Statistical Mechanics
Temporal reversibility of a fluid mixture under concentration gradient
O. Politano, Alejandro L. Garcia, F. Baras et al. (+1 more)
A binary fluid mixture in contact with lateral particle reservoirs is considered. By imposing different particle concentrations in these reservoirs, the system can be maintained under controlled non-
equilibrium conditions. Previous
stochastic approaches have revealed an unexpected property of the system's state trajectory, namely that it remains time-reversible even when the system is driven out of
equilibrium. In the absence of relevant experimental evidence, we employ microscopic molecular dynamics simulations to assess the validity of this surprising result. Remarkably, the simulation results unambiguously confirm the prediction of the
stochastic analysis.
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All authors O. Politano, Alejandro L. Garcia, F. Baras, M. Malek Mansour
Mesoscale and Nanoscale Physics
Electrically tunable orbital coupling and quantum light emission from O-band quantum dot molecules
P.S. Avdienko, L. Hanschke, Q. Buchinger et al. (+10 more)
We present the observation of electrically tunable
quantum coupling of orbital states in individual InAs/InGaAs
quantum dot molecules emitting in the telecom O-band (~1300 nm). By tuning the static electric field along the growth axis of the QD-molecule, we observe pronounced anticrossings between excitonic transitions and determine the dependence of the interdot electron tunnel coupling on the interdot separation. As the electric field applied along the growth axis of the QD-molecules increases, positively charged
exciton complexes sequentially emerge in the time-integrated emission spectra due to electron escape from the system while holes remain trapped. Moreover, for strong pumping, biexciton emission from the O-band molecules is identified. We demonstrate single-
photon emission from the InAs/InGaAs QD-molecule emitting around 1300 nm with a g(2)(0) = 0.017(2) and explore the impact of tuning orbital coupling on the second-order correlation function.
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All authors P.S. Avdienko, L. Hanschke, Q. Buchinger, N. Akhlaq, I. Lubianskii, E. Weber, H. Riedl, M. Kamp, T. Huber-Loyola, S. Hoefling, A. Pfenning, K. Mueller, J.J. Finley
Materials Science
First principles electric field gradients at A and B site cations across the NaRTiO4 Ruddlesden Popper series
L. F. Almeida, A. N. Cesário, P. A. Sousa et al. (+5 more)
The $n = 1$ Ruddlesden-Popper titanates, NaRTiO$_{4}$ (R = rare-earth), exhibit a structural behaviour where non-centrosymmetry is driven by cooperative oxygen octahedral rotations (OORs) rather than conventional second-order Jahn-Teller distortions. In this work, we present an ab-initio investigation of the structural, electronic and hyperfine properties of the entire NaRTiO$_{4}$ series across the two disputed ground states, $Pbcm$ and $P\bar{4}2_1m$, and the high temperature $P4/nmm$
symmetries. Our results reveal an ionic-radius-dependent
evolution from a tilt-dominated regime for small rare-earth ions to a distortion-dominated regime for larger cations, leading to an asymptotic regime in which the high-temperature phase becomes increasingly competitive with the ground-state structures as the ionic radius increases. In parallel, the electronic band gap follows a systematic
evolution across the series, reflecting the underlying structural changes and the increasing dominance of octahedral distortions at larger ionic radii. The Electric Field Gradient (EFG) tensor reveals that, in the large-radius limit, all
symmetries tend locally towards a similar environment. Away from this limit, the EFG tensor for different
symmetries progressively diverges, providing a sensitive probe for phase transitions and revealing
symmetry-specific fingerprints, particularly for the rare-earth and Ti sites. By establishing these EFG signatures, this work provides a roadmap for experimental techniques, such as
Nuclear Magnetic Resonance (NMR) and Perturbed Angular Correlation (PAC), to resolve the ground-state
symmetry of these structures.
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All authors L. F. Almeida, A. N. Cesário, P. A. Sousa, P. Rocha-Rodrigues, L. V. C. Assali, H. M. Petrilli, J. P. Araújo, A. M. L. Lopes
Materials Science · Cross-listed from physics.plasm-ph
Permeation behaviour of hydrogen isotopes in molten FLiBe (2LiF-BeF2): Identifying sources of uncertainty and associated measurement challenges
Abhishek Saraswat, Weiyue Zhou, Nayoung Kim et al. (+7 more)
This paper presents results from systematic investigations conducted in the HYPERION facility to quantify permeabilities of hydrogen isotopes in FLiBe over a temperature range of 773K - 973K. To address the knowledge gap resulting from widely scattered transport parameters reported in the earlier studies, HYPERION experiments incorporate specific provisions to probe unsubstantiated assumptions, including a one-dimensional permeation, membrane surface coverage by the salt, and ideal wettability of the salt-metal interface. Suppression of the isotopic transport behaviour for metal-side charging highlights the permeation barrier characteristics of a bubble-laden Ni-FLiBe interface, impacting permeability by up to 77%. This work attempts to resolve this issue via salt-side charging and informs constraints on the permeant charging methodology for future studies. The initial insights from HYPERION experiments call into question the design choices and estimated transport properties in earlier works. This study provides a plausible explanation for the observed scatter in H/D/T transport in FLiBe.
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All authors Abhishek Saraswat, Weiyue Zhou, Nayoung Kim, Jaron F. Cota, Guiqiu Zheng, Alexander A. Khechfe, Caroline S. Barthel, Michael P. Short, Rémi Delaporte-Mathurin, Kevin B. Woller
Mesoscale and Nanoscale Physics
Probing Azimuthal Anatomy of Hyperbolic Whispering Gallery Modes in hBN
Bogdan Borodin, Samyobrata Mukherjee, Shivaksh Rawat et al. (+8 more)
Scattering-type scanning near-field optical microscopy (s-SNOM) is a powerful tool for investigating polaritonic modes. However, an inherent limitation of this technique is that excitation and detection occur at the same location. This constraint makes it challenging to resolve excitations with complex spatial structures, which can exhibit delicate dependence on the in-coupling conditions. Here, we present a strategy to overcome this limitation by introducing an auxiliary cavity, which serves as a stationary near-field excitation source. This configuration introduces a tip-independent and spatially separated excitation source, allowing the s-SNOM tip to primarily probe the resulting modal field distribution with minimal perturbation of the resonator. We apply this approach to whispering gallery modes (WGMs) of
hyperbolic phonon-polaritons in hexagonal boron nitride resonators. Through spatially resolved near-field maps, we directly observe subwavelength polaritonic WGMs with large and discrete azimuthal momentum ($k_\phi / k_0$ up to 15). Direct access to the modal field distributions enables identification of the azimuthal mode numbers and their frequency-dependent excitation spectra. We further show that, over finite spectral intervals, the modes continuously adjust their effective refractive index while preserving a fixed azimuthal mode number before transitioning to the next resonant state. Numerical simulations support the experimental observations and confirm the observation of
hyperbolic WGMs. This approach enables direct visualization of previously hidden mode structures in
hyperbolic cavities and opens new opportunities for studying and engineering confined polaritonic states.
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All authors Bogdan Borodin, Samyobrata Mukherjee, Shivaksh Rawat, Seojoo Lee, Thomas Poirier, Kenji Watanabe, Takashi Taniguchi, James H. Edgar, Hanan Herzig Sheinfux, Gennady Shvets, Petr Stepanov
Mesoscale and Nanoscale Physics
A Unified Multiscale Auxiliary PINN Framework for Generalized Phonon Transport
Roberto Riganti and Luca Dal Negro
Nanoscale thermal transport is governed by the
phonon Boltzmann transport equation (BTE). However, simulating the sub-continuum dynamics remains computationally prohibitive due to the high dimensionality of the phase space and the intrinsic nonlinearity of the scattering collision operator. Traditional numerical solvers and standard physics-informed neural networks (PINNs) inherently struggle with these integro-differential equations due to deterministic quadrature limitations, artificial thermalization introduced by the relaxation time approximation (RTA), and multiscale spectral bias. This work introduces a multiscale auxiliary physics-informed neural network (MTNet) to solve the generalized equation of
phonon radiative transfer (GEPRT). By leveraging an auxiliary formulation, this mesh-free framework recasts the GEPRT into a fully differential system, enabling the analytical evaluation of scattering operators via automatic differentiation and facilitating scalable multi-GPU parallelization. To circumvent optimization stiffness, the architecture employs a decoupled, shallow neural network explicitly constrained by radiative
equilibrium. MTNet is validated by simulating steady-state cross-plane transport in a silicon thin film, successfully capturing ballistic-diffusive regimes and characteristic boundary slips across extreme temperature gradients ($\Delta T = 100$ K) beyond the standard linearization approach. Furthermore, we show that our framework successfully solves a
geometric inverse problem in a slab geometry, retrieving the unknown slab thickness based only on interface temperature constraints in the mesoscopic regime. Ultimately, MTNet establishes a robust, fully differentiable foundation for predicting high-fidelity kinetic transport and extracting material properties in next-generation nanostructures.
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Materials Science · Cross-listed from astro-ph.EP
Hydrogen-helium immiscibility boundary in gas-giant planetary interiors from machine-learning molecular dynamics
Xiaoyu Wang, Sebastien Hamel and Bingqing Cheng
The location of the hydrogen-helium (H/He) immiscibility boundary controls whether and where helium rain occurs in
giant planets, yet it remains uncertain because high-pressure experiments are challenging and ab initio simulations are limited in system size and simulation time. We map this boundary by computing composition-dependent chemical potentials from large-scale molecular dynamics driven by machine learning potentials trained on three density functional approximations (PBE, vdW-DF, and the hybrid HSE). Across the pressure range of 100-1000 GPa, the demixing temperatures are typically ~2000 K lower than previous ab initio simulations using small system sizes, and this discrepancy is larger than the estimated error from the chosen density functionals, machine learning potentials, neglect of
nuclear quantum effects, and statistical uncertainties. Fitting the H/He mixing free energy to a Redlich-Kister regular solution model rationalizes the thermodynamic driving force for phase separation and provides a predictive representation of the boundary. Comparing with current planetary interior profiles indicates that helium rain is plausible in Saturn but unlikely in the warmer interior of Jupiter. Our results narrow the uncertainty in the H/He immiscibility boundary and provide inputs for planetary models that couple demixing, heat transport, and composition gradients in gas
giants.
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Superconductivity
Disorder-Driven Enhancement of Coulomb Repulsion Governs The Superconducting Dome in Ionic-Liquid-Gated Quasi-2D Materials
Giovanni Marini, Pierluigi Cudazzo and Matteo Calandra
The superconducting dome in the Tc versus doping phase diagram, found in cuprates, nickelates, twisted
bilayer graphene, and transition metal dichalcogenides, is often considered a signature of unconventional pairing. Identifying the underlying mechanisms of any of these phase diagrams and developing a reliable theoretical understanding of it remains a critical challenge. Here we demonstrate that, in ionic-
liquid-gated quasi-2D materials, the disordered ionic potential from the frozen ionic
liquid drives the system close to Anderson transition. In this regime, quenched charge fluctuations and reduced screening markedly enhance repulsive Coulomb interactions, suppressing Tc and naturally leading to the formation of a superconducting dome. By integrating a many-body approach including disorder with first-principles calculations, we obtain the phase diagrams and tunneling spectra of gated few-layers transition metal dichalchogenides in robust quantitative agreement with experiments. Our findings establish that disorder-driven enhancement of Coulomb repulsion is a fundamental feature of ionic-
liquid-gated quasi-2D materials at high bias.
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Soft Condensed Matter
A non-local constitutive model for the Mullins effect in filled elastomers
Keven Alkhoury
Filled rubber-like materials are widely used in engineering applications and are well known to exhibit the Mullins effect. In this work, an established local constitutive model from the literature is extended to a non-local setting to resolve the mesh dependence inherent to the local approach. Non-local effects are incorporated using two separate approaches: (i) a Helmholtz-type equation governing a non-local soft volume fraction, and (ii) a
Laplacian term introduced directly into the soft volume fraction local
evolution law. In both formulations, an additional governing partial differential equation arises and is solved numerically in Abaqus using an analogy with the heat equation. The two approaches yield different results, leaving the choice between them to be guided by experimental findings. The details of the implementation, along with the code developed in this work are also provided.
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Strongly Correlated Electrons
Effect of spin-orbit coupling on spin and orbital ordering in Sr$_{n+1}$Cr$_n$O$_{3n+1}$, $n=1,2$
Cristian Fanjul and A. A. Aligia
We incorporate
spin-orbit coupling (SOC) into effective Kugel-Khomskii models for the $n=1$ and $n=2$ members of the Ruddlesden-Popper series Sr$_{n+1}$Cr$_n$O$_{3n+1}$. These model contain interacting
spins 1 and pseudospins 1/2 at each site describing
spin and orbitals degrees of freedom respectively. We solve the models at zero temperature using pseudospin bond operators and
spin waves. We find that for realistic parameters, SOC dominates the physics of the compound Sr$_{2}$CrO$_{4}$ with almost decoupled single CrO$_2$ planes. The
spin ordering is
antiferromagnetic, with nearest-neighbor Cr
spins aligned antiparallel. The corresponding orbital configuration is $d_{xy \uparrow }^{1}(d_{xz\uparrow }^{1}-id_{yz\uparrow }^{1})$ or $d_{xy \downarrow }^{1}(d_{xz\downarrow }^{1}+id_{yz\downarrow }^{1})$ depending on the
spin of the site. In contrast, for the
bilayer compound Sr$_{3}$Cr$_{2}$O$_{7}$ we find that the effect of the SOC is weak and the system prefers to form pseudospin singlets in the $z$ direction perpendicular to the planes. The
spin order is
antiferromagnetic within each plane and
ferromagnetic between planes, in agreement with previous studies.
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Statistical Mechanics · Cross-listed from quant-ph
Process-tensor approach to full counting statistics of charge transport in quantum many-body circuits
Hari Kumar Yadalam and Mark T. Mitchison
We introduce a numerical tensor-network method to compute the statistics of the charge transferred across an interface partitioning an interacting one-dimensional many-body
lattice system with $U(1)$
symmetry. Our approach is based on a
matrix-product state representation of the process tensor (also known as influence functional or influence
matrix) describing the effect of the bulk system on the degrees of freedom at the interface, allowing us to evaluate a multi-time correlation function that yields the moment-generating function of charge transfer. We develop a scheme to truncate non-Markovian correlations which preserves the proper normalization of the process tensor and ensures the correct physical properties of the generating function. We
benchmark our approach by simulating magnetization transport within the Heisenberg
spin-$1/2$ XXZ brickwork
circuit model at infinite temperature. Our results recover the correct transport exponent describing ballistic, superdiffusive, and diffusive transport in different regimes of the model. We also demonstrate anomalous transport encoded by a self-similar scaling form of the moment-generating function outside of the ballistic regime. In particular, we confirm the breakdown of Kardar-Parisi-Zhang universality in higher-order transport cumulants at the isotropic point. Our work paves the way for process-tensor descriptions of non-Markovian open
quantum systems to address current fluctuations in strongly interacting systems far from
equilibrium.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Effects of monitoring on entanglement dynamics for $1+1$D $\mathbb Z_2$ lattice gauge theory
Nilachal Chakrabarti, Nisa Ara, Neha Nirbhan et al. (+2 more)
The $(1+1)$-dimensional $\mathbb Z_2$ gauge theory is the simplest model that allows for
quantum simulation to probe the fundamental aspects of a gauge theory coupled with dynamical
fermions. To reliably
benchmark such a system, it is crucial to understand the non-
unitary quantum dynamics arising from effective non-Hermitian
evolution and post-selected monitoring protocols. This work focuses on the post-selected non-Hermitian filtering dynamics of a $\mathbb Z_2$ gauge theory, where the non-Hermitian terms are associated with local and non-local gauge-invariant operators naturally present in the theory. We interpret the resulting dynamics as post-selected filtering, where different operator sectors are coupled to loss channels with different rates. This gives a unified framework for both the local electric flux and particle-number terms and the non-local mesonic hopping term. Tensor network calculations are performed to probe the effect of the filtering for larger
lattice sizes (up to 256-site systems). Using
Matrix Product State calculations, the dynamics of
entanglement entropy are studied as a function of the filtering rate and the coupling constant. We find that, under both local and non-local filtering, the late-time saturation value of the bipartite
entanglement entropy remains independent of system size, providing no evidence of a measurement-induced phase transition-like phenomenon in the post-selected dynamics across the range of filtering strengths,
evolution times, and system sizes considered here.
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All authors Nilachal Chakrabarti, Nisa Ara, Neha Nirbhan, Arpan Bhattacharyya, Indrakshi Raychowdhury
Quantum Gases
Optical creation of dark-bright soliton lattices in one-dimensional multicomponent Bose-Einstein condensates
Y. Braver, D. Burba, Th. Busch et al. (+2 more)
We present a widely accessible and experimentally realizable technique for the controlled creation of dark-bright
solitons and
soliton lattices in one-dimensional atomic Bose-Einstein condensates. The method is based on preparing the condensate in a dark state of a $\Lambda$-coupled three-level system. Numerical simulations of the corresponding two-component system reveal that individual dark-bright
solitons created through this scheme can survive over experimentally accessible timescales, even when the coupling
laser fields are switched off. Meanwhile, the fate of
soliton lattices upon the quench of the fields depends on the scattering lengths. When they are all equal, the
lattice is found to persist on timescales comparable to the condensate lifetime, even though the analysis of dynamical stability reveals that they possess unstable modes. In this case the resulting destabilization is not found to be detrimental, as it leads to recurrent dynamics. However, for unequal scattering lengths the
lattice structure gets destroyed once the instability sets in, which happens after a few tens of milliseconds after the quench of the optical fields.
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All authors Y. Braver, D. Burba, Th. Busch, G. Juzeliūnas, P. G. Kevrekidis
Strongly Correlated Electrons
Fractionalization from Kinetic Frustration in Doped Two-Dimensional SU(4) Quantum Magnets
Wilhelm Kadow, Ivan Morera, Eugene Demler et al. (+1 more)
Separating electrons into emergent fractional quasiparticles is a hallmark of exotic
quantum phases of matter with strong interactions. Understanding under which circumstances fractionalized excitations appear is a major conceptual challenge and can help realize long sought-after states, such as
quantum spin liquids. Here, we identify a distinct mechanism for fractionalization. Starting from the plaquette-ordered ground state of an SU(4) symmetric t-J model at quarter filling on frustrated triangular
lattices, we reveal a compelling interplay between order and fractionalization as a function of doping. For hole doping, we find that the kinetic frustration can be relieved by fractionalizing the holes into fermionic spinons and bosonic holons: the holons minimize their kinetic energy when the spinons form a spinon
Fermi surface. We support this mechanism analytically in the large-N limit as well as numerically by simulating the SU(4) case with
matrix product states on cylinder geometries and with variational Monte Carlo methods on system sizes up to 40x40. Conversely, electron doping drives the system into a
ferromagnetic phase, akin to Nagaoka's
theorem. We discuss possible experimental realizations in moiré
heterostructures as well as ultracold atoms, and propose dynamical probes to search for key characteristics of the fractionalized quasiparticles.
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All authors Wilhelm Kadow, Ivan Morera, Eugene Demler, Michael Knap
Statistical Mechanics · Cross-listed from quant-ph
Non-stabilizerness and U(1) symmetry in chaotic many-body quantum systems
Daniele Iannotti, Angelo Russotto, Barbara Jasser et al. (+2 more)
We present exact, closed-form results for the non-stabilizerness of random pure states subject to a U(1)
symmetry constraint. Using stabilizer
entropy as our non-stabilizerness monotone, we derive the average and the variance for U(1)-constrained Haar random states. We show that the presence of a conserved charge leads to a substantial suppression of non-stabilizerness (magic) compared to the unconstrained case, and identify a qualitative difference between
entanglement and magic response. In the thermodynamic limit, stabilizer
entropy exhibits a different leading-order scaling close to a vanishing relative charge density, implying that magic is more robust to charge density fluctuations than
entanglement entropy. We test our analytical predictions against midspectrum eigenstates of two chaotic many-body systems with conserved U(1) charge: the complex-
fermion Sachdev-Ye-Kitaev (cSYK) model and a Heisenberg XXZ chain with next-to-nearest-neighbour couplings and conserved magnetization. We find an excellent agreement for the non-local cSYK model and systematic deviations for the local XXZ chain, highlighting the role of interaction locality.
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All authors Daniele Iannotti, Angelo Russotto, Barbara Jasser, Jovan Odavić, Alioscia Hamma
Strongly Correlated Electrons
Andreas Feuerpfeil, Atanu Maity, Ronny Thomale et al. (+2 more)
We investigate
Higgs criticality in candidate U(1) Dirac
spin liquids across a family of depleted triangular
lattices: the triangular, kagome, and maple-leaf geometries. For each, we identify the
symmetry-allowed spinon-pairing channel connecting the U(1) state to a proximate $\mathbb{Z}_2$
spin liquid, deriving the corresponding
quantum electrodynamics (QED$_3$)-
Higgs theory. While the triangular and kagome
lattices share a low-energy description with $N_f=4$ Dirac
fermions, the maple-leaf
lattice yields an analogous theory with $N_f=12$ and a distinct nodal structure where the Dirac cones can move along high-
symmetry lines in momentum space instead of gapping out. Using a large-$N_{f,b}$ expansion, we compute critical exponents and the scaling dimensions of the
symmetry-allowed Yukawa couplings. Although
Higgs-field fluctuations and a large
fermion flavor number strongly suppress the Yukawa coupling—pushing the maple-leaf
lattice closer to stability than its counterparts—we find that the coupling remains relevant at leading order in all three cases, substantially reducing its scaling dimension on the maple-leaf
lattice and asymptotically breaking Lorentz and conformal invariance. Ultimately, our results provide a unified framework demonstrating how the interplay between
fermion flavor count and nodal geometry dictates the fate of the QED$_3$-
Higgs transition.
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All authors Andreas Feuerpfeil, Atanu Maity, Ronny Thomale, Yasir Iqbal, Subir Sachdev
Statistical Mechanics · Cross-listed from hep-th
Maximally heavy dynamics in the causal diamond
David Poland and Gordon Rogelberg
Correlation functions of CFT operators with infinite scaling dimension are rich, multifaceted objects that describe physics ranging across classical holography, black hole dynamics, and flat-space scattering amplitudes. In this work, we provide a rigorous framework for characterizing the space of four-point functions of identical operators with infinite dimension in terms of well-defined “maximally heavy observables,” which are akin to intrinsic quantities describing statistical systems in the thermodynamic limit. These observables are highly constrained by crossing
symmetry and unitarity, and give novel insights into the locality of bulk states through the emergence of dynamical phase transitions. In certain cases, these results connect directly to the more familiar picture of
torus partition functions at large central charge. We apply our framework to a number of illustrative examples including generalized free fields,
chiral product correlators, and maximal
giant gravitons in planar $\mathcal{N}=4$ SYM.
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Strongly Correlated Electrons
Symmetry-Fractionalized Skin Effects in Non-Hermitian Luttinger Liquids
Christopher Ekman, Emil J. Bergholtz and Paolo Molignini
In one dimension, strongly correlated gapless systems are highly constrained due to conformal invariance, leading to the decoupling of low energy degrees of freedom corresponding to different
symmetry sectors. The most familiar example of this is
spin-charge separation. Here, we extend this mechanism to the non-Hermitian realm by demonstrating that skin effects corresponding to different
symmetry sectors exhibit an emergent decoupling. We establish this for $N$
flavor fermions and demonstrate it numerically for the special case of the Hubbard model, in which
spin and charge skin effects separate at low energies. Finally, we construct an interaction-enabled $E_8$ skin effect with no free
fermion counterpart.
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Mesoscale and Nanoscale Physics · Cross-listed from physics.chem-ph
Quantum Coherence Governs Macroscopic Polymorphism in Organic Semiconductors
Hai Wang, Tianhong Huang, Jiawei Chang et al. (+1 more)
Polymorphism in organic
semiconductors is conventionally framed as
equilibrium thermodynamic selection, yet atmospheric-pressure vapor deposition routinely produces metastable phases that defy classical nucleation theory. We develop a
symmetry-resolved open
quantum system formulation of
quantum dissipative assembly (QDA), in which the fundamental assembly unit is a vibronic wavepacket whose internal degrees of freedom are classified by the irreducible representations of the molecular point group. The carrier-gas environment acts as a structured dissipative bath with irrep-resolved spectral densities, and polymorph selection corresponds to relaxation into a
symmetry-resolved maximum-transmittance attractor (MTA) rooted in
quantum scattering theory and impedance matching. Guided by this theory, we tune the carrier-gas dissipative environment via reactor geometry, flow velocity, and precursor concentration to selectively synthesize a previously unreported polar polymorph of copper phthalocyanine, omega-CuPc, crystallizing in space group P2 with a dimerized
bilayer superstructure and an extreme Davydov splitting of 154 nm. Further structural refinement with a 4-molecule modulated supercell model resolves the majority of discrepancies between powder X-ray diffraction and energy minimization, revealing secondary layer orientation modulation as a higher-order dissipative optimization product. The framework consistently explains the formation windows of the eta, alpha, and beta polymorphs, their distinct morphologies, and the marked difference in crystalline order between open-shell CuPc and closed-shell NiPc. Our findings establish a
symmetry-guided, environment-controlled polymorph engineering strategy rooted in QDA, where the carrier-gas atmosphere serves as an active dissipative medium shaping the
symmetry-resolved dissipative landscape rather than acting as an inert thermal bath.
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All authors Hai Wang, Tianhong Huang, Jiawei Chang, Wenbo Zhang
Mesoscale and Nanoscale Physics
Topological Optical Chirality Dichroism
Wojciech J. Jankowski, Giandomenico Palumbo and Robert-Jan Slager
We report on a universal topological dichroism of
chiral three-dimensional systems in response to the chirality of light. We show that
chiral topological invariants result in integer-quantized dichroic excitation rate differences. Moreover, we demonstrate that such topological effects arise more generally from coupling optical chirality to higher tensor Berry
curvatures and Dixmier-Douady invariants of
quantum states, including
Hopf indices. We finally propose an experimental setup that leverages superchiral light as a smoking-gun probe of
chiral band
topologies in three-dimensional materials. Our findings establish an optical route for probing to date unobserved
chiral electronic band
topologies.
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Soft Condensed Matter
From Double Colloidal Networks to Core-Shell and Mixed Composites through Sequential Gelation
Alexander Kaltashov and Safa Jamali
Multicomponent gel systems have garnered much interest due to their compelling mechanical properties in the past decade. Yet, some mechanisms associated with multicomponent gels, such as sequential gelation, have been explored primarily in the context of chemical nonreversible polymeric and
protein gels than in physical reversible colloidal ones. In this study, we use mesoscale simulation techniques to model the sequential gelation of two-component colloidal systems whose components' interspecies and intraspecies electrostatic interactions can be modified independently. We show that by simply leveraging temporal control and interspecies interactions, we can construct markedly different networks; from double networks to mixed and core-shell composite structures of varying coarseness and heterogeneity natures. These findings present a compelling case for further exploration of multicomponent colloidal systems.
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Materials Science
Pentagonal PdTe2 Monolayer for Sustainable Solar-driven Hydrogen Production
Narender Kumar, Shambhu Bhandari, Dario Alfè et al. (+2 more)
This investigation demonstrates that the pentagonal PdTe$_2$ (penta-PdTe$_2$) monolayer is a highly tunable two-dimensional (2D) photocatalyst, characterized by a bandgap of 1.87~eV and high hole mobility. Using density functional theory (DFT) calculations with the HSE06 functional, we show that tensile strain engineering, particularly at $+2%$ and $+3%$, is essential for enabling spontaneous water splitting. At these strain values, the valence-band maximum (VBM) and conduction-band maximum (CBM) straddle the water redox potentials ($\mathrm{H^+/H_2}$ and $\mathrm{O_2/H_2O}$) under both acidic ($\mathrm{pH}=0$) and neutral ($\mathrm{pH}=7$) conditions. The monolayer's low hole effective mass facilitates rapid charge extraction, mitigating electron–hole recombination and promoting the oxygen
evolution reaction (OER) more effectively than many hexagonal and pentagonal counterparts. The Gibbs free energy ($\Delta G$) pathways indicate that the overpotentials for the hydrogen
evolution reaction (HER) and OER are highly sensitive to mechanical deformation, specifically biaxial strain. In particular, a tensile strain of $+3%$ yields an optimized balance of overpotentials, with $\eta_{\mathrm{HER}} = 0.70~\mathrm{V}$ at $\mathrm{pH}=0$ and $\eta_{\mathrm{OER}} = 0.72~\mathrm{V}$ at $\mathrm{pH}=7$. Finally, integrating optical absorption with thermodynamic driving forces results in a
solar-to-hydrogen (STH) efficiency of $20.40%$ at $\mathrm{pH}=7$. This performance exceeds that of several previously reported two-dimensional catalysts, positioning penta-PdTe$_2$ as a superior candidate for sustainable,
solar-driven hydrogen production.
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All authors Narender Kumar, Shambhu Bhandari, Dario Alfè, Nacir Tit, Ravindra Pandey
Mesoscale and Nanoscale Physics
Observation of Floquet-induced gap in graphene
Fei Wang, Xuanxi Cai, Xiao Tang et al. (+8 more)
Floquet engineering provides a powerful pathway for creating non-
equilibrium phases of matter with tailored electronic structures and properties through time-periodic driving. As the original theoretical prototype,
graphene established the framework in which the Floquet topological
insulator with light-induced anomalous
Hall effect was proposed. However, the defining spectroscopic signature of Floquet engineering in
graphene–light-induced hybridization (avoided-crossing) gap at Floquet band crossings, has remained experimentally elusive. Here, we report direct observation of Floquet-induced hybridization gap in monolayer
graphene under resonant driving by a strong light field. Time- and angle-resolved photoemission spectroscopy reveals gap opening at Floquet band crossings, accompanied by coherent Floquet sidebands. The gap exhibits pronounced momentum anisotropy, featuring two Dirac nodes protected by the spatiotemporal
symmetry and tunable by light polarization. These results provide long-sought experimental demonstration of Floquet band engineering in
graphene, opening up opportunities for light-field engineered
quantum phases in
graphene and related materials.
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All authors Fei Wang, Xuanxi Cai, Xiao Tang, Jinxi Lu, Wanying Chen, Tianshuang Sheng, Runfa Feng, Haoyuan Zhong, Hongyun Zhang, Pu Yu, Shuyun Zhou
Mesoscale and Nanoscale Physics
Robust Floquet-induced gap in irradiated graphite
Fei Wang, Xuanxi Cai, Wanying Chen et al. (+6 more)
Floquet engineering provides an emerging pathway for tailoring the electronic states of
quantum materials through time-periodic drive. A critical step along this direction is achieving light-induced modifications of the dynamical electronic structure, such as avoided-crossing gap at the Floquet Brillouin zone boundary, via efficient coupling of electrons with the coherent light-field. Here, we report robust Floquet-induced gap in bulk graphite that persists despite the presence of interlayer coupling and photo-excitation. Using time- and angle-resolved photoemission spectroscopy with intense mid-infrared pumping, we directly reveal Floquet-induced gaps at resonance points both in the valence and conduction bands, accompanied by coherent Floquet sidebands. The gap and sidebands coexist with photo-excited carriers, yet their distinct timescales allow us to disentangle their origins. Our demonstration of robust Floquet-induced gaps establishes graphite as a platform for coherent manipulation of Dirac
fermions and realization of light-engineered
quantum phases.
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All authors Fei Wang, Xuanxi Cai, Wanying Chen, Jinxi Lu, Tianshuang Sheng, Xiao Tang, Jiansong Li, Hongyun Zhang, Shuyun Zhou
Disordered Systems and Neural Networks
Quantum Beats in Many-Body Localized Systems
Bernard Faulend, Hrvoje Buljan and Antonio Štrkalj
Slow particle dynamics observed numerically even deep inside the many-body localized (MBL) regime has called the stability of MBL in the thermodynamic limit into question, and its microscopic origin remains unknown. Here, we show that this slow dynamics originates from many-body
quantum beats that arise from the interaction-induced modulation of oscillations associated with single-particle hopping processes. We relate this mechanism to local integrals of motion (LIOMs) and show that it survives at arbitrarily large distances between LIOMs, is consistent with the stability of MBL in the thermodynamic limit, and is generic to many-body systems. We present new numerical results for quasiperiodic potentials and, based on the
quantum beats mechanism, develop an analytical model that explains number
entropy growth and quasiparticle spreading, as well as clarifies the distinct MBL phenomenology observed in quasiperiodic and random potentials. Lastly, we propose concrete signatures for observing many-body
quantum beats in existing experimental platforms.
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Strongly Correlated Electrons
Categorical Time-Reversal Symmetries
Rui Wen and Sakura Schafer-Nameki
The classification of phases using categorical
symmetries has greatly expanded the landscape of gapped and gapless phases. So far, however, these developments have largely been restricted to phases with
unitary (higher-)categorical
symmetries over $\mathbb{C}$. In this work, we incorporate anti-
unitary symmetries, such as time-reversal
symmetry $\mathbb{Z}_2^T$, and show that the relevant physical structures are naturally described by fusion categories over $\mathbb{R}$. A class of real fusion categories, which we call Galois-real fusion categories, provides the correct categorical model for anti-
unitary symmetries. A simple example is the time-reversal
symmetry $\mathbb{Z}_2^T$ itself. We discuss the basic structures of real fusion categories and present a range of examples, including the group-theoretical categories $(G^T)^{\omega}$ and $\mathsf{Rep}(G^T)$ associated to anti-linear groups $G^T$, as well as non-invertible time-reversal
symmetries described by a real analogue of Tambara–Yamagami fusion categories. We then classify gapped phases enriched with anti-linear
symmetries in terms of module categories over Galois-real fusion categories. We furthermore apply the categorical formulation to prove dualities (i.e. gauge or Morita equivalences) of anti-linear
symmetries generated by gauging subgroups. Complementing this, we also develop a
Symmetry Topological Field Theory (SymTFT) framework, in which Galois-real fusion categories arise as boundary conditions of a $\mathbb{Z}_2^T$-enriched SymTFT. Morita equivalent anti-linear
symmetries are shown to arise as different boundaries of the same $\mathbb{Z}_2^T$-enriched SymTFT.
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Soft Condensed Matter
Phenol release from pNIPAM hydrogels: Scaling Molecular Dynamics simulations with Dynamical Density Functional Theory
H. A. Pérez-Ramírez, A. Moncho-Jordá and G. Odriozola
We employed molecular dynamics simulations (MD) and Bennett's acceptance ratio method to compute the free energy of transfer (Delta G_trans) of phenol, methane, and 5-fluorouracil (5-FU) between bulk water and water-pNIPAM mixtures with different
polymer volume fractions (phi_p). To this end, we first calculate the solvation free energies in both media to obtain Delta G_trans. Phenol and 5-FU (a drug used in cancer treatment) adsorb onto the pNIPAM surface and exhibit negative values of Delta G_trans irrespective of temperature, both above and below the lower critical solution temperature (T_c) of pNIPAM. In contrast, methane changes the sign of Delta G_trans, being positive below and negative above T_c. In all cases, and in contrast with some theoretical predictions, Delta G_trans shows a linear dependence on pNIPAM concentration up to high
polymer densities. We also compute the
diffusion coefficient (D) of phenol in water-pNIPAM mixtures as a function of phi_p in the dilute limit. Both Delta G_trans and D as functions of phi_p are key inputs to estimate the release halftime of hollow pNIPAM microgels using dynamic density functional theory (DDFT). Our scaling approach reproduces the experimental value of 2200 s for microgels of 50 micrometer radius without a cavity, at phi_p approximately 0.83 and 315 K.
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Strongly Correlated Electrons · Cross-listed from physics.chem-ph
Hunting for quantum advantage in electronic structure calculations is a highly non-trivial task
Örs Legeza, Andor Menczer, Miklós Antal Werner et al. (+7 more)
In light of major developments over the past decades in both
quantum computing and simulations on classical hardware, it is a serious challenge to identify a real-world problem where
quantum advantage is expected to appear. In
quantum chemistry, electronic structure calculations of strongly correlated, i.e. multi-reference problems, are often argued to fall into such category because of their intractability with standard methods based on mean-field theory. Therefore, providing state-of-the-art
benchmark data by classical
algorithms is necessary to make a decisive conclusion when such competing development directions are compared. We report cutting-edge performance results together with high accuracy ground state energy for the Fe$_4$S$_4$ molecular cluster on a CAS(54,36) model space, a problem that has been included quite recently among the list of systems in the
Quantum Advantage Tracker webpage maintained by IBM and RIKEN. Pushing the limits even further, we also present CAS-SCF based orbital optimizations for unprecedented CAS sizes of up to 89 electrons in 102 orbitals [CAS(89,102)] for the Fe$_5$S$_{12}$H$_4^{5-}$ molecular system comprising twenty five open shell orbitals in its sextet ground state and an active spaces size of 331 electrons in 451 orbitals. We have achieved our results via mixed-precision
spin-adapted ab initio Density
Matrix Renormalization Group (DMRG) electronic structure calculations interfaced with the ORCA program package and utilizing the NVIDIA Blackwell graphics processing unit (GPU) platform. We argue that DMRG
benchmark data should be taken as a classical reference when
quantum advantage is reported. In addition, full exploitation of classical hardware should also be considered since even the most advanced DMRG implementations are still in a premature stage regarding utilization of all the benefits of GPU technology.
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All authors Örs Legeza, Andor Menczer, Miklós Antal Werner, Sotiris S. Xantheas, Frank Neese, Martin Ganahl, Cole Brower, Samuel Rodriguez Bernabeu, Jeff Hammond, John Gunnels
Superconductivity
An echo of the low-temperature phase competition and 1/8 dip in room-temperature properties of cuprate HTSCs
A. V. Fetisov
Cuprate high-temperature
superconductors (HTSCs) exhibit a characteristic dome-shaped dependence of the superconducting transition temperature on the charge carrier concentration, Tc(p), featuring a maximum at optimal doping p = 0.16. Near the p = 1/8 composition, a sharp suppression ("dip") of Tc occurs - conventionally referred to as the "1/8 anomaly" - which is widely attributed to charge and
spin ordering in the CuO2 planes. Here, we investigate the room temperature hydration of La2-xBaxCuO4 and YBa2Cu3O6+delta under a high-frequency
magnetic field and report anomalous weight changes during the initial stage of the process. For both compounds, the doping dependence of these weight fluctuations closely mirrors their respective Tc(p) profiles, including the signature "1/8 anomaly". The prominent manifestation of these characteristically low-temperature electronic features at room temperature provides critical insights into the stability of high-energy electronic correlations. These findings may offer a novel foundation for the development of theoretical models of cuprate superconductivity.
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Quantum Gases
Emergence of a molecular quantum liquid in one dimension
Rajashri Parida, Biswajit Paul, Harish S. Adsule et al. (+4 more)
We investigate the fate of a one-dimensional
lattice superfluid formed by hard-core
bosons, aka `atoms' (alternatively, a free spinless
Fermi sea) subjected to nearest-neighbor attractive Hubbard-like interactions only in subgroups of two sites. The system, as expected, stabilizes a fluid of dimerized molecules at large attractive interactions. However, the composite molecules have an effective meek hopping scale and dominant repulsive interactions solely due to virtual
quantum fluctuations. Interestingly, at an intermediate attractive potential, the system realizes a phase-separated region where the system is in an absorbing state. We show that this phase-separated region is due to an emergent attractive interaction between the dimers which leads to a local charge-density wave puddle where particles effectively cluster with local half-filling. Moreover the molecular superfluid gets spontaneously charge-ordered in the addition of an unpaired atom, reflecting the extreme sensitivity of the system to the existence of lone atoms. Using density-
matrix renormalization group studies and effective low-energy
Hamiltonians, we isolate the
quantum processes to uncover the physics behind molecule formation in a strongly interacting one-dimensional system.
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All authors Rajashri Parida, Biswajit Paul, Harish S. Adsule, Shovan Dutta, Diptiman Sen, Tapan Mishra, Adhip Agarwala