Materials Science · Cross-listed from quant-ph
Scientific applications of quantum computing: challenges and opportunities
Bruno Camino, C. Richard A. Catlow, John Buckeridge et al. (+13 more)
The predictive simulation of molecules and materials has had a broad and significant impact. It nevertheless remains constrained by the cost of accurately treating electronic correlation, excited states, and complex energy landscapes.
Quantum computing offers a fundamentally different computational paradigm in which
quantum states are encoded and manipulated directly rather than approximated on classical hardware. Here we discuss where this approach may provide a genuine scientific advantage in chemistry, materials science, and biochemistry. Promising directions include the high-accuracy treatment of correlated active spaces, improved excited-state simulations, and accelerated exploration of combinatorial structure spaces. The central challenge is therefore not
qubit scaling alone, but demonstrably chemically meaningful gains in predictive reliability. We argue that near-term value is most likely to come from disciplined workflow integration rather than wholesale replacement of classical methods. Noisy physical devices, error-mitigated utility experiments, early fault-tolerant devices, and fully fault-tolerant
quantum computers offer different scientific prospects, and claims of usefulness must be tied to the specific regime being discussed.
Quantum computing will become scientifically valuable when it demonstrably reduces uncertainty in computed energies, rates, spectra, or materials stability after the full costs of state preparation, measurement, error handling, and coupling to classical simulation are included.
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All authors Bruno Camino, C. Richard A. Catlow, John Buckeridge, Alin M. Elena, Vladimir V. Gusev, Sarah Harris, Thomas W. Keal, Glenn Jones, Vivien Kendon, Syma Khalid, Phalgun Lolur, Jamal A. Nasir, Matthew J. Rosseinsky, Chris-Kriton Skylaris, Paul A. Warburton, Scott M. Woodley
Statistical Mechanics
Absence of critical scaling in the Schelling segregation model
Mouhssine Rifaki
We find no evidence of critical scaling in the Schelling segregation model, in either the Moore neighborhood or its dense-spectrum extension to Chebyshev radii up to $r_0 = 6$ ($k = 168$ neighbors). On periodic grids up to $L = 320$ with 50 trials per point (> 12,500 runs), every finite-size scaling diagnostic in the Moore baseline fails: the per-$L$ $T_c$ does not drift, Var$(S) \sim L^{-2.02 \pm 0.09}$ matches trivial averaging, $\gamma/\nu \approx 0$, and the scaling collapse never reaches a finite optimum. The 8-site Moore neighborhood restricts satisfaction to ratios $j/k$ with $k \leq 8$, giving $S(T)$ a staircase structure with 23 rational thresholds; discreteness alone does not forbid criticality (cf. the Ising model), but the scaling evidence rules it out empirically. A branching-ratio calculation predicts subcritical cascades of mean size $1/(1-R)$ and is validated by perturbation experiments to within 15%; the multiscalar dissimilarity length stays finite across the transition. The dense-spectrum extension strengthens the negative verdict: across $r_0 \in {3,4,5,6}$ on $L \in {40,80,160}$ the Binder cumulant has no $L$-curve crossing and the per-$L$ $T_c$ drift is monotonic and unsaturated; at $r_0 = 4$, extending to $L = 320$ gives $\alpha = -2.70$, below the critical boundary $\alpha = -2$, dissolving an apparent $\alpha = +0.81$ signal visible only on $L \in {40,80}$. The mechanism is the absence of long-range correlation in
equilibrium plus deterministic high-$k$ dynamics, not the staircase structure. With a Beta-distributed heterogeneous tolerance, the intolerant tail drives segregation even at moderate population-average tolerance. The staircase
theorem and cascade mechanism together account for the Schelling transition without invoking critical phenomena.
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Materials Science
Enhancing Hydrogen Adsorption Ability of MOF-5 with Metal Node Exchange and Linker Functionalisation
Joshua Edzards, Holger-Dietrich Sassnick and Caterina Cocchi
In the search for promising material candidates for hydrogen storage, we investigate from first principles derivatives of metal organic framework 5 (MOF-5), including isoelectronic substitution of the metal centers (Zn $\rightarrow$ Mg, Cd) and linker functionalization with NH$_2$, OH, and NO$_2$ groups. Metal-node substitution consistently stabilises and ligand functionalization systematically enhances H$_2$ binding at the metal-oxo cluster sites. The combination of Cd centers and NO$_2$ groups proves to be most efficient, yielding an adsorption energy of -15.58 kJ mol$^{\text{-1}}$, which substantially outperforms the storage ability of pristine MOF-5. Detailed electronic structure analysis clarifies how the local framework environment coordinates the guest molecule, providing a robust design framework to guide the experimental development of advanced adsorbent materials.
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Strongly Correlated Electrons
Non-invertible Lattice 1-Form Symmetries for Non-Abelian Topological Order
Rafael Flores-Calderón, Frank Pollmann and Michael Knap
Higher-form
symmetries generalize conventional global
symmetries and act on lower-dimensional submanifolds of a
quantum system. While Abelian topological phases can be organized by 1-form
symmetries that form a group, non-Abelian topological phases based on finite groups require 1-form
symmetry operators governed by non-invertible fusion
algebras. In this work, we make this statement precise in
quantum double
lattice models $\mathcal D(G)$ for finite non-Abelian groups $G$. We construct the electric,
magnetic, and dyonic 1-form operators directly at the
lattice fixed point and show that together they form a complete nonlocal diagnostic
algebra for the topological
Hilbert space. Using these operators, we explicitly determine the cylinder and
torus ground-state subspaces for arbitrary finite $G$. Furthermore, we calculate the microscopic fusion and gluing of the 1-form
symmetries and show that their topological deformation properties emerge after projection to the defect-free topological subspace. Our results establish ground states of non-Abelian
quantum double models as a concrete microscopic realization of spontaneous non-invertible 1-form
symmetry breaking and provide an operator
language that may be useful for characterizing such states in
quantum processors.
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Materials Science
Mechanical-microstructural correlation on SPS-fabricated NiTi alloy
Tadeáš Těhan, Jaromír Kopeček, Elizaveta Iaparova et al. (+2 more)
Mechanical properties and dynamical mechanical analysis were performed on compact Spark
Plasma Sinter samples. It has been observed that the sample with less porosity reflects the behavior of superelasticity response. Other samples show failure during first cycles that may be due to porosity. Compaction of metallic powder is one of the standard procedures in the field of powder metallurgy for the fabrication of bulk material. Consolidation of the sample as a function of sintering temperature plays a crucial role in the final compaction mechanism. However, the
evolution of compaction, microstructure, phase transformation and mechanical properties as a function of sintering temperature is hardly disclosed. In this work, a correlation has been established between mechanical and microstructural properties of compact samples. The maximum compactness and the corresponding microstructure, porosity, texture, phase transformation, grain size, hardness, mechanical properties of compact samples were discussed. The research establishes mechanical properties-structure correlations for compaction of NiTi
alloy in advanced engineering applications.
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All authors Tadeáš Těhan, Jaromír Kopeček, Elizaveta Iaparova, Eduardo Alarcón, Sneha Samal
Mesoscale and Nanoscale Physics
Plexciton-mediated Raman scattering in strongly coupled systems
Danyang Liu, Meijuan Sun, Li Chen et al. (+1 more)
A series of experimental results demonstrate a distinctive Raman response in plasmon-
exciton coupled systems. The enhancement of Raman scattering varies for different
phonon modes. We describe the microscopic dynamical process of this Raman scattering using
quantum many-body theory. Unlike conventional Raman scattering involving electron-
phonon interactions, the process in plasmon-
exciton coupled systems is characterized by inelastic scattering between
phonons and plasmon-
exciton polaritons-formed through the coupling of plasmons and
excitons-acting as intermediate states. We derive analytical expressions for the Raman intensity and enhancement factors for various
phonon modes, which show excellent agreement with experimental data. Furthermore, experimental fittings indicate a substantial disparity in the linewidths of the upper and lower polariton branches, for which we provide a comprehensive theoretical explanation. Based on linear response theory, we propose a microscopic mechanism for the formation of plasmon-
exciton polaritons, enabling the analytical calculation of their dispersions and linewidths. This approach naturally accounts for the significantly asymmetry observed in the linewidths of the upper and lower polariton branches. By characterizing the polariton-
phonon scattering process at the
quantum level, we reveal the fundamental physical mechanism driving polariton-enhanced Raman scattering. Our work establishes a universal framework for describing the dynamical
evolution of coupled systems, providing a versatile paradigm for exploring the interactions between plasmons and other quasiparticles.
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All authors Danyang Liu, Meijuan Sun, Li Chen, Hao Shen
Quantum Gases · Cross-listed from hep-th
Effective field equations with stochastic initial conditions
Ian G. Moss
The
evolution of
quantum field expectation values from an initial non-
equilibrium quantum state can be followed numerically using the Truncated Wigner technique. It can track non-perturbative
quantum phenomena, such as false
vacuum decay, in real time with promising results. Nevertheless, it is an approximate method subject to
quantum loop corrections. The extension of Truncated Wigner into a fully fledged effective field equation approach is discussed here, including corrections from higher loops and higher momenta.
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Soft Condensed Matter
Experimental evidence of an Apolar Biaxial Smectic-A Phase Comprised of Bent-Core Molecules
Susovan Bhandary, Abhijith K and Arun Roy
We report structural and physical investigations on the biaxial smectic-A phase exhibited by a compound consisting of asymmetric bent-core molecules. Upon cooling from the isotropic phase, the compound exhibits the following phase sequence: Isotropic (403.9 K) $\rightarrow$ biaxial Smectic-A (359.8 K) $\rightarrow$
Crystal. The polarized optical microscopy, X-ray diffraction, and polarization reversal current measurements clearly establish the biaxial nature of the smectic-A phase without any layer polarization. The measured layer spacing in the entire temperature range of the smectic-A phase is close to the molecular length. The schlieren texture in a homeotropically aligned sample shows both $\pm \frac{1}{2}$ and $\pm 1$ defects which indicate the biaxial nature of this smectic-A phase. The dielectric spectroscopy studies on the samples revealed Debye-type relaxation processes with the relaxation time following the Arrhenius equation with temperature. Interestingly, the observed biaxial smectic-A phase exhibits a remarkable electro-optic response for a planar-aligned sample without any reorganization of the smectic layer structure.
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Disordered Systems and Neural Networks · Cross-listed from hep-lat
Alexander Rothkopf
We construct the natural generalization of
stochastic quantization (in the Markovian sense) by considering jump-
diffusion processes. This class of
stochastic processes exhibits non-continuous paths, so-called Lévy flights. In the presence of jumps, action landscapes with barriers can be efficiently explored, improving and even restoring ergodicity where traditional
diffusion approaches become inefficient. We explore different strategies for constructing efficient jump updates, which we deploy to address the
benchmark problem of topological freezing in 2d U(1) gauge theory.
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Materials Science
Insights into the Structural and Orientational Ordering of 2D Metal Halide Perovskites
Mustafa Mahmoud Aboulsaad, German Alvarez Carrero, Trupthi Devaiah Chonamada et al. (+4 more)
Metal halide perovskite nanoplatelets combine
quantum confinement with structural anisotropy, yet how thickness and processing govern their internal
crystal lattice versus collective organization remains unresolved. In this study, we separate internal structure, superlattice organization, and film texture using 2-5 monolayer CsPbBr3 nanoplatelets and larger nanocrystals across
spin-coating and drop-casting routes. Grazing incidence X-ray diffraction analysis of the specimens indicates that orthorhombic-compatible signatures recur throughout the thickness and deposition series, with a preserved
lattice-morphology relationship in which 020/040 and 101/202
lattice planes are associated with the platelet thickness and lateral dimensions, respectively. Upon deposition on the substrate, we notice a thickness-dependent crossover: 2-monolayer nanoplatelets remain predominantly face-on across deposition routes, whereas thicker nanoplatelets show marked processing sensitivity and orientational disorder. Processing therefore can be used as a tool to direct the NPL packing, establishing thickness as a key determinant of processing sensitivity.
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All authors Mustafa Mahmoud Aboulsaad, German Alvarez Carrero, Trupthi Devaiah Chonamada, Germán Salazar Alvarez, Ute Cappel, Rafael B. Araujo, Tomas Edvinsson
Mesoscale and Nanoscale Physics
Raman-detected quantum dot microscopy for nanoscale electrostatic potential imaging
Jiří Doležal, Amandeep Sagwal, Rodrigo Cezar de Campos Ferreira et al. (+1 more)
Quantification of electrostatic potentials at the nanoscale is crucial for understanding the principles governing properties of materials across multiple length scales. Currently, one of the most successful approaches relies on the charging response of a molecular
quantum dot, suspended on a tip of a scanning probe microscope and measured using dynamic force spectroscopy. We investigate the possibility of an optical detection, aiming to improve the speed and reduce the complexity of this measurement scheme. We show that the integrated tip-enhanced Raman scattering intensity strongly correlates with the charge state of the
quantum dot, and use it to map the electrostatic potential of a single atom. A quantitative equivalence with the established force spectroscopy method is found. We address the underlying photophysical principle of this new method by measuring the Raman spectra as a function of excitation wavelength and the molecular
quantum dot charge. We reveal that the observed Raman intensity variations are primarily driven by transitions between resonant and non-resonant Raman scattering regimes of the molecule.
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All authors Jiří Doležal, Amandeep Sagwal, Rodrigo Cezar de Campos Ferreira, Martin Švec
Strongly Correlated Electrons · Cross-listed from quant-ph
Captured weight and boundary leakage bound the error of sample-based spectral functions
Nicolás Bonilla Vargas
Rayleigh-Ritz on a subspace from sample-based
quantum diagonalization yields the spectral function of a probe state; we ask what bounds its error. The captured Born weight w does not do so alone: an analytic counterexample forces any bound indexed on it to its trivial value. On Hubbard rings at broadening $\eta=0.18t$, the probe's whole support (w=1) still has relative error 0.35–0.43: Rayleigh-Ritz displaces the poles a subspace keeps. The error is bounded instead by the missed weight and the
Hamiltonian coupling across the subspace boundary. Given the exact ground state, we prove for any orthogonal projector that the relative $L_1$ error lies between 1-w and $\min\{1+w,(1+\sqrt{w})(\sqrt{1-w}+\Lambda(\eta)/\eta)\}$, with $\Lambda$, that coupling at resolution $\eta$, computed from the Ritz pairs and the retained probe. We test it on L-site rings with classical Born draws of an exactly time-evolved probe, or their infinite-shot ranking; our device runs are execution records only. On the ranked subspaces the bound is vacuous at every operating fraction of the resource scan, at all five sizes up to a 10306296-determinant sector: its leakage branch exceeds the trivial bound 1+w by factors 1.66–8.61. It is informative only well above those fractions, where it is calibrated: at L=6–12 it first beats the trivial bound at a true error of (1.2–7.3)$\times10^{-3}$, though an unproven fit in 1-w is tighter on 11 of 14 splits. For the Born-ranked $A(k,\omega)$ at 85% of its sector, the bound is 350–900 times the true error. In the determinant basis, zero leakage at full weight needs every
symmetry-allowed determinant: the probe's measured Krylov support at L=6–14. Plane-wave orbitals reduce a momentum probe's support to one block, 1/L of an exponentially growing sector. At full weight a second-order certificate follows; below it, where every operating fraction lies, one is open.
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Mesoscale and Nanoscale Physics
Stability and optoelectronic properties of oligothiophene molecules confined in boron-nitride nanotubes : A many-body theoretical approach
Xavier Blase, Mauricio Rodriguez-Mayorga and Ivan Duchemin
We investigate the structural and optoelectronic properties of oligothiophene (nT) molecules encapsulated in boron-nitride (BN) nanotubes using density functional theory, many-body GW and Bethe-Salpeter equation approaches. We show that the binding energy is maximized for tube diameters of approximately 10 Å, decreasing gradually for larger diameters. The nT molecules can slide along the tube with a corrugation potential smaller than room temperature thermal energy, promoting their head-to-tail aggregation. Regarding the electronic properties, we find that hybridization with the tube electronic states has a much smaller effect than that of screening, which can close the nT photoemission gap by as much as an eV. A simple model for the polarization of the BN tube demonstrates how these polarization effects decrease with increasing nT molecule length and BN tube diameter. Compared to the gas phase optical properties, structural relaxation, hybridization, and screening can
redshift the absorption onset by up to 250 meV for isolated intercalated nTs. Additionally, the study of a head-to-tail sexithiophene dimer reveals an
exciton-
exciton interaction that splits the absorption onset into a lowest bright
exciton, separated by approximately 75 meV from a dark peak. This suggests possible collective effects upon the formation of nT chains inside BN tubes. Our results confirm and clarify experimental data, mitigating the conclusion that insulating BN tubes just act as a protecting environment for encapsulated molecules.
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Mesoscale and Nanoscale Physics
Field-controlled breaking and restoration of parity-time symmetry in Josephson interference
Yi-Chen Tsai, Yung-Yeh Chang, Tao-Yi Hsu et al. (+6 more)
Symmetry plays a fundamental role in determining the phases and physical properties of
quantum matter. Controlling
symmetry in mesoscopic superconducting devices provides a route to reconfigure their phase-coherent transport. Here we demonstrate
symmetry-selective Josephson interferometry in lateral NbTi/PtTe$_{\text{2}}$/NbTi junctions by controlling the relative orientations of the current and
magnetic field. From the supercurrent interference patterns, we construct a field-current
symmetry map that identifies configurations exhibiting or violating the device-level parity ($\mathcal{P}$), time-reversal ($\mathcal{T}$) and their combined $\mathcal{PT}$
symmetry. In the absence of an in-plane field, the junction exhibits a symmetric Fraunhofer pattern. An in-plane field parallel to the current produces a pronounced side-lobe asymmetry, whereas reversing both the current and the complete
magnetic-field configuration restores a generalized $\mathcal{T}$ relation. Remarkably, orienting the in-plane field perpendicular to the current restores the $\mathcal{PT}$-symmetric Fraunhofer response even at substantial field strengths. A microscopic model attributes this behavior to the interplay between disorder-induced potential variations and flux dipoles generated by in-plane-field Meissner focusing near the superconducting electrodes. Our results establish a reconfigurable Josephson interferometer in which the field-current geometry selects the
symmetry operation being probed and switches the device between
symmetry-broken and
symmetry-restored interference states.
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All authors Yi-Chen Tsai, Yung-Yeh Chang, Tao-Yi Hsu, Thomas Kuo, Chia-Nung Kuo, Chin-Shan Lue, Kuei-Lin Chiu, Chen-Hsuan Hsu, Chung-Ting Ke
Materials Science
Tuning electronic properties and Schottky contact in graphene-based van der Waals heterostructures by electric gating and interlayer coupling
Poonam Sharma, Archana Sharma and Alok Shukla
Van der Waals
heterostructures (vdW HTSs) incorporating
graphene (GE) have been an active area of research, both theoretical and experimental, due to their potential to yield devices with a wide variety of applications. In this paper, first-principles calculations are employed to investigate C$_{6}$N$_{6}$/GE, hg-C$_{3}$N$_{4}$/GE, and C$_{6}$N$_{6}$/hg-C$_{3}$N$_{4}$ 2D vdW HTSs. A systematic analysis of structural and thermodynamic stability, electronic, mechanical, and optical properties of
semiconductor/metal and
semiconductor/
semiconductor interfaces is performed. Both
semiconductor/metal HTSs form $n$-type Schottky contacts, which can be converted into $p$-type Schottky or Ohmic contacts by tuning the external perpendicular electric field and the interlayer coupling. In the
semiconductor/
semiconductor C$_{6}$N$_{6}$/hg-C$_{3}$N$_{4}$ HTS, the valence and conduction band edges originate from distinct layers, resulting in a type-II band
alignment that promotes efficient electron-hole (e-h) separation. Furthermore, the band
alignment can be effectively tuned between type-I and type-II by applying an external electric field and varying the interlayer distance. From the optical absorption spectra of the HTSs, we concluded that the C$_{6}$N$_{6}$/GE and hg-C$_{3}$N$_{4}$/GE exhibit an optical response across a wide frequency range, whereas the C$_{6}$N$_{6}$/hg-C$_{3}$N$_{4}$ HTS shows prominent activity primarily in the ultraviolet region. Using the $G_{0}W_{0}$+BSE approach, the
exciton binding energies are also calculated for the gapped systems, namely C$_{6}$N$_{6}$, hg-C$_{3}$N$_{4}$ monolayers, and their HTS (C$_{6}$N$_{6}$/hg-C$_{3}$N$_{4}$), yielding values of 1.01 eV, 1.14 eV, and 1.18 eV, respectively, highlighting strong e-h interactions. Moreover, the band-edge analysis of C$_{6}$N$_{6}$/hg-C$_{3}$N$_{4}$ HTS further favors pronounced interlayer e-h coupling.
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Materials Science · Cross-listed from physics.plasm-ph
Assessing the Projector Augmented-Wave Method for Stopping Power Calculations
Bryn Lloyd, Dirk O. Gericke, Gilles Rodway-Gant et al. (+1 more)
The stopping power of charged particles is investigated using time-dependent density functional theory (TDDFT). Such simulations are made possible by recent advances in computational resources and numerical implementations of this first-principles method. In practice, DFT simulations widely employ the projector augmented-wave (PAW) method to approximate all-electron behaviour, but the implications of the PAW approximation for non-adiabatic stopping simulations remain insufficiently explored. Here, the suitability of the PAW method for stopping power simulations is evaluated. A workflow for generating and selecting PAW
datasets tailored to these simulations is developed, enabling systematic optimisation of augmentation radii and projector constructions. The approach is applied to
proton stopping in FCC aluminium, demonstrating how
dataset design influences stopping predictions, and enabling an investigation of
crystal channelling effects on charged-particle transport.
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All authors Bryn Lloyd, Dirk O. Gericke, Gilles Rodway-Gant, Gianluca Gregori
Mesoscale and Nanoscale Physics
A magnonic-optoelectronic reservoir for physical reservoir computing
Alexey B. Ustinov, Ivan Y. Tatsenko, Andrei A. Nikitin et al. (+1 more)
Physical reservoir computing is a promising approach for fast and energy efficient computer
vision, natural
language processing, and general pattern recognition. This work presents a physical reservoir based on magnonic-optoelectronic oscillator (MOEO). This approach allowed us to realize short-term
memory and nonlinearity as separate system components. The device`s optical path uses a fiber-optic delay line as a short-term-
memory element. The microwave path is responsible for nonlinear mapping of input data to a higher-dimensional space. The strong four-wave nonlinearity of
spin waves propagating in an yttrium-iron garnet (YIG) ferrite film enables the process. The reservoir performance is evaluated by completing task-independent tests known as short-term
memory (STM) and parity-check (PC) tasks. In addition, a numerical model of the MOEO based reservoir is developed. Results of the numerical simulation of the reservoir performance are in good agreement with the experimental data.
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All authors Alexey B. Ustinov, Ivan Y. Tatsenko, Andrei A. Nikitin, Mikhail P. Kostylev
Mesoscale and Nanoscale Physics
Tunable Fano Resonance and Frequency Locking in a Graphene-SiNx Hybrid Nanomechanical Resonator
Ateesh K. Rathi, Javed A. Mondal, Rajan Singh et al. (+3 more)
Fano resonances, arising from the interference between discrete and continuum states, are observed across a wide range of
quantum and classical systems. Here, we report the experimental observation of Fano resonances in a
graphene SiNx hybrid nanomechanical system modeled as coupled oscillators. The broad, low quality factor
graphene mode plays the role of the continuum, while the dense comb of sharp, high quality factor SiNx modes provides the discrete states. The inter-mode detuning is tunable via a DC gate voltage, enabling dynamic control of the Fano resonance: we demonstrate gate controlled switching of both the sign and the magnitude of the Fano asymmetry parameter $q$, in quantitative agreement with a coupled oscillator theory that predicts $q=-\cot\phi$, with $\phi$ the phase of the continuum response. At strong drive, the
graphene mode enters the Duffing regime and its jump-down frequency locks to successive SiNx modes, producing a staircase of drive insensitive frequency plateaus; a weak seeding tone deterministically switches the resonator between adjacent locked states. The dense SiNx mode thus acts, in the linear regime, as the discrete states of a tunable Fano interferometer and, in the nonlinear regime, as a frequency ruler that stabilizes and quantizes the
graphene oscillation. This platform offers a controllable mechanical realization of Fano interference and opens new avenues for high resolution hybrid resonant sensors and stable nanomechanical frequency references.
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All authors Ateesh K. Rathi, Javed A. Mondal, Rajan Singh, Ryan J.T. Nicholl, Kirill I. Bolotin, Saikat Ghosh
Materials Science
Javier Sivianes, Enrique Boquete-Someso, Daniel Hernangómez-Pérez et al. (+1 more)
The optical response of
magnetic materials is conventionally classified through
magnetic space groups (MSGs), where
spin and
lattice are locked by the relativistic
spin-orbit interaction. However, most optical observables are governed primarily by nonrelativistic physics, and thus a purely MSG-based description can overlook important insights. Here we systematically show that
spin-space groups (SSGs), which operate at the nonrelativistic level, provide a broader and more predictive framework for analyzing a variety of optical responses of magnets. Focusing on linear optical absorption, we derive the transformation rules imposed by SSGs and show that they generate effective real-space point groups, which can enforce relations among charge response coefficients that are absent from conventional MSG analysis. We illustrate the basic principle in a Lieb-
lattice altermagnet model with tunable
spin-orbit coupling, where SSG predictions on the linear dichroism remain remarkably accurate even when relativistic band splittings become sizable. We further establish the predictive power of this framework through first-principles calculations on two altermagnetic candidates: the actinide UCr2Si2C, where the optical absorption remains nearly isotropic despite its strong
spin-orbit coupling and the pronounced anisotropy apparent from
magnetic symmetries, and the transition-metal fluoride RbMnF4, where birefringence is confined to a single plane by
symmetries emerging exclusively from SSGs. Finally, we extend the concept to the
spin Hall response of the coplanar noncollinear antiferromagnet ScMnO3, where SSGs explain the hierarchy of calculated
spin Hall coefficients, demonstrating their direct relevance to spintronics as well.
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All authors Javier Sivianes, Enrique Boquete-Someso, Daniel Hernangómez-Pérez, Julen Ibañez-Azpiroz
Materials Science · Cross-listed from physics.chem-ph
Extracting a nitrile-centered, ether-assisted motif hierarchy for lithium-battery electrolyte design from billion-scale molecular space
Yifeng Xia, Guanghui Wang, Sining Wang et al. (+4 more)
Designing electrolyte molecules for lithium batteries requires balancing electronic stability with appropriate Li+ solvation, yet the structural basis remains unclear across chemically diverse molecules. High-throughput screening expands the searchable space, but ranked candidates alone do not reveal recurring motifs or their applicability limits. We searched nearly one billion GDB13 structures using electronic–solvation descriptors without explicit functional-group preferences or scaffold constraints. Across descriptor weights, high-ranking populations separated into a nitrile-dominant regime and a coexistence regime containing substantial fractions of both nitrile- and ether-containing molecules. These regimes together define a nitrile-centered, ether-assisted motif hierarchy: nitrile remains favored across broad weight ranges, whereas ether becomes prominent under stronger electrostatic and polarity constraints. Encoding this hierarchy in a generative model expands the candidate space beyond GDB13 and yields high-scoring fluorinated structures without an explicit fluorination reward. Explicit-solvent molecular dynamics simulations show weak, exchangeable coordination of representative candidates without displacing ethylene carbonate from the dominant first solvation shell around Li+; effects on ion association and transport depend on molecular structure and concentration. These results establish a quantitative, interpretable and physically bounded motif hierarchy that systematizes established nitrile and ether chemistry for lithium-battery electrolyte design.
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All authors Yifeng Xia, Guanghui Wang, Sining Wang, Wenting Chen, Zheng Cheng, Jinzhe Zeng, Qiangqiang Gu
Superconductivity
Koki Shimura, Shuntaro Sumita and Yusuke Kato
We study the dynamical
spin response of UTe$_2$ by using a mixed-dimensional periodic Anderson model. Within the BCS-RPA formalism, we examine how the $f$-orbital character of the quasiparticles affects
magnetic excitations in both the normal and superconducting (SC) states. In the normal state, finite mixing between localized $f$ electrons and conduction electrons produces a hybridization gap and enhances the
spin response at $\mathbf{Q}_{\mathrm{Y}} = (0,\pi,0)$, indicating that the
magnetic excitation originates from particle–hole scattering across the hybridization gap. In the SC state, we compare four odd-parity irreducible representations, $A_u$, $B_{1u}$, $B_{2u}$, and $B_{3u}$, for the
spin-triplet order parameter. We find that, for the component of the
spin susceptibility parallel to the $\mathbf{d}$ vector, a pronounced superconductivity-induced
spin resonance appears at $\mathbf{Q}_{\mathrm{Y}}$ only in the $B_{2u}$ state. This behavior arises because the $B_{2u}$ order parameter remains finite and changes its sign between the relevant $f$-electron-dominated
Fermi-surface regions connected by $\mathbf{Q}_\mathrm{Y}$ near $k_z=\pi$. The sign-change criterion is applicable to multiband
superconductors in three-dimensional heavy-
fermion systems, in the presence of (i) low-dimensional portions of the
Fermi surface connected by a nesting vector, (ii) the dominance of the $f$-electron character, and (iii) the finite amplitude of SC gap on the portions.
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Materials Science
Effect of Magnetic Vacancies on the Spontaneous Spin-Reorientation Transition in HoFe$_{1-x}$Al$_x$O$_3$ Single Crystals
S. A. Skorobogatov, V. A. Babkina, M. S. Pavlovskii et al. (+5 more)
In this work, we report the first growth of single
crystals of the substitution series HoFe$_{1-x}$Al$_x$O$_3$ with aluminium concentrations up to $x=0.2$ and investigate the
evolution of their spontaneous
spin-reorientation transition (SRT). Among rare-earth orthoferrites, HoFeO$_3$ exhibits a distinctive sequence of
magnetic phases ($\Gamma_4$-$\Gamma_{24}$-$\Gamma_{12}$-$\Gamma_2$). This complex sequence arises from the competition between the $K_{ac}$ and $K_{ab}$ anisotropies associated with the Ho$^{3+}$ ions and the effective
magnetic field produced by the weak
ferromagnetic moment of the canted Fe$^{3+}$ sublattice. Introducing
magnetic vacancies perturbs the
antiferromagnetic compensation of the Fe$^{3+}$ subsystem in the $ab$ plane and generates an additional effective
magnetic field acting on the Ho$^{3+}$ ions. This field alters the balance between the $K_{ac}$ and $K_{ab}$ anisotropies within the SRT temperature range and thereby broadens the stability range of the $\Gamma_{12}$ phase in the
magnetic phase diagram.
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All authors S. A. Skorobogatov, V. A. Babkina, M. S. Pavlovskii, M. I. Kolkov, S. V. Semenov, I. N. Khoroshiy, S. E. Nikitin, K. A. Shaykhutdinov
Soft Condensed Matter
Direct inference of viscoelastic memory from chirp rheometry via physics-informed Gaussian processes
Isaac Y. Miranda-Valdez, Juha Koivisto and Mikko J. Alava
Soft materials remember their deformation history, and identifying that
memory from experiments is essential for predicting how these materials behave under real-world loading conditions. Chirp rheometry has recently emerged as a way to accelerate this characterization, compressing hours of conventional measurement into seconds and yielding thousands of stress-strain pairs per experiment. That density is then largely discarded: the standard pipeline reduces the record to a handful of frequency-domain estimates before any constitutive model is fitted. We introduce a physics-informed Gaussian process framework that infers the material's constitutive law directly from the raw time-domain record of a single chirp, selecting among candidate
memory kernels and parametrizing the selected one without any intermediate signal processing step. Because the framework infers the
memory kernel rather than the specific waveform used during training, it predicts the response to deformation histories it never saw, without retraining. The method also resolves material
evolution within a single chirp directly in the time domain.
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Materials Science
Dimensionality Mismatch Enables Decoupled Heat and Charge Transport
Luman Shang, Shuming Zeng, Chenhan Liu et al. (+1 more)
Decoupling heat and charge transport is a key challenge in thermoelectrics. Here, we identify a route to spatially separate
phonon and carrier transport in quasi-one-dimensional materials through high-throughput screening of the Materials Project database. Representative Sn$_2$S$_3$ and SbTeI exhibit a strong-intrachain–weak-interchain bonding hierarchy that favors
phonon propagation along the chains while suppressing transverse
lattice heat transport. In contrast, transverse valence-band states provide effective interchain electronic coupling and relatively light hole transport. This mismatch between
lattice and electronic transport dimensionalities produces an inverted thermal–electrical anisotropy. Across the screened candidates, interchain
lattice thermal conductivity is strongly suppressed, whereas hole transport remains weakly anisotropic or even favors the interchain direction. For SbTeI, this decoupling yields a maximum $zT$ of approximately 2.1 near 900~K. These results establish dimensionality mismatch as a general strategy for decoupling
phonon and carrier transport in thermoelectric materials.
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All authors Luman Shang, Shuming Zeng, Chenhan Liu, Yu Wu
Materials Science
Bond Disproportionation, Ligand Holes, and Persistent Spin Textures in Ag$_2$BiO$_3$
Atanu Paul, Subhadeep Bandyopadhay, Anupam Mondal et al. (+1 more)
The origin of the proposed bond disproportionated insulating state of the non-centrosymmetric ($Pnn2$) phase of Ag$_{2}$BiO$_{3}$ is explored using first principles electronic structure calculations. The novel insulating state is elucidated by first considering the initially proposed centosymmetric metallic ($Pnna$) phase of Ag$_{2}$BiO$_{3}$. Our calculations reveal that the valence skipping Bi$^{4+}$ ions in this phase are better described as Bi$^{3+}\underline{L}$ with completely filled Bi-(6$s$) states and a ligand hole. However,
phonon calculations indicate that the metallic ($Pnna$) state is dynamically unstable. Structural stability is achieved through breathing distortions of the oxygen octahedra, resulting in two inequivalent Bi sites and a reduction of
symmetry to the $Pnn2$ phase. Electronic structure calculations further reveal that the $Pnn2$ phase is a bond disproportionated
insulator where the nominal charge state of Bi is described by : 2[Bi$^{3+}\underline{L}$ (Bi$^{4+}$)] $\rightarrow$ Bi$^{3+}\underline{L}^{2-\delta}$ (Bi1$^{5+}$) + Bi$^{3+}\underline{L}^{\delta}$ (Bi2$^{3+}$), highlighting the crucial role of ligand holes in driving the insulating state. Next we have investigated the electronic structure of Ag$_{2}$BiO$_{3}$ in the insulating ($Pnn2$) phase including
spin-orbit coupling. Our density functional theory (DFT ) calculations complemented by ${\bf k.p}$ model
Hamiltonian analysis reveal persistent
spin-textures around the $X$ and $Y$ high
symmetry points of the orthorhombic Brillouin zone imposed by non-symmorphic
symmetry, positioning Ag$_{2}$BiO$_{3}$ as a promising candidate for spintronic applications.
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All authors Atanu Paul, Subhadeep Bandyopadhay, Anupam Mondal, Indra Dasgupta
Materials Science
Toward the Ultimate Limit: Elemental Metals in One Dimension
Mohammad Bagheri, Kameyab Raza Abidi, Sushree Sarita Sahoo et al. (+2 more)
Low-dimensional materials exhibit extraordinary properties that make them promising candidates for advanced technologies. Although they have been investigated extensively, most of the research has focused on layered two-dimensional (2D) materials. Here, inspired by recent advances in atomically thin metallenes, we further reduce dimensionality and use density-functional theory simulations to study the geometry, energetics, elasticity, and electronic structure of 40 non-
magnetic one-dimensional (1D) atomic chains of elemental metals. We find that nearly all chains have a buckled ground state, nine chains are distorted, and three chains—Cd, Hg, and Sr—are semiconducting with an electronic gap. We also find that transition metals retain a substantial fraction of their 3D bulk cohesive energy even in 1D chains. We assessed chains' dynamical stabilities by molecular dynamics simulations and found that 26 of them are thermodynamically stable at 100 K. Finally, we performed chain pulling simulations to investigate the straightening dynamics of selected stable chains. Given that experimental techniques have recently reached the 1D-chain limit, our systematic study provides a foundation and timely guide to accelerating synthesis and characterization of these materials.
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All authors Mohammad Bagheri, Kameyab Raza Abidi, Sushree Sarita Sahoo, Sukhbir Singh, Pekka Koskinen
Materials Science
Efficient nonequilibrium electron dynamics from first-principles: leveraging Koopmans spectral functionals and Wannier localization
Giovanni Cistaro, Miguel Sá, Davide Sangalli et al. (+2 more)
We present an efficient first-principles approach for simulating the nonequilibrium electron dynamics in extended systems beyond the linear regime. The method combines Koopmans-compliant functionals, which provide an accurate quasiparticle band structures, with the real-time
evolution of the electronic density
matrix in a Wannier basis within the Hartree plus screened exchange (HSEX) approximation. The locality of the orbital basis enables physically motivated approximations that significantly reduce both the computational cost and
memory requirements while preserving accuracy. The screened Coulomb interaction, the central ingredient of the HSEX self-energy, is computed efficiently using density-functional perturbation theory. We
benchmark the approach in the linear regime against experimental spectra and reference Green's function calculations for systems featuring both weakly and strongly bound
excitons. Moving to the nonlinear regime, we investigate high-harmonic generation (HHG) in silicon and lithium fluoride. While in silicon the HHG spectrum is largely governed by the quasiparticle band structure, in LiF, a material featuring strong excitonics effect, the harmonic emission is selectively enhanced at excitonic resonances, suggesting that HHG probes correlated electron-hole excitations rather than solely the quasiparticle band structure. The present framework enables fully ab-initio simulations of excitonic effects in nonlinear optical spectra at a significantly reduced computational cost compared to real-time Green's function approaches, providing an efficient route to the study of ultrafast and strong-field phenomena in solids.
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All authors Giovanni Cistaro, Miguel Sá, Davide Sangalli, Antonio Picón, Nicola Colonna
Strongly Correlated Electrons
Non-Equilibrium Instantaneous Approximation and Dipole Forbidden d-d Transitions
Marco Marino, Lasse Sternemann, Mirko Cinchetti et al. (+1 more)
Time- and angle-resolved photoemission spectroscopy provides direct access to pump-induced changes in the electronic structure of correlated materials, but its theoretical description generally requires computationally demanding two-time non-
equilibrium calculations. We introduce an instantaneous approximation for pump-driven correlated systems, based on a separation between the rapid decay of the Green's functions in the relative time variable and their slower
evolution in the average time. Combined with a one-shot dynamical mean-field construction at the Hubbard I level, the method incorporates the driven dynamics of the local correlated shell into the
lattice Green's function while retaining momentum resolution. We also derive an effective coupling for nominally dipole-forbidden d-d excitations. It arises from a dipole-allowed d-p transition followed by p-d hybridization; beyond the instantaneous limit, the same process produces an energy-dependent vertex correction to the optical response. As a proof of principle, we apply the framework to paramagnetic and
antiferromagnetic FePS3, using a density-functional theory derived tight-binding model together with a supercell unfolding procedure. The calculated momentum-resolved spectra reproduce the main qualitative features observed after excitation of the first and second d-d transitions in recent time-resolved photoemission experiments.
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All authors Marco Marino, Lasse Sternemann, Mirko Cinchetti, Frithjof B. Anders
Superconductivity · Cross-listed from quant-ph
Controlling rotations of magnetically levitated superconductors
Fynn Köller, Dominik Maile, Joachim Ankerhold et al. (+3 more)
Magnetically trapped type-I
superconductors are promising candidates for precision experiments at the
quantum-to-classical borderline, with applications in
quantum sensing of forces and accelerations and fundamental tests of
quantum physics. Here, we show how the rotational motion of micron-sized
superconductors is strongly affected by (i) the diamagnetic torques due to the gradient of the trapping field and by (ii) the gyromagnetic coupling due to Einstein-de Haas and Barnett effects. We show that this allows the three-dimensional
alignment of asperhical
superconductors in the trap center, as required for future sensing applications and
quantum experiments, and determine the resulting librational trapping frequencies. Finally, we propose an experiment to probe gyromagnetic coupling in levitated
superconductors and we discuss how it can be used to control the particle rotation.
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All authors Fynn Köller, Dominik Maile, Joachim Ankerhold, Klaus Hornberger, Witlef Wieczorek, Benjamin A. Stickler
Other Condensed Matter · Cross-listed from quant-ph
Half a qubit: an algebraic fractionalization
Po-Yao Chang
Fractionalizing a
quantum two-level system is usually associated with encodings based on pairs of Majorana
fermions—an operational fractionalization. We show an alternative algebraic fractionalization by
embedding Székely's classical “half-coin” into a non-Hermitian Krein space. The coefficients of $(q+pz)^{1/2}$ define a signed sequence and a normalized, non-Hermitian biorthogonal operator describing a biorthogonal half-
qubit. We prove that two such objects fuse into an arbitrary pure
qubit through the signed Vandermonde convolution that the collective $N\ge2$ vectors are null in Krein space. $L_1$ norm of the half-
qubit follows in closed form, $\lVert p\rVert_1 = 2\sqrt{q}-\sqrt{q-p}$. Its $L_1$ norm increases monotonically with the bias and attains its supremum $\sqrt{2}$ precisely at the unbiased point $p=q=1/2$. Interestingly, we identify two structural results as follows. First, number parity and the $\eta$-metric generate a distinguished commuting $\mathbb Z_2\times\mathbb Z_2$ subgroup. Second, we find the $\eta$-metric obstructs any local $\eta$-self-adjoint partner of the parity, so a half-
qubit carries a $\mathbb{Z}_2$ observable but no local $SU(2)$. The full Pauli
algebra emerges only upon fusion. We then show that the construction survives truncation of the Fock basis: the fused
qubit is exact at every cutoff, and the Vandermonde cancellation is visible in sign-weighted
photon-number statistics, and can be tested using existing cavity and trapped-ion state-synthesis methods. Finally, we generalize this algebraic fractionalization to a $1/n$-
qubit, which can be achieved by replacing the square root with an $n$th root.
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