Materials Science
Quantitative Analysis of Light Induced Ion Segregation in Mixed-Halide Perovskites
Petr Machovec, Lukáš Horák, Milan Dopita et al. (+4 more)
Mixed-halide perovskites (MHPs) offer good band gap tunability by stoichiometry changes, which is an essential property for the creation of multijunction
solar cells. However, under illumination, halide ions in MHP segregate and create I- and Br-rich regions, which decreases the efficiency of potential
solar cells. In this work, a method for a detailed investigation of the distribution of halide ions within the MHP during and after illumination is introduced. Calculations of the strain field created by the halide segregation were performed, and the obtained local displacement of atoms was used to calculate the x-ray diffuse scattering. By fitting the experimental data measured on the thin polycrystalline layer of FA0.83Cs0.17Pb(I0.6Br0.4)3 the distribution of Br- and I- ions within an illuminated MHP was determined and the subsequent relaxation process of the segregation in the dark was tracked. Creation of highly Br-rich regions within slightly I-rich volume during the illumination was observed.
Read the full abstract ▾
All authors Petr Machovec, Lukáš Horák, Milan Dopita, Neda Neykova, Lucie Landová, Jakub Holovský, Václav Holý
Statistical Mechanics · Cross-listed from quant-ph
Genuine and Non-Genuine Quantum Non-Markovianity: A Unified Information-Theoretic Review
Rajeev Gangwar and Ujjwal Sen
Understanding whether the features of open
quantum dynamics are genuinely
quantum remains a central challenge in
quantum dynamics. Even though the non-Markovian behavior of
quantum dynamics has been widely investigated across different settings, there is still no consensus on which properties of a dynamics reflect genuine
quantum features and which arise from classical or non-genuine
quantum sources. In this review, we provide detailed information on recent developments in characterizing
quantum non-Markovianity based on information backflow and the nature of its origin. We also present a survey on how various approaches separate classical and
quantum contributions, as well as how they define operational tasks that reveal genuine
quantum non-Markovianity. We analyze several frameworks, including state-distinguishability -based, channel-based (“CP-divisibility”), and process-tensor methods. For each framework, we outline the underlying physical motivation, the criteria proposed to distinguish genuine
quantum non-Markovianity from practical or apparent
memory effects. We further compare different approaches and their strengths and limitations. The review aims to clarify the conceptual and operational aspects of
quantum non-Markovian processes based on their nature and to provide a foundation for future research on
quantum non-Markovianity and its role in advancing
quantum information science and technology.
Read the full abstract ▾
Quantum Gases · Cross-listed from physics.atom-ph
Quantum engineering with ultracold polar molecules using trap-induced resonances
Sakthikumaran Ravichandran, Piotr Kulik and Krzysztof Jachymski
Polar molecules represent a promising platform for
quantum simulation and computation protocols. Highly controllable arrays of optical tweezers are now accessible in experiments, allowing for unprecedented control of individual molecules. Motional dephasing is typically seen as an obstacle in
quantum computing scenarios. Here, we instead consider using the trap structure as a resource for implementing efficient
quantum gates. By numerically solving the two-body problem of dipoles trapped in separate tweezers, we identify trap-induced resonances that can serve as the mechanism for achieving state-dependent dynamics and can be further utilized for
quantum sensing.
Read the full abstract ▾
Materials Science
Intrinsically ultralow thermal conductivity in all-inorganic superatomic bulk crystals
Mingzhang Yang, Yuxi Wang, Jun Deng et al. (+7 more)
Superatomic compounds, composed of atomic clusters interwoven by weak chemical bonds exhibit large anharmonicity vibrations, are excellent candidates for ultralow thermal conductivity (ąppa}) materials. However, growing bulk superatomic single
crystals is challenging due to complex chemical composition and chemical bonds, and studies on their intrinsic thermal property are scarce. Here, we grew high-quality superatomic single
crystals of Re6Se8Te7 and Re6Te15, both of which are narrow band gap
semiconductors that change into metals under external physical pressure. At room-temperature, the ąppa} are 0.32 W m-1 K-1 and 0.53 W m-1 K-1 in Re6Se8Te7 and Re6Te15, respectively, ranking among the lowest value reported in all-inorganic bulk
crystals. It is mainly attributed to the large Grüneisen parameter (1.93) and low average sound speed (< 1482 m/s), which are due to soft Te7 nets weakly embedded among the rigid Re6Se8 (Re6Te8) quasi-cubic clusters. The appearance of
boson peak, i. e., hump of C(T)/T3, verifies the existence of disordered
phonon transports. Besides, the temperature dependence of ąppa} can be described by classic Debye-Callaway model. Notably, above 350 K, the ąppa} values of Re6Se8Te7 and Re6Te15 are remarkably close to the upper limit derived from glassy-like
diffusion model. This finding sets the superatomic compounds as a promising family for searching ultralow-ąppa} and energy management materials.
Read the full abstract ▾
All authors Mingzhang Yang, Yuxi Wang, Jun Deng, Tianping Ying, Qinghua Zhang, Nianjie Liang, Xiaobing Liu, Bai Song, Jian-gang Guo, Xiaolong Chen
Quantum Gases
Resonant two-cluster scattering in a quasi-one-dimensional Bose gas
Tomohiro Tanaka and Yusuke Nishida
We investigate two-cluster scattering in a quasi-one-dimensional Bose gas. We focus on the effective three-body interaction induced by transverse confinement, which is the leading term for breaking integrability in the quasi-one-dimensional setting. Exploiting the Lüscher formula and the integrability of the Lieb-Liniger Bose gas, we find a finite and positive scattering length for elastic two-cluster scattering. The resulting scattering lengths indicate the emergence of a resonance.
Read the full abstract ▾
Strongly Correlated Electrons
Exact $\mathbb{Z}_2$ electromagnetic duality of $\mathbb{Z}_2$ toric code is non-Clifford
Ryohei Kobayashi
The 2D $\mathbb{Z}_2$ toric code admits a global
symmetry exchanging electric and
magnetic quasiparticles, known as electromagnetic duality. Known realizations include
lattice translation
symmetry, an exact $\mathbb{Z}_4$
symmetry generated by a Clifford
circuit, and an exact $\mathbb{Z}_2$
symmetry generated by a non-Clifford
circuit. We show that a Clifford electromagnetic duality cannot realize an exact internal $\mathbb{Z}_2$
symmetry. This is proved rigorously for
symmetries with coarse translation invariance by $l$
lattice units for generic odd $l$. Therefore an exact internal $\mathbb{Z}_2$ electromagnetic duality must be non-Clifford, whereas generic internal Clifford realization necessarily has $\mathbb{Z}_{2^m}$
algebra with $m\ge 2$. Our result suggests an unexpected connection between the
algebra of exact electromagnetic duality and Clifford hierarchy of
circuits.
Read the full abstract ▾
Materials Science
Grain boundary defects induced Tc increment in MnSi
Adrian Benedit-Cardenas, Tobias Fox, Stéphanie Bruyère et al. (+6 more)
The rapid advancement of digital technologies necessitates significant progress in functional materials, which are often derived from scarce elements and involve complex manufacturing processes. Additionally, the trend towards miniaturization in high-tech devices has heightened the demand for extremely small components with tailored functionalities. In the domains of
ferromagnetic materials, the
market is mostly dominated by rare-earth elements-based structures, which are also limited in abundance. In this work, we focus on the microstructure and properties of MnSi. It is a
ferromagnetic material with a relatively low Curie temperature (TC) of 30 K. However, our study demonstrates that Tc can be increased by a factor of 4 through careful control of the
crystal size. MnSi thin films were synthesized by combining two non-
equilibrium techniques: magnetron sputtering and
laser annealing.
Laser annealing provoked the crystallinity
evolution, by heat accumulation, of the barely crystallized films deposited by magnetron sputtering. The
laser beam scanning parameters were adjusted to achieve different fluence values, pulse numbers, and pulse frequencies at each point of the film. Films with a
crystal size of around 20 nm exhibited a TC of up to 120 K. These properties were obtained under conditions of low fluence and a high number pulse. Local
laser impacts were applied to as-deposited samples, enabling spatially controlled crystallization. The interface between the poorly and well-crystallized regions was showcased using high-resolution transmission electron microscopy (HR-TEM). A spatial resolution of approximately 100 {\mu}m was achieved. These results demonstrate the strong potential of
laser annealing as a versatile and promising approach for the fabrication of miniaturized devices.
Read the full abstract ▾
All authors Adrian Benedit-Cardenas, Tobias Fox, Stéphanie Bruyère, Christoph Pauly, Flavio Soldera, Sylvie Migot, Frank Mücklich, David Horwat, Alexandre Nominé
Strongly Correlated Electrons
Tomonaga-Luttinger liquid and charge-density wave in a quasi-one-dimensional material
Jing Li, Guo-Wei Yang, Bai-Zhuo Li et al. (+18 more)
In one-dimensional (1D) electron systems, the
Fermi liquid state breaks down due either to electron interactions, which results in a Tomonaga-Luttinger
liquid (TLL) state, or to Peierls instability, which leads to an insulating charge-density-wave (CDW) phase. In general, these two phenomena are mutually exclusive, and their coexistence remains elusive in real materials. Here, we report the discovery of a new quasi-1D material, Cs$_{1-\delta}$Cr$_3$S$_3$, which unexpectedly exhibits coexistence of the antithetical CDW and TLL states. The CDW state is evidenced by the intra-unit-
cell dimerization, and the opening of an optical band gap of $\sim$250 meV. Meanwhile, TLL behaviour is unambiguously demonstrated by the measurements of electrical transport and angle-resolved photoemission spectroscopy, which reveal a power-law scaling with temperature, bias voltage and electron energy. Band structure calculations reveal isolated, linearly dispersive, 1D bands around the
Fermi level. For the dimerized CDW phase, the 1D
Fermi-surface sheets located at the boundary of the Brillouin zone are gapped from intra-unit-
cell bond
symmetry breaking. Experimentally, subtle Cs vacancies shift the
Fermi level into the linearly dispersive valence band, enabling the observation of TLL behaviour without interrupting the CDW order. This work establishes Cs$_{1-\delta}$Cr$_3$S$_3$ as a rare material platform in which the antagonistic
Fermi-
liquid instabilities coexist and intertwine, opening new avenues for studying emergent
quantum phenomena in 1D systems.
Read the full abstract ▾
All authors Jing Li, Guo-Wei Yang, Bai-Zhuo Li, Yi Liu, Si-Qi Wu, Ji-Yong Liu, Jin-Ke Bao, Xiaoxian Yan, Hua-Xun Li, Jia-Xin Li, Jia-Lu Wang, Yun-Lei Sun, Yi-Ming Lu, Jia-Yi Lu, Yi-Qiang Lin, Hui Xing, Chao Cao, Hao Jiang, Yang Liu, Guang-Han Cao, Hai-Qing Lin
Materials Science
Maskless Electron Beam-Induced Etching of Diamond in Air: A Secondary Electron-Driven Mechanism
Duc-Duy Tran, Cedric Mannequin, Fabrice Donatini et al. (+2 more)
We report a direct, maskless electron beam-induced etching (EBIE) process for diamond in air, enabling high-precision patterning without lithography or
plasma processing. Through a comprehensive analysis of electron-gas, electron-diamond, and gas-surface interactions in the SEM environment, we demonstrate that etching is predominantly governed by low-energy secondary electrons, which drive gas dissociation and radical generation. The resulting oxygen- and nitrogen-based radicals chemisorb on the diamond surface, form volatile carbon-containing species, and desorb under continued electron irradiation, enabling controlled material removal. The process exhibits two distinct regimes: a molecule-limited regime governed by gas flux and an electron-limited regime controlled by current density. Etch depths up to 212 nm and lateral resolution down to 200 nm are achieved. Time-dependent anisotropy is observed, with (100) surfaces transitioning to (111)-faceted morphologies, enhancing etch yield. These results establish a general secondary electron-driven mechanism for EBIE in gas environments, providing a maskless, damage-free nanofabrication route for diamond
semiconductor and other chemically inert materials.
Read the full abstract ▾
All authors Duc-Duy Tran, Cedric Mannequin, Fabrice Donatini, Masahiro Sasaki, Etienne Gheeraert
Materials Science
Hematite Thin Films Grown on Z-Cut and Y-Cut Lithium Niobate Piezoelectric Substrates by Pulsed Laser Deposition
Maximilian Mihm, Stephan Glamsch, Christian Holzmann et al. (+3 more)
Altermagnets are a newly identified class of materials that combine advantageous characteristics of both ferro- and antiferromagnets, making them highly promising for spintronic applications. Hematite has recently been identified as an altermagnetic material and exhibits several noteworthy properties, including a high Néel temperature, a temperature dependent
spin reorientation transition (SRT) at the Morin temperature ($T_\mathrm{M}$), and low
magnetic damping. In this work, we demonstrate the epitaxial growth of hematite thin films on y- and z-cut lithium niobate (LiNbO$_3$) substrates using pulsed
laser deposition (PLD). LiNbO$_3$ as piezoelectric substrate is of particular interest as it enables the efficient excitation of surface acoustic waves (SAWs) with interdigital transducers. The different substrate cuts allow for different orientations of the Néel vector. Films grown on y-cut LiNbO3 are single-crystalline and single-phase, while those deposited on z-cut LiNbO$_3$ exhibit two distinct in-plane (ip) domains rotated 60{\deg} relative to each other. On both substrates, the hematite thin films exhibit a temperature dependent SRT which allows the
antiferromagnetic Néel vector to be controlled. This study paves the way for the development of high-quality piezoelectric/altermagnetic hyprids for magnonics and spintronics.
Read the full abstract ▾
All authors Maximilian Mihm, Stephan Glamsch, Christian Holzmann, Matthias Küß, Helmut Karl, Manfred Albrecht
Soft Condensed Matter
Colloidal phoresis in two-dimensional odd fluids
Yuxing Jiao, Qing Yang and Mingcheng Yang
Under a thermodynamic gradient, for example, the concentration or temperature gradients, the colloidal particles immersed in the solvent can exhibit a directional migration along or against the gradient—phoresis, a cross transport effect. When the solvent is an odd fluid, where the time-reversal and parity
symmetries are broken microscopically, the odd transport phenomenon is allowed. This means an odd phoresis may appear: the colloidal particle migrates perpendicularly to the thermodynamic gradient. Here, we realize the odd diffusiophoresis and odd thermophoresis for a colloidal particle immersed in a two-dimensional odd fluid by performing mesoscale fluid simulations. We quantify the odd phoretic factors and further provide the phoresis-osmotic flow field driven by a phoretic colloidal particle, which is quantitatively consistent with the numerical solutions of the corresponding odd fluid dynamics equations.
Read the full abstract ▾
Strongly Correlated Electrons
Spontaneously formed excitonic density wave with vortex-antivortex lattice in twisted semiconductor bilayers
Deguang Wu, Yiran Xue, Baigeng Wang et al. (+2 more)
Exciton condensation, characterized by uniform phase coherence across macroscopic length scales, has enabled the discovery of a variety of excitonic states, greatly enriching our understanding of correlated many-body physics. More exotic
quantum phenomena are anticipated when the phase factor develops spatial dependence. However, whether excitonic condensates with spatially modulated phase profiles can emerge spontaneously remains an open question. In this work, we uncover novel forms of excitonic density waves featuring nontrivial phase patterns in twisted
semiconductor bilayers. Remarkably, we show that kinetic frustration inherent to these systems stabilizes excitonic condensates arranged into a
vortex-antivortex
lattice. This represents a class of correlated states previously unknown in two-dimensional
semiconductors, wherein the phase degrees of freedom of
exciton condensates play a defining role. Such states spontaneously break both time-reversal and inversion
symmetries, leading to non-reciprocal
exciton transport, an effect we term the excitonic diode effect. Furthermore, we compute and identify characteristic
impurity-induced states in these unconventional condensates, providing distinct signatures for their experimental detection.
Read the full abstract ▾
All authors Deguang Wu, Yiran Xue, Baigeng Wang, Rui Wang, D. Y. Xing
Materials Science · Cross-listed from cs.CE
An efficient open-source framework for high-fidelity 3D surface topography and roughness prediction in milling
Hadi Bakhshan, Sima Farshbaf, Adrián Travieso-Disotuar et al. (+3 more)
With the emergence of data-driven approaches in science, there is growing interest in their application to manufacturing, particularly in surface precision engineering. However, generating large
datasets required for model training is often impractical experimentally due to high costs and the time-intensive nature of measurements. High-fidelity synthetic
datasets offer a viable alternative if they can be generated both efficiently and accurately. To address this challenge, this paper presents an efficient framework for generating accurate 3D surface topographies and roughness indicators in milling operations using numerical methods. First, a conventional topography prediction model is developed based on the forward solution method (FSM). Building on this, an optimized computational
algorithm is proposed to establish an efficient FSM with significantly improved performance. The model is validated against two independent sets of experimental results, assessing both prediction accuracy and computational efficiency. The results demonstrate acceptable prediction errors and an average computational speedup of 42.2x. The proposed open-source model provides a generalizable framework for large-scale analysis, enabling the generation of extensive
datasets for data-driven surrogate modeling.
Read the full abstract ▾
All authors Hadi Bakhshan, Sima Farshbaf, Adrián Travieso-Disotuar, Luciano Mijaíl Villarreal, Fernando Rastellini Canela, Josep Maria Carbonell
Disordered Systems and Neural Networks
Arbitrarily Configurable Wavefunctions via Imaginary Gauge Phase Imprint in Non-Hermitian Lattices
Ji-Long Dong, Shi-Liang Zhu and Dan-Wei Zhang
We propose a general framework, termed the imaginary gauge phase imprint (IGPI), which enables engineering arbitrarily configurable wavefunctions with exact solutions and self-organization dynamics in any-dimensional non-Hermitian
lattices under imaginary gauge fields. Using this method, we uncover a novel phase with exact critical wavefunctions, dubbed the skin critical phase (SCP), which is marked by unconventional localization, topological-skin, and dynamical characteristics. Furthermore, we validate the IGPI by imprinting and visualizing complex fractal states with Sierpinski-carpet and Koch-snowflake profiles, as well as exotic super-moire and 3D-moire states in regular
lattices. Our work not only offers fresh insights into non-Hermitian critical and fractal physics, but also provides a rigorous paradigm for controlling and visualizing wavefunction patterns using the IGPI in engineered non-Hermitian systems.
Read the full abstract ▾
Strongly Correlated Electrons
Tilted and Twisted Magnetic Moments in the Kitaev Magnet $\alpha$-RuCl$_3$
Xiao Wang, Fengfeng Zhu, Markus Braden et al. (+8 more)
The layered honeycomb magnet $\alpha$-RuCl$_3$ has attracted intense scrutiny as a
prime candidate for realizing the Kitaev
quantum spin liquid, yet a consensus on its microscopic
Hamiltonian remains elusive due to the material's extreme sensitivity to structural details. Here, we report a comprehensive reexamination of the low-temperature crystallographic and
magnetic structures of high-quality $\alpha$-RuCl$_3$ single
crystals using unpolarized and polarized
neutron diffraction. We confirm a sharp, first-order structural phase transition to the rhombohedral $R\bar{3}$ space group with a pronounced thermal hysteresis. Crucially, using both spherical and longitudinal
neutron polarization analysis, we determine the 3D orientation of the ordered
magnetic moment without the ambiguity typically arising from domain distributions. We find that the Ru$^{3+}$
magnetic moments in the zigzag phase are tilted by $15.7^\circ$ out of the hexagonal plane and, remarkably, exhibit an additional in-plane twist of $-13.8^\circ$. This "tilted and twisted" geometry differentiates the ground state from the previously reported models based on unpolarized
neutron diffraction or resonant elastic X-ray scattering (REXS) analysis.
Read the full abstract ▾
All authors Xiao Wang, Fengfeng Zhu, Markus Braden, Karin Schmalzl, Wolfgang Schmidt, Martin Meven, Erxi Feng, Yinghao Zhu, Alexandre Bertin, Paul Steffens, Yixi Su
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
The role of focused laser plasmonics in shaping SERS spectra of molecules on nanostructured surfaces
Fran Nekvapil and Cosmin Farcău
The dependence of surface-enhanced Raman scattering (SERS) spectra on the precise axial position of the
laser focus relative to a solid nanostructured substrate has received little to no
attention in the literature. Here we show this dependence is both real and physically meaningful. Through vertical (Z-axis) scans varying the distance between the
laser focus and a planar SERS substrate, we find that the SERS signal intensity follows a Lorentzian axial profile that peaks consistently above the physical sample surface. More significantly, the relative intensities of different spectral regions, i.e. SERS bands and background, vary non-monotonically and non-uniformly along the Z axis, meaning that band intensity ratios are focus-dependent. Finite-Difference Time-Domain (FDTD) simulations attribute these effects to plasmonic near-field responses specific to the focused and defocused beam interacting with the nanostructured metal surface. These findings reveal a previously overlooked source of spectral distortion in solid-substrate SERS measurements, with direct implications for the design and interpretation of quantitative assays based on band intensity ratios.
Read the full abstract ▾
Materials Science
Quantification of magnetic interactions in van der Waals heterostructures using Lorentz transmission electron microscopy and electron holography
Joachim Dahl Thomsen, Qianqian Lan, Nikolai S. Kiselev et al. (+4 more)
Magnetic van der Waals (vdW) materials are promising for
memory and logic applications because of their highly tunable
magnetic properties and compatibility with vdW
heterostructure devices. However, coupling between
magnetic textures in stacked layers is difficult to resolve in conventional plan-view measurements because the
magnetic signal is integrated over the sample thickness. Here, these interactions are quantified in Fe$_3$GeTe$_2$ (FGT)/graphite/FGT
heterostructures using cross-sectional Lorentz transmission electron microscopy and off-axis electron holography, enabling reconstruction of the local
magnetic induction within and between the layers. Domain
alignment weakens with increasing FGT separation, yielding a stray-field coupling length scale of $\lambda = 37 \pm 7$ nm for the cross-sectional geometry studied here, corresponding to the average separation at which domain misalignment first emerges. This length scale corresponds to an approximately 23% reduction in the interlayer
magnetic induction relative to bulk FGT. Surface effects result in a reduced
magnetic induction compared to bulk FGT up to $\sim$100 nm from a surface. Comparisons of experimental data with model-based iterative reconstructions of the magnetization and micromagnetic simulations shows that the reduction in induction near surfaces is due to demagnetizing and stray fields. These results quantify the
magnetic induction in stacked vdW magnets and guide the design of devices that require controllable coupling between
magnetic textures.
Read the full abstract ▾
All authors Joachim Dahl Thomsen, Qianqian Lan, Nikolai S. Kiselev, Eva Duft, Arslan Rehmat, Zdeněk Sofer, Rafal E. Dunin-Borkowski
Materials Science · Cross-listed from physics.optics
Dirac branch-cut modes with relativistic transport
Bofeng Zhu, Chengzhi Ma, Qiang Wang et al. (+6 more)
Emergent Dirac fields, exhibiting effective relativistic physics, are most commonly associated with bulk and surface states in materials such as
graphene and topological
insulators. Here we show that phase dislocations of a complex Dirac mass support a distinct family of propagating Dirac defect states that behave as massless or massive one-dimensional relativistic modes. These traveling-wave defect states, termed Dirac branch-cut (DBC) modes, are governed by a one-dimensional Dirac
Hamiltonian whose effective mass is controlled by the phase difference across the branch cut. Using acoustic metamaterials, we experimentally demonstrate a range of relativistic phenomena exhibited by DBC modes, including relativistic dispersion, energy-independent confinement, Klein tunnelling, and transport along freeform (e.g., spiral) trajectories. Our results establish branch-cut defects as a distinct platform for realizing propagating Dirac defect states, extending relativistic Dirac physics from bulk and surface states to propagating modes confined to defect boundaries.
Read the full abstract ▾
All authors Bofeng Zhu, Chengzhi Ma, Qiang Wang, Gui-Geng Liu, Xiuhai Zhang, Zheyu Cheng, Qi Jie Wang, Baile Zhang, Y. D. Chong
Strongly Correlated Electrons
Quantum-Coherent Regime of Programmable Dipolar Spin Ice
Krzysztof Giergiel and Piotr Surówka
Frustrated
spin-ice systems support emergent gauge fields and fractionalized quasiparticles that act as
magnetic monopoles. Although artificial platforms have enabled their direct visualization, access to their
quantum-coherent dynamics has remained limited. Here we realize a programmable dipolar square
spin-ice model using a superconducting-
qubit quantum annealer, providing access to a previously unexplored
quantum-coherent regime of artificial
spin ice. By implementing a direct one-to-one mapping between
lattice spins and physical
qubits, together with engineered extended couplings, we realize effective dipolar interactions on frustrated
lattices comprising more than 400 vertices. Tuning transverse-field fluctuations enables us to probe the real-time dynamics of Dirac-string defects and interacting monopole
plasmas. We observe super-diffusive monopole transport, with scaling exponents intermediate between classical
diffusion and ballistic motion, indicating dynamics beyond classical
stochastic relaxation and consistent with coherent propagation within an emergent gauge
manifold. These results establish programmable
quantum spin ice as a scalable platform for investigating fractionalized excitations and emergent gauge dynamics in engineered
quantum matter.
Read the full abstract ▾
Disordered Systems and Neural Networks · Cross-listed from quant-ph
Adiabatic dressing of quantum enhanced Markov chains
Wen Ting Hsieh, Alev Orfi and Dries Sels
Quantum-enhanced Markov chain Monte Carlo, a hybrid
quantum-classical
algorithm in which configurations are proposed by a
quantum proposer and accepted or rejected by a classical
algorithm, has been introduced as a possible method for robust
quantum speedup. Previous work has identified competing factors that limit the
algorithm's performance: the
quantum dynamics should delocalize the system across a range of classical states to propose configurations beyond the reach of simple classical updates, whereas excessive delocalization produces configurations unlikely to be accepted, slowing the chain's convergence. Here, we show that controlling the degree of delocalization by adiabatically dressing the quench protocol can significantly enhance the Markov gap in paradigmatic
spin-glass models.
Read the full abstract ▾
Materials Science
Orbitronics: orbit-spin interconversions for long range orbital propagation enabled by spin current
Melissa Yactayo, A. Pezo, J. L. Ampuero et al. (+9 more)
Orbitronics assumes long-range orbital currents, like
spin currents in spintronics. However, recent theories and experiments challenge this view, showing rather local characters for orbital polarization and importance of orbit-
spin conversions. In our work, angular momentum is created by
ferromagnetic resonance or thermal gradients in Ni/(Pt)Ti/Au
heterostructures and detected by conversion to charge current. The observed charge currents are independent of Ti thickness up to 60 nm, which is incompatible with orbital transport and Orbital
Hall Effect in Ti. Instead, they depend on both Ti interfaces, evidencing
spin-mediated transport in between after and before local orbit-
spin interconversions.
Read the full abstract ▾
All authors Melissa Yactayo, A. Pezo, J. L. Ampuero, M. Tian, L. Badie, J. Quispe-Marcatoma, C. V. Landauro, Y. Xu, Sébastien Petit-Watelot, Michel Hehn, A. Fert, J.-C. Rojas-Sánchez
Mesoscale and Nanoscale Physics
Dynamical diffraction formalism for imaging time-dependent diffuse scattering from coherent phonons with Dark-Field X-ray Microscopy
Darshan Chalise, Brinthan Kanesalingam, Dorian P. Luccioni et al. (+3 more)
Coherent acoustic
phonons, whose damping sets the upper bound of quality factors in acoustic resonators, play a critical role in advanced telecommunication and
quantum information technologies. Yet, probing their decay in the GHz regime remains challenging using conventional surface-based techniques. Dark-field X-ray microscopy (DFXM) offers a solution by enabling through-depth, non-destructive and full-field imaging of strain fields and dislocations inside bulk materials with high spatial and angular resolution. We previously used kinematic diffraction theory to describe DFXM signals based on how the Bragg peak shifts due to the strain wave, allowing us to reconstruct the frequency spectrum of coherent
phonons as a function of depth through the sample. The approach of tracking the Bragg peak shifts to study
phonon dynamics, however, places an upper-bound to the highest
phonon frequency that can be studied, determined by the spatial resolution of the measurement. In this work, we discuss how coherent
phonon dynamics can be studied with DFXM from time-dependent intensity oscillation sidebands. This approach simultaneously allows studying coherent
phonon dynamics in real and reciprocal space, overcoming frequency resolution limits imposed by the real-space resolution of Bragg-peak tracking. Using Takagi-Taupin dynamical diffraction formalism, we establish the spatial and reciprocal space resolution achievable for studying the coherent
phonon dynamics and evaluate conditions for observing long-lived intensity oscillations. We close by proposing experimental strategies to optimize excitation bandwidths and reciprocal-space selectivity. The formalism in the paper enables the design of DFXM experiments for quantitative, frequency-resolved measurements of acoustic
phonon decay and
phonon-defect interactions in bulk crystalline materials.
Read the full abstract ▾
All authors Darshan Chalise, Brinthan Kanesalingam, Dorian P. Luccioni, Daniel Schick, Aaron M. Lindenberg, Leora Dresselhaus-Marais
Mesoscale and Nanoscale Physics
Ferromagnetic resonance modulation in topological materials with bulk–boundary coexistence
Shun Muto, Yuya Ominato, Takeo Kato et al. (+2 more)
We extend
ferromagnetic resonance (FMR) modulation theory to describe systems in which bulk and boundary states of topological materials coexist, with both appearing at the same energy. As an application of the formulation, we investigate the enhancement of the Gilbert damping constant on the $(110)$ surface of a $d$-wave
superconductor where nodal quasiparticles coexist with edge states, which are one-dimensional boundary states, known as surface zero-energy Andreev bound states. We find two characteristic features: a pronounced edge-to-edge excitation peak near zero energy, and an additional edge-to-bulk excitation peak at the superconducting gap energy. We also observe power-law decay at low temperatures and exponential decay at intermediate temperatures in the low-energy regime. These features demonstrate the comparable contributions of the bulk and boundary states to the FMR response. Our theory provides a broadly applicable framework for the analysis of topological materials.
Read the full abstract ▾
All authors Shun Muto, Yuya Ominato, Takeo Kato, Mamoru Matsuo, Ai Yamakage
Materials Science
Fractional Modeling of Thermoelastic Fracture Behavior in a Cracked PZT-4 Strip under Transient Thermal Loading
Diksha, Soniya Chaudhary and Pawan Kumar Sharma
This paper investigates the thermoelastic fracture response of a transversely isotropic piezoelectric strip containing a vertical insulated crack under transient thermal shock loading and pre-existing stress fields. The analysis is conducted within the framework of generalized fractional heat conduction using the Ezzat model, which incorporates thermal relaxation and
memory-dependent effects. The problem is formulated as a mixed boundary value problem governed by fractional thermoelastic equations. The Laplace transform technique is employed to obtain temperature and coupled fields in the transform domain. The resulting system of singular integral equations is solved using the Lobatto-Chebyshev collocation method to determine the displacement discontinuity and the associated thermal stress intensity factors at the crack tips. The transient response in the time domain is recovered through numerical inversion of the Laplace transform using the Stehfest
algorithm. Numerical results for PZT-4 are presented to examine the influence of fractional order, thermal relaxation time, pre-existing stresses, and
geometric parameters on temperature distribution, thermoelastic stress fields, and stress intensity factors. The results demonstrate significant deviations from classical
Fourier predictions, revealing wave-like thermal behavior and inherent
memory effects associated with fractional heat conduction. The present formulation establishes a unified framework for the analysis of thermoelastic fracture in piezoelectric ceramics and provides insights into the design and reliability of smart structures operating under severe thermal conditions.
Read the full abstract ▾
Materials Science
Self-Limiting Mechanism of Anti-Stokes Optical Cooling in Diamond NV Centers
Haruki Manaka and Yasuhiro Yamada
Anti-Stokes optical cooling in diamond nitrogen-vacancy (NV) centers is experimentally and numerically investigated. Photoluminescence-excitation spectroscopy reveals pronounced
phonon-assisted anti-Stokes emission under excitation below the zero-
phonon line (ZPL). However, the below-ZPL excitation drives photoinduced charge-state conversion between negatively-charged NV- and neutral NV0, thereby suppressing the NV- mediated cooling channel. Time-resolved photoluminescence (PL) measurements reveal an increase in the effective PL lifetime with excitation density, reflecting an increasing NV0 contribution. By fitting nanosecond and millisecond PL dynamics with a minimal rate-equation model, we extract effective optical pumping and charge-conversion rates, which enables us to quantitatively simulate the cooling performance. The simulations predict a self-limiting behavior of anti-Stokes cooling and clarify the excitation conditions under which net cooling can be sustained within this effective model. The estimated cooling power per NV center is comparable, on a microscopic basis, to values discussed for
semiconductor quantum dots and rare-earth optical coolers. These results identify charge-state conversion as a key bottleneck for defect-based optical refrigeration.
Read the full abstract ▾
Materials Science
A Comparative Study of Molecular Dynamics Approaches for Simulating Ionic Conductivity in Solid Lithium Electrolytes
Dounia Shaaban Kabakibo, Félix Therrien, Yoshua Bengio et al. (+4 more)
Accurate prediction of ionic conductivity is critical for the design of high-performance solid-state electrolytes in next-generation batteries. We
benchmark molecular dynamics (MD) approaches for computing ionic conductivity in 21 lithium solid electrolytes for which experimental ionic conductivity has been previously reported in the literature. In particular, we compare simulations driven by density functional theory (DFT) and by universal machine-learning interatomic potentials (uMLIPs), namely a MACE foundation model. We find comparable performance between DFT and MACE, despite MACE on one GPU more than 350 times faster than DFT on a 64-CPU node. The framework developed here is designed to enable systematic comparisons with additional uMLIPs and fine-tuned models in future work.
Read the full abstract ▾
All authors Dounia Shaaban Kabakibo, Félix Therrien, Yoshua Bengio, Michel Côté, Hongyu Guo, Homin Shin, Alex Hernandez-Garcia
Strongly Correlated Electrons · Cross-listed from physics.comp-ph
Simulation of strongly quantum-degenerate uniform electron gas using the pseudo-fermion method
Yunuo Xiong, Tommaso Morresi and Hongwei Xiong
For strongly
quantum-degenerate systems at finite temperatures, the
fermion sign problem remains the major obstacle to first-principles simulations. In this work, we apply the recently proposed pseudo-
fermion method - designed to overcome the sign problem - to strongly
quantum-degenerate uniform electron gases. We find that the pseudo-
fermion method can efficiently and highly accurately infer the energy of the uniform electron gas while being free from the
fermion sign problem. For example, in the strongly
quantum-degenerate regime where RPIMC fails (33
spin-polarized electrons at the density parameter $r_s = 0.5$), the relative deviation between the pseudo-
fermion method and the exact CPIMC result is only 0.6%. In particular, the pseudo-
fermion method bridges the gap where neither CPIMC nor RPIMC can accurately simulate the regime $1 \le r_s \le 2$ at the reduced temperature $\theta = 0.0625$. This work demonstrates that the pseudo-
fermion method opens a new pathway for studying strongly
quantum-degenerate systems in a sign-problem-free manner.
Read the full abstract ▾
Statistical Mechanics
Trinity of Varentropy: Finiteness, Fluctuations, and Stability in Power-Law Statistics
Hiroki Suyari
Power-law distributions are widely observed in complex systems, yet establishing their thermodynamic consistency remains a theoretical challenge. In this paper, we present a thermodynamic framework for power-law statistics based on the renormalized
entropy $s_{2-q}$. Derived from the asymptotic scaling of the combinatorial $q$-factorial, this quantity yields a stable thermodynamic limit, remaining finite ($O(N^0)$) for systems with strong correlations. Furthermore, we clarify the physical origin of the nonlinearity parameter $q$ through the concept of Varentropy (Variance of
Entropy). By mapping the microscopic combinatorics sequentially onto the probability constraints of Type-B superstatistics, we prove that the entropic index is strictly governed by the exact identity $q-1 = 1/C$, where $C$ is the total thermodynamic heat capacity of the system and the reservoir. This deductive derivation, enforced by the uniqueness of the inverse Laplace transform, demonstrates that power-law statistics emerges as a necessary consequence of finite thermal environments, providing a first-principles description beyond the standard infinite Boltzmann-Gibbs limit ($C \to \infty$).
Read the full abstract ▾
Statistical Mechanics
Scaling of Long-Range Loop-Erased Random Walks
Tianning Xiao, Xianzhi Pan, Zhijie Fan et al. (+1 more)
We study the scaling properties of long-range loop-erased random walks (LR-LERW), where the underlying random walker performs Lévy-flight-like jumps with a power-law step-length distribution $P(\mathbf{r})\sim |\mathbf{r}|^{-(d+\sigma)}$. Using extensive Monte Carlo simulations, we measure the scaling relation $N \sim R^{d_N}$ between the loop-erased step number $N$ and the spatial extent $R$, and determine the
geometric exponent $d_N$ for various values of $\sigma$ in spatial dimensions $d = 1, 2,$ and $3$, as well as at the marginal point $\sigma = 2$ in $d=4$ and $5$. We observe a continuous crossover from long-range (LR) to short-range (SR) behavior as $\sigma$ increases. Below the upper critical dimension $d<d_c=4$, for $\sigma < d/2$, loop erasure is asymptotically irrelevant and $d_N=\sigma$, consistent with Lévy-flight scaling. For $d/2 < \sigma < 2$, loop erasure becomes relevant and $d_N$ varies continuously toward the SR-LERW value. At the marginal points with $\sigma=d/2$ or $\sigma=2$, clear logarithmic corrections are observed. At and above the upper critical dimension, $d \geq 4$, the scaling at $\sigma=2$ is found to be $N \sim R^2/\ln R$, consistent with that of the corresponding Lévy flight. Our results provide a systematic numerical determination of $d_N(\sigma)$ for the LR-LERW across dimensions, and are consistent with $\sigma_* = 2$ as the boundary between LR and SR critical behaviors recently established in a broad variety of statistical models.
Read the full abstract ▾
All authors Tianning Xiao, Xianzhi Pan, Zhijie Fan, Youjin Deng
Materials Science
Graphitic-C3N4/TiO2(B) S-scheme Heterojunctions for Efficient Photocatalytic H2 Production and Organic Pollution Degradation
Xiaoyi Zhou, Min Zhang, Qiushi Wang et al. (+3 more)
Achieving both broad
solar-spectrum absorption and strong redox capability is critical for
semiconductor photocatalysts in environmental remediation and energy conversion. Herein, an S-scheme heterojunction photocatalyst is constructed by coupling TiO2(B) nanorods with g-C3N4 nanosheets. Its well-matched band structure extends light absorption from the UV to the visible region and enables efficient charge separation. Under simulated sunlight irradiation, the 40 wt% g-C3N4/TiO2(B) heterojunction delivers a H2
evolution rate of 1.98 mmol g-1 h-1 for water reduction with methanol as the sacrificial
agent, which is 1.5 and 2.0 times higher than those of pure g-C3N4 and TiO2(B), respectively. When exposed to amoxicillin wastewater instead of methanol solution, the heterojunction degrades 98.2% of amoxicillin and produces 20.70 umol g-1 of H2 within 90 min. Moreover, the heterojunction shows excellent photodegradation activity toward various organic antibiotics and dyes, owing to the S-scheme charge separation mechanism. This work highlights the promising potential of S-scheme heterojunctions for photocatalytic H2 production coupled with organic wastewater treatment.
Read the full abstract ▾
All authors Xiaoyi Zhou, Min Zhang, Qiushi Wang, Shiwen Du, Xuedong Jing, Zhenyi Zhang