^{i \phi(t)}$ and the outward hoppings by $e^{-i \phi(t)}$. We further demonstrate how this procedure facilitates the reduction and simulation of pulse propagation in scattering systems, while significantly simplifying the time-ordered integrals involved in the time
evolution operator for time-dependent Schrodinger equation.
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Statistical Mechanics · Cross-listed from quant-ph
Experimental simulation of non-equilibrium quantum piston on a programmable photonic quantum computer
Govind Krishna, Rohan Yadgirkar, Balakrishnan Krishnakumar et al. (+6 more)
Quantum fluctuation relations provide a microscopic formulation of thermodynamics beyond
equilibrium, but experimentally accessing many-body
quantum work statistics remains an outstanding challenge. The
quantum piston constitutes a canonical model of boundary-driven nonequilibrium dynamics, where finite-time deformation of a confining potential generates non-adiabatic transitions, dissipation and irreversibility. Here we experimentally simulate the nonequilibrium dynamics of a two-
boson quantum piston on a programmable photonic
quantum computer. Using two indistinguishable
photons, we encode a truncated piston propagator through a quasi-
unitary embedding, with an ancilla mode representing leakage into higher-energy states outside the resolved
manifold. This architecture enables direct reconstruction of thermodynamic transition statistics for both expansion and compression protocols as functions of driving speed and final trap length. We observe the crossover from quasi-adiabatic to strongly non-adiabatic
evolution and show that bosonic interference restructures the resulting two-particle Fock-state populations and work distributions. The measured statistics are in close agreement with theoretical predictions and satisfy the Jarzynski equality across expansion and compression protocols for cyclic driving we further quantify irreversibility through dissipated work and state overlap. Our work identifies programmable photonic
quantum hardware as a powerful platform for simulating nonequilibrium
quantum thermodynamics and for experimentally resolving how indistinguishability and many-body interference shape
quantum work, dissipation and
entropy production.
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All authors Govind Krishna, Rohan Yadgirkar, Balakrishnan Krishnakumar, Andrea Cataldo, Ze-Sheng Xu, Johannes W. N. Los, Val Zwiller, Jun Gao, Ali W. Elshaari
Materials Science
High-Throughput-Screening Workflow for Predicting Volume Changes by Ion Intercalation in Battery Materials
Aljoscha Felix Baumann, Daniel Mutter, Daniel F. Urban et al. (+1 more)
Mechanical stresses and strains developing locally within the microstructure of active ion-battery-electrode materials during charge-discharge cycles can compromise their long-term stability. In this context, crystalline compounds exhibiting low volume changes are of particular interest. Atomistic simulations can be employed to quantify the volume change of the
crystal structure upon intercalation and deintercalation of ions and to elucidate the local mechanisms underlying the global structural response. While density functional theory (DFT) offers a robust and accurate framework for such calculations, its computational cost limits its applicability for large-scale screening of diverse intercalation structures and sites. In this work, we present a workflow designed to prioritize candidate materials for subsequent detailed characterization. The workflow calculates the volume change upon intercalation using atomic-level features and a machine-learning model for bond-length prediction. The bond-length predictions are based on the assumption that bonds between the same ionic species in similar local coordination environments exhibit comparable lengths across different crystallographic structures. The model was trained on a DFT-generated
dataset, which inherently defines the chemical space in which reliable predictions can be expected. We demonstrate the workflow's utility by screening approximately 1,175,000 transition-metal
oxides and fluorides, followed by DFT validation of the most promising candidates. The proposed workflow enables filtering of large candidate sets and accelerates the potential discovery of low volume change intercalation materials for batteries.
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All authors Aljoscha Felix Baumann, Daniel Mutter, Daniel F. Urban, Christian Elsässer
Strongly Correlated Electrons
Theory of Many-Body Multipole Operators in Single-Centered Electron Systems: Two-Body Toroidal Monopoles in Spinless Orbitals
Shingo Kuniyoshi, Rikuto Oiwa and Satoru Hayami
One-body multipole operators are defined as irreducible representations of rotational
symmetry together with spatial-inversion and time-reversal
symmetries, providing a systematic framework for classifying electronic internal degrees of freedom and for describing a wide variety of composite order parameters. While this formalism has been successfully established for the one-body operator space, a systematic classification of the many-body operator space, especially in interacting systems, remains an open challenge. In this paper, we extend the multipole formalism in the one-body operator space to the many-body operator space. By formulating fermionic creation and annihilation operators as spherical tensors and employing Clebsch-Gordan coupling combined with the exterior (Grassmann)
algebra, we construct an irreducible decomposition of many-body operators that fully incorporates fermionic antisymmetrization. As a concrete application, we classify monopoles appearing in spinless many-body operators. In particular, we show that the electric toroidal monopole, a pseudoscalar breaking spatial-inversion
symmetry, and the
magnetic toroidal monopole, a time reversal-odd scalar, become active in spinless interacting many-body systems, although they are absent in the spinless one-body hybrid orbital space.
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Other Condensed Matter
Topological Tunneling Magnetoresistance Driven by Type-II Weyl-Like States in the Room-Temperature Half-Metal Mn2PC Monolayer
Wei Ma, Yu-Ting Wang, Wen-Bo Sun et al. (+5 more)
We predict the tetragonal Mn2PC monolayer to be a room-temperature
ferromagnetic half-metal with a Curie temperature of 554 K. The
spin-up channel hosts type-II Weyl-like crossings at the
Fermi level with highly anisotropic band dispersion, whereas the
spin-down channel is a wide-gap
semiconductor. Topological edge states obtained from tight-binding calculations confirm the non-trivial bulk
topology.
Spin-orbit coupling opens a small gap of 11.2 meV at the Weyl-like crossings, generating pronounced Berry
curvature and a sizable anomalous
Hall conductivity near the
Fermi level. Based on these properties, we propose topological tunneling magnetoresistance in a Mn2PC-based
magnetic tunnel junction: the parallel configuration conducts through fully
spin-polarized Weyl-like carriers, while the antiparallel configuration is suppressed by the half-metallic gap, yielding a
giant magnetoresistance ratio. The concurrent anomalous
Hall effect in the conducting state provides an experimentally accessible signature of the topological carriers. These results identify the Mn2PC monolayer as a promising platform for room-temperature topological spintronic devices.
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All authors Wei Ma, Yu-Ting Wang, Wen-Bo Sun, Zhiheng Lv, Shuai Shi, Jian-Hong Rong, Tie-Lei Song, Zhi-Feng Liu
Materials Science
Tuning of anomalous magnetotransport properties in half-Heusler topological semimetal GdPtBi
Orest Pavlosiuk, Piotr Wiśniewski, Romain Grasset et al. (+3 more)
Half-Heusler compounds from the $RE$PtBi family exemplify Weyl semimetals in which external
magnetic field induce Weyl nodes. These materials exceptionally host topologically non-trivial states near the
Fermi level and their manifestation can be clearly seen in the magnetotransport properties. In this study, we tune the
Fermi level of the archetypal half-Heusler Weyl semimetal GdPtBi through high-energy electron irradiation, moving it away from the Weyl nodes to investigate the resilience of the contribution of topologically non-trivial states to magnetotransport properties. Remarkably, we observe that the negative longitudinal magnetoresistance, which is a definitive indicator of the
chiral magnetic anomaly occurring in topological semimetals, persists even when the
Fermi level is shifted by 100\,meV from its original position in the pristine sample. Additionally, the anomalous
Hall effect shows complex variations as the
Fermi level is altered, attributed to the energy-dependent nature of the Berry
curvature, which arises from avoided band crossing. Our findings show the robust influence of Weyl nodes on the magneto-transport properties of GdPtBi, irrespective of the
Fermi level position, a behaviour likely applicable to many half-Heusler Weyl semimetals.
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All authors Orest Pavlosiuk, Piotr Wiśniewski, Romain Grasset, Marcin Konczykowski, Andrzej Ptok, Dariusz Kaczorowski
Strongly Correlated Electrons
Formulation of intrinsic nonlinear thermal conductivity for bosonic systems using quantum kinetic equation
Aoi Kuwabara and Joji Nasu
Nonlinear responses in transport phenomena have attracted significant
attention because they can arise even when linear responses are forbidden by
symmetry, with the
quantum geometry of Bloch wave functions playing an essential role. While such effects have been extensively studied in electric transport, similar
quantum-
geometric mechanisms are also expected to govern nonlinear thermal transport. In particular, thermal responses are crucial in bosonic systems such as
magnons and
phonons, which are charge-neutral quasiparticles. However, a consistent theoretical description of nonlinear thermal transport remains challenging because of the difficulty in the treatment of energy magnetization in higher-order responses with Luttinger's gravitational potential method. Here, we formulate the intrinsic nonlinear thermal conductivity of bosonic systems using a
quantum kinetic equation approach that avoids Luttinger's method and naturally incorporates contributions from energy magnetization. We identify three distinct contributions to the nonlinear thermal conductivity: two expressed in terms of
quantum-
geometric quantities, namely the
quantum metric and the thermal Berry-connection polarizability (TBCP), and a third determined solely by the band dispersions. Applying our formalism to a specific
quantum spin model within linear
spin-wave theory, we show that the TBCP term dominates the nonlinear thermal
Hall effect in the absence of threefold
symmetry. Our results differ quantitatively from those obtained using semiclassical theory, thereby highlighting the importance of
quantum corrections beyond the semiclassical picture. These findings establish a general framework for intrinsic nonlinear thermal responses in bosonic systems and reveal
quantum-
geometric mechanisms underlying thermal transport beyond linear response theory.
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Strongly Correlated Electrons
Observation of Kondo hybridization wave in UTe2
Xin Yu, Shuikang Yu, Zheyu Wu et al. (+9 more)
Condensed matter systems with strong electronic correlations often manifest a variety of intertwined ordered phases of charge,
spin, orbital and other degrees of freedom. As a prototypical strongly correlated electronic system, the Kondo
lattice provides fertile soil for many fascinating
quantum states, including
quantum criticality, unconventional superconductivity, hidden order and topological Kondo
insulator/semimetal. The foundation of Kondo physics lies in the hybridization between localized moments and itinerant electrons. Generally, the
evolution of Kondo hybridization is characterized as a broad crossover rather than a phase transition. Thus far, an ordered hybridization phase has not been observed. Here, we use scanning tunneling microscopy (STM) to identify a translational-
symmetry-breaking order of Kondo hybridization wave(KHW) for the first time on the surface of the
spin-triplet heavy-
fermion superconductor UTe2. The unprecedented phase of KHW manifests as a periodically modulated Fano
lattice, accompanied by a commensurate charge density wave (CDW) and a pronounced energy gap opening near the
Fermi level. This KHW-imprinted CDW has an intriguing real-space texture of complementary occupation of the heavy f and conduction charges, thereby forming a Kondo superlattice. The KHW is coexistent with superconductivity in UTe2, which may provide valuable insight into its controversial
spin-triplet pairing
symmetry and the underlying mechanism. Our first experimental evidence for an ordered hybridization state potentially sheds new light on the strong correlation physics of Kondo
lattice system.
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All authors Xin Yu, Shuikang Yu, Zheyu Wu, Alexander G. Eaton, Andrej Cabala, Michal Vališka, Jun Li, Rui Zhou, Yi-feng Yang, Zhenyu Wang, Peijie Sun, Rui Wu