Disordered Systems and Neural Networks · Cross-listed from physics.chem-ph
A New Paradigm for Computational Chemistry
Raphael T. Husistein and Markus Reiher
Computational chemistry has become an indispensable tool for generating data and insights, pervading all branches of experimental chemistry. Its most central concept is the potential energy hypersurface, key to all chemistry and materials science, as it assigns an energy to a molecular structure, the necessary ingredient for reaction mechanism elucidation and reaction rate calculation. Density functional theory (DFT) has been the most important method in practice for obtaining such energies, which is mirrored in the use of high-performance computing hardware. In the last two decades, a new class of surrogate potential energy functions has been evolving with remarkable properties:
quantum accuracy combined with force-field speed. Until very recently, their application was hampered by the fact that they needed to be trained on truly large system-specific data sets, generated before a computational chemistry study could be started (in sharp contrast to DFT, which, as a first-principles method, works out of the box, but at a far higher price of computational cost). Very recently, this roadblock has been overcome by so-called foundation machine learning interatomic potentials, which are poised to completely change the way we do computational chemistry, likely prompting us to abandon DFT as the
prime method of choice for this purpose in less than a decade.
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Strongly Correlated Electrons · Cross-listed from hep-th
Solving Lévy Sachdev-Ye-Kitaev Model
Budhaditya Bhattacharjee, William. E. Salazar, Alexei Andreanov et al. (+1 more)
We present an exact solution in the large-$N$ limit of the Lévy Sachdev-Ye-Kitaev (LSYK) model introduced in Ref. [1], wherein the couplings are drawn from a Lévy Stable distribution parameterized by a tail exponent $\mu \in [0, 2]$. Starting from the
Hamiltonian and its associated partition function, we highlight the key differences from the standard Gaussian SYK model and derive the large-$N$ Schwinger-Dyson equations via a bosonic oscillator representation of the action. These equations are solved both numerically and analytically in the large-$q$ and infrared limits. We subsequently analyze the chaotic properties of the model by computing the Krylov exponent from the large-$q$ Green's function and extracting the Lyapunov exponent from the $4$-point function. The parameter $\mu$ continuously interpolates between a free theory at $\mu = 0$ and the conventional, maximally chaotic Gaussian SYK model at $\mu = 2$, with non-maximal chaos persisting throughout the intermediate regime $0 < \mu < 2$. Thermodynamic quantities, including the
entropy, free energy, average energy, and specific heat capacity, are computed and compared with their Gaussian SYK counterparts. The interpretations of the thermodynamics are discussed with respect to the
holographic dual and non-
Fermi liquid theory. Finally, we discuss an alternative representation of the LSYK model based on a distinct decomposition of the Lévy Stable distribution, which establishes a non-trivial connection to Gaussian SYK, and provide supporting analytical and numerical results in the appendices.
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All authors Budhaditya Bhattacharjee, William. E. Salazar, Alexei Andreanov, Dario Rosa
Materials Science
Enantiopurity-Controlled Magnetism in a Two-Dimensional Organic-Inorganic Material
P. Garrett Hegel, Oscar Gonzalez, Mingrui Li et al. (+6 more)
Extended solids that combine unpaired electron
spin and structural chirality can host unconventional
magnetic behaviors with potential for electronic technologies. A versatile strategy for creating
chiral solids is incorporation of
chiral organic molecules into inorganic
crystals. However, such hybrid organic-inorganic materials have so far been examined through the lens of absolute chirality, leaving enantiomeric excess (ee) underexplored as a tuning parameter. Here, we report two-dimensional (2D) intercalation compounds with controllable ee produced by cation exchange of MnPS$_3$ with
chiral organic molecules. We show that these materials' magnetism is determined by intercalant ee rather than absolute chirality. Moreover, low-ee materials display thermally activated dynamic magnetism absent from enantiopure analogs. These ee-dependent
magnetic behaviors are explained by local ordering of Mn vacancies, directed by correlated vacancy-intercalant electrostatics and confined molecular packing. Together, these results demonstrate a distinctive tuning strategy for molecule-material hybrids and establish design principles for 2D
chiral and magnetically dynamic materials.
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All authors P. Garrett Hegel, Oscar Gonzalez, Mingrui Li, Shannon S. Fender, Harishankar Jayakumar, Archana Raja, Ariana Ray, Isaac M. Craig, D. Kwabena Bediako
Statistical Mechanics · Cross-listed from quant-ph
Bootstrapping Symmetries in Quantum Many-Body Systems from the Cross Spectral Form Factor
Chen Bai, Zihan Zhou, Bastien Lapierre et al. (+1 more)
Symmetries play a central role in
quantum many-body physics, yet uncovering them systematically remains challenging. We introduce a bootstrap framework to reconstruct the representation theory of hidden finite group
symmetries of
quantum many-body
lattice Hamiltonians, using only a known
symmetry subgroup $N$ and spectral correlations between its sectors. We introduce the cross spectral form factor (xSFF) as a subgroup-resolved diagnostic of hidden
symmetry, computed via exact diagonalization to seed the bootstrap. Applying constraints from these data alongside the algebraic conditions of the fusion rules, our bootstrap sharply restricts candidate groups $G$. Without prior assumptions about $G$, our method can systematically recover its representation-theoretic data, including the number and dimensions of irreducible representations, their branching rules with respect to $N$, the fusion
algebra, and the full character table. This framework applies to chaotic and integrable systems and accommodates
unitary and anti-
unitary symmetries. Through examples, we demonstrate that $G$ can be uniquely identified. Our bootstrap recovers the $\mathbb{Z}_4$
symmetry at the self-dual point of the three-state
quantum torus chain, detects signatures of projective representations in the effective
Hamiltonian of the driven Bose-Hubbard model, and rediscovers the $\eta$-pairing $\mathrm{SO}(4)$
symmetry of the one-dimensional
Fermi-Hubbard model. Leveraging the universal random-
matrix ramp in chaotic systems, we demonstrate the possibility of ramp-only bootstrap alongside an example with hidden commuting
symmetries. We establish the xSFF as a diagnostic for conserved order parameters in a
symmetry-breaking
spin-$1$ chain and introduce an ancilla-assisted measurement
circuit for experimental realization. Our framework establishes a practical route to identify
symmetries from dynamical spectral observables.
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All authors Chen Bai, Zihan Zhou, Bastien Lapierre, Shinsei Ryu
Strongly Correlated Electrons
Chiral vortical effect and boundary-induced vortical pumping in finite Weyl systems
B. Q. Song and Pavan Hosur
The
chiral vortical effect (CVE) – an axial current driven by rotation in
chiral matter – appears in systems ranging from relativistic fluids to Weyl semimetals. We present an exact
quantum solution of a rotating Weyl
fermion in a finite cylinder. We recover the exact current density on the rotation axis obtained by Vilenkin and show that its cross-sectional average vanishes in the thermodynamic limit, establishing that the bulk vortical response is purely a magnetization current. For
spin-polarized boundary conditions, we uncover an additional effect beyond the known CVE: a robust family of
chiral modes that transport axial charge, $\Delta Q=\chi N^2,\Delta\theta/4\pi$, under rotation by angle $\Delta\theta$, where $\chi$ is the Weyl node chirality and $N$ is the number of
chiral modes. The pump is independent of temperature,
Fermi level, and Weyl velocities, but depends on the UV-sensitive number $N$. These results clarify the
quantum structure of the bulk CVE and reveal a boundary-enforced
chiral spectral structure underlying vortical response in Weyl systems.
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Statistical Mechanics · Cross-listed from physics.flu-dyn
Branching Paths Statistics for confined Flows : Adressing Navier-Stokes Nonlinear Transport
Daniel Yaacoub, Stéphane Blanco, Richard Fournier et al. (+4 more)
Recent advances have allowed to tackle exact path-space probabilistic representations of macroscopic advection-
diffusion models involving advection nonlinearities by step forward approaches in terms of continuous branching
stochastic processes. Yet, the need of such paradigm shift is huge for the broad flied of fluid flows. In deed, wherever for
climate dynamics, engeenering, geophysical and planetary formations, or biomedical applications, complex transport phenomena involving
diffusion and advection in confined domains set the physics. In this work, we advance this framework by casting such branching representations within the class of Navier-Stokes strongly nonlinear transport. This yields novel propagator representations for fluid dynamics and opens new routes for efficient simulations of fluids in confined domains by use of new Backward Monte Carlo
algorithms.
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All authors Daniel Yaacoub, Stéphane Blanco, Richard Fournier, Gerjan Hagelaar, Jean-François Cornet, Jérémi Dauchet, Thomas Vourc'h
Quantum Gases
Dissipative Floquet engineering of gapped many-body phases using thermal baths
Lorenz Wanckel and André Eckardt
Floquet engineering, the control of a
quantum system by means of time-periodic driving, allows to modify the properties of a system so that it is described by an approximate effective time-independent
Hamiltonian. However, in the presence of interactions the stabilization of interesting many-body ground states of such effective
Hamiltonians is possible only on a certain time scale, beyond which Floquet heating sets in, as it results from unwanted driving induced resonant excitation. Moreover, the preparation of the ground state of such Floquet engineered effective
Hamiltonians usually has to be accomplished adiabatically, which is another source of heating, especially when a phase transition has to be passed in a large system. Here, we propose a general dissipative strategy for the preparation and stabilization of effective ground states that are protected by an energy gap, such as topologically ordered states. It is scalable and relies on coupling the driven system to a thermal bath, the properties of which are chosen so that it both suppresses Floquet heating and guides the system into a non-
equilibrium steady state with a large occupation of the effective ground-state. The small residual occupations of effective excited states are non-thermal, reflecting the non-
equilibrium nature of the scheme. We use the Floquet-Born-Markov master equation to verify the proposed strategy. In particular, we discuss the preparation of both a one-dimensional Mott
insulator and a two-dimensional fractional Chern
insulator in strongly driven Bose-Hubbard systems.
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Statistical Mechanics
Temperature and integrability-breaking correspondence via adiabatic transformations
Hyeongjin Kim, Souvik Bandyopadhyay and Anatoli Polkovnikov
We reveal a correspondence between temperature and integrability-breaking in classical and
quantum many-body systems through the lens of geometry and adiabatic transformations. Decreasing the temperature, obtained in a standard way through the derivative of
entropy with respect to energy, steers the system towards an integrable point despite strong integrability-breaking interactions. Auto-correlation functions of local observables exhibit slow relaxation dynamics, which violates ergodicity on the approach to this integrable point. Subsequently, the average fidelity susceptibility of stationary states satisfies scaling relations near the integrable point, in close analogy with continuous phase transitions. We further find that the dynamical exponent encompassing relaxation can be different in the
quantum and classical models, depending on dimension of the systems. Collectively, our results establish temperature as a tunable control parameter for chaos and puts it on equal footing with integrability-breaking perturbations.
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Strongly Correlated Electrons
Electronic structure and correlation of La$_4$Co$_2$NiO$_8$Cl$_2$: a theoretical proposal for a La$_4$Ni$_3$O$_{10}$-like high-temperature superconductor
Si-Yong Jia, Jing-Xuan Wang, Jian-Hong She et al. (+2 more)
Based on the discovery of high-temperature superconductivity in the
bilayer nickelate La$_3$Ni$_2$O$_7$, several Co-based La$_3$Ni$_2$O$_7$-like materials were theoretically predicted as possible high-temperature
superconductors by electron doping. Motivated by these findings and the subsequent discovery of superconductivity in the trilayer nickelate La$_4$Ni$_3$O$_{10}$ under high pressure, we propose and investigate a Co-based La$_4$Ni$_3$O$_{10}$-like material. With electron doping to the high-pressure trilayer cobaltate La$_4$Co$_3$O$_{10}$, using density functional theory combined with dynamical mean-field theory (DFT+DMFT), we find that the resulting compound La$_4$Co$_2$NiO$_8$Cl$_2$ exhibits a
crystal structure and a strongly correlated electronic structure similar to those of La$_4$Ni$_3$O$_{10}$ under high pressure. This suggests that this new compound may host high-temperature superconductivity.
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All authors Si-Yong Jia, Jing-Xuan Wang, Jian-Hong She, Rong-Qiang He, Zhong-Yi Lu
Other Condensed Matter · Cross-listed from quant-ph
Conditional channel entropy sets fundamental limits on thermodynamic quantum information processing
Himanshu Badhani and Siddhartha Das
The thermodynamic resourcefulness of
quantum channels primarily depends on their underlying causal structure and their ability to generate
quantum correlations. We quantify this interplay within the resource theory of athermality for bipartite
quantum channels in the presence of a side channel acting as
memory, referred to as the resource theory of conditional athermality. For channels with trivial output
Hamiltonians, we characterize the optimal one-shot rates for distilling the identity gate from a given channel, as well as the cost of simulating the channel using the identity gate, under conditional Gibbs-preserving superchannels. We show that these rates have a direct trade-off relation with the conditional channel
entropies, attributing operational significance to signaling in
quantum processes. Furthermore, we establish an asymptotic equipartition property for the conditional channel min-
entropy for classes of channels that are either tele-covariant or no-signaling from the non-conditioning input to the conditioning output. As a consequence, we demonstrate asymptotic reversibility of the resource theory for these channels. The asymptotic conditional athermality capacity of a tele-covariant channel is half the superdense coding capacity of its Choi state. Our work establishes the conditional channel
entropy as a primitive information-theoretic concept for
quantum processes, elucidating its potential for wider applications in
quantum information science.
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Statistical Mechanics · Cross-listed from physics.soc-ph
Message passing and cyclicity transition
Takayuki Hiraoka
Message passing, also known as belief propagation, is a versatile framework for analyzing models defined on graphs. Its most prototypical application is percolation; yet, the interpretation of the message passing formulation of percolation remains elusive. We show that the message passing solutions commonly associated with the probability of belonging to the
giant component actually identify reachability from cycles. This interpretation generally applies to bond and site percolation on any directed or undirected networks. Our findings highlight the distinction between transition in cyclicity and the emergence of the
giant component.
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Statistical Mechanics · Cross-listed from quant-ph
Learning and Generating Mixed States Prepared by Shallow Channel Circuits
Fangjun Hu, Christian Kokail, Milan Kornjača et al. (+5 more)
Learning
quantum states from measurement data is a central problem in
quantum information and computational complexity. In this work, we study the problem of learning to generate mixed states on a finite-dimensional
lattice. Motivated by recent developments in mixed state phases of matter, we focus on arbitrary states in the trivial phase. A state belongs to the trivial phase if there exists a shallow preparation channel
circuit under which local reversibility is preserved throughout the preparation. We prove that any mixed state in this class can be efficiently learned from measurement access alone. Specifically, given copies of an unknown trivial phase mixed state, our
algorithm outputs a shallow local channel
circuit that approximately generates this state in trace distance. The sample complexity and runtime are
polynomial (or quasi-
polynomial) in the number of
qubits, assuming constant (or polylogarithmic)
circuit depth and gate locality. Importantly, the learner is not given the original preparation
circuit and relies only on its existence. Our results provide a structural foundation for
quantum generative models based on shallow channel
circuits. In the classical limit, our framework also inspires an efficient
algorithm for classical
diffusion models using only a
polynomial overhead of training and generation.
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All authors Fangjun Hu, Christian Kokail, Milan Kornjača, Pedro L. S. Lopes, Weiyuan Gong, Sheng-Tao Wang, Xun Gao, Stefan Ostermann
Soft Condensed Matter
Polyelectrolyte adsorption at the solid-liquid interface favors receding contact line instability
Léa Delance, Diego Díaz, Arivazhagan G. Balasubramanian et al. (+3 more)
Controlling the motion of non-Newtonian drops on surfaces is crucial for applications ranging from inkjet printing to biomedical devices and food processing. While the macroscopic behavior of viscoelastic drops sliding on tilted hydrophobic surfaces has been characterized, showing reduced velocities and elongation compared to Newtonian fluids, the underlying microscopic mechanisms remain poorly understood. To address this gap, we developed a high-speed, high-resolution reflection microscope that enables direct visualization of the contact line of sliding drops. We used water/soluble polyelectrolyte solutions based on polyacrylamide and let drops sliding on hydrophobic substrates composed of Teflon AF- and PDMS-coated glass slides. The substrate tilting angle was varied between 20{\deg} and 45{\deg}. We reveal how viscoelasticity influences the dynamics of the receding contact line and drop motion. Our experiments demonstrate that viscoelasticity can destabilize the receding contact line, triggering filament formation. This instability previously observed in the coating of thin viscoelastic films, is reported here for the first time in sliding drops. We further highlight the critical role of
polymer charge in this process: while cationic and non-ionic
polymers promote filament formation, anionic
polymers do not, a difference we attribute to the distinct wetting properties of the solutions. In conclusion, we clarify the interplay between rheology, surface interactions, and drop dynamics.
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All authors Léa Delance, Diego Díaz, Arivazhagan G. Balasubramanian, Outi Tammisola, Kaloian Koynov, Hans-Jürgen Butt
Statistical Mechanics · Cross-listed from hep-th
Infinite Heat Order in 3+1 Dimensions
Borut Bajc, Giulia Muco, Francesco Sannino et al. (+1 more)
We investigate whether spontaneous
symmetry breaking can persist up to arbitrarily high temperature in ultraviolet-complete
quantum field theories in four spacetime dimensions. We focus on completely asymptotically free models with gauge group $\mathrm{SU}(N_{c1})\times \mathrm{SU}(N_{c2})$ and two complex scalar fields, each transforming in the fundamental representation of one gauge factor and singlet under the other. The scalar potential contains quartic self-interactions together with a negative portal coupling between the two sectors. In the Veneziano limit, this class of theories was previously shown to admit fixed-flow trajectories for which one scalar acquires a negative thermal mass at asymptotically large temperature, leading to
symmetry non-restoration. Here we extend that analysis to finite numbers of colours and flavours. We derive the finite-$N$ fixed-flow equations, compute the leading $1/N$ corrections to the large-$N$ solutions, and solve the full finite-$N$ system numerically. We find explicit finite-$N$
benchmark theories for which the scalar potential remains bounded from below, the gauge sector is asymptotically free, and one scalar thermal mass stays negative at arbitrarily high temperature. This provides an explicit perturbative example of infinite heat order in a four-dimensional ultraviolet-complete
quantum field theory with a finite field content.
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All authors Borut Bajc, Giulia Muco, Francesco Sannino, Sophie Wagner
Materials Science · Cross-listed from cs.LG
Bridging the Simulation-to-Experiment Gap with Generative Models using Adversarial Distribution Alignment
Kai Nelson, Tobias Kreiman, Sergey Levine et al. (+1 more)
A fundamental challenge in science and engineering is the simulation-to-experiment gap. While we often possess prior knowledge of physical laws, these physical laws can be too difficult to solve exactly for complex systems. Such systems are commonly modeled using simulators, which impose computational approximations. Meanwhile, experimental measurements more faithfully represent the real world, but experimental data typically consists of observations that only partially reflect the system's full underlying state. We propose a data-driven distribution
alignment framework that bridges this simulation-to-experiment gap by pre-training a generative model on fully observed (but imperfect) simulation data, then aligning it with partial (but real) observations of experimental data. While our method is domain-agnostic, we ground our approach in the physical sciences by introducing
Adversarial Distribution
Alignment (ADA). This method aligns a generative model of atomic positions – initially trained on a simulated Boltzmann distribution – with the distribution of experimental observations. We prove that our method recovers the target observable distribution, even with multiple, potentially correlated observables. We also empirically validate our framework on synthetic, molecular, and experimental
protein data, demonstrating that it can align generative models with diverse observables. Our code is available at https://kaityrusnelson.com/ada/.
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All authors Kai Nelson, Tobias Kreiman, Sergey Levine, Aditi S. Krishnapriyan
Other Condensed Matter · Cross-listed from quant-ph
Variational Dynamics of Open Quantum Spin Systems in Phase Space
Jacopo Tosca, Zejian Li, Francesco Carnazza et al. (+1 more)
We introduce a variational method for simulating the dynamics of interacting open
quantum spin systems. The method is based on the
spin phase-space representation and variationally targets the Husimi-$Q$ function with an ansatz based on a multi-dimensional mixture of
spin-coherent states. Crucially, the mixture coefficients are allowed to take negative values, enabling the faithful capture of
quantum correlations beyond semiclassical descriptions. The resulting equations of motion are derived from the Dirac-Frenkel variational principle and can be evaluated efficiently without resorting to Monte Carlo sampling by exploiting the analytical structure of the ansatz. As a first application, we demonstrate that this approach accurately captures both the full
quantum dynamics and the non-
equilibrium steady states of the transverse-field
quantum Ising model, in excellent agreement with exact diagonalization. Furthermore, we show that the method scales efficiently to large two-dimensional
lattices, a regime that remains challenging for other techniques.
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All authors Jacopo Tosca, Zejian Li, Francesco Carnazza, Cristiano Ciuti
Quantum Gases · Cross-listed from quant-ph
Thermal Entanglement and Out-of-Equilibrium Thermodynamics in 1D Bose gases
Julia Mathé, Nicky Kai Hong Li, Pharnam Bakhshinezhad et al. (+1 more)
We investigate
entanglement in and out of
equilibrium in a one-dimensional Bose gas in its low-energy Bogoliubov regime. In this Gaussian setting, the state is fully characterized by its covariance
matrix, which allows us to detect and quantify
entanglement using a covariance-based framework and associated
entanglement monotones. For thermal states, we determine the optimal
entanglement witness arising from the covariance
matrix criterion and show that it has a remarkably simple mode-resolved structure: it is diagonal in the normal-mode basis and admits a simple analytic form that can be expressed as a product of only two normal-mode uncertainties. We then study out-of-
equilibrium dynamics induced by
unitary compression and show that
entanglement can be generated even from initially separable thermal states. When the
evolution is fully adiabatic, the optimal witness retains the same two-mode structure as in the thermal case. Departing from this regime, i.e., performing increasingly rapid compression, the optimal witness becomes genuinely more intricate. Our methods and results provide a unified and physically intuitive picture of how
entanglement emerges and evolves in 1D
quantum Bose gases, and identify an optimal witness structure relevant more broadly to the analysis of
entanglement in quadratic bosonic models and its role in thermodynamic cycles.
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All authors Julia Mathé, Nicky Kai Hong Li, Pharnam Bakhshinezhad, Giuseppe Vitagliano
Mesoscale and Nanoscale Physics
FerBo: a noise resilient qubit hybridizing Andreev and fluxonium states
J. J. Caceres, D. Sanz Marco, J. Ortuzar et al. (+6 more)
We propose a novel superconducting
quantum circuit that should be robust against both relaxation and dephasing over a wide and experimentally accessible parameter range. The
circuit consists of a parallel arrangement of a large inductance, a small capacitor, and a well-transmitting Josephson weak link. Protection against relaxation arises from the hybridization between the fermionic degree of freedom associated with Andreev levels in the weak link and the bosonic electromagnetic mode of the LC
circuit, hence its name: FerBo. Furthermore, as in the fluxonium
qubit, delocalization of the wavefunctions in phase space provides resilience against dephasing.
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All authors J. J. Caceres, D. Sanz Marco, J. Ortuzar, E. Flurin, C. Urbina, H. Pothier, M. F. Goffman, F. J. Matute-Cañadas, A. Levy Yeyati
Statistical Mechanics
Principal component analysis of wavefunction snapshots in non-equilibrium dynamics
Dharmesh Yadav, Devendra Singh Bhakuni and Bijay Kumar Agarwalla
We study non-
equilibrium quantum dynamics by performing principal component analysis on the data sets of wavefunction snapshots. We show that a specific transformation of the data sets maximizes the information content in the largest principal component and further enables its connection to certain observables. This connection enables us to explain the dynamical features revealed by such a dimensionality-reduction scheme. We demonstrate this using
quantum dynamics of the Heisenberg
spin chain, starting from different initial states, and further extend the approach to extract higher-order correlations. Our framework should also be applicable to other unsupervised machine-learning methods based on dimensionality-reduction schemes and is highly relevant to experiments with
quantum simulators, including those in higher dimensions.
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Materials Science · Cross-listed from physics.comp-ph
A multiphysics model for triboelectric nanogenerator design with explicit surface roughness representation
MD Tanzib Ehsan Sanglap, Jack Perris, Rudra Mukherjee et al. (+5 more)
The design of triboelectric nanogenerators (TENGs) for efficient energy harvesting requires predictive models that capture the interplay between surface roughness, real contact area, and electrostatic behaviour across diverse tribolayer materials and roughness levels. To address this demand, this paper presents a multiphysics finite element framework that couples mechanical contact analysis with electrostatic simulations, considering exact surface roughness representations rather than idealised statistical approximations. Compared with optical interference microscopy measurements, the framework predicts the real contact area ratio more accurately than analytical models. The proposed approach captures the electrostatic behaviour by scaling the TENG surface charge density with the real contact area ratio between the rough tribolayers, computed for a given mechanical load. This method improves agreement with experiments for open-
circuit voltage and capacitance relative to approximate analytical models. To represent the TENG
circuit, a time-dependent ordinary differential equation is integrated, enabling evaluation of electrical responses under varying load conditions and elucidating the roles of surface roughness, mechanical load, contact-separation frequency, and resistive load. The framework provides a robust, scalable tool for performance optimisation across dielectric materials, mechanical behaviours, and operating conditions and is readily extendable to other surface-dependent energy-harvesting devices.
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All authors MD Tanzib Ehsan Sanglap, Jack Perris, Rudra Mukherjee, Charchit Kumar, Lukasz Kaczmarczyk, Chris J. Pearce, Daniel M. Mulvihill, Andrei G. Shvarts
Soft Condensed Matter
High-symmetry ill-fitting subunits in 3D form aggregates of all dimensions
Elena N. Govorun and Martin Lenz
Proteins can combine into functional elements in living
cells or self-assemble into unwanted structures in a number of diseases. The resulting aggregates often display filamentous morphologies across a large range of
protein shapes and molecular interactions. This has led to the suggestion that filament formation could be a generic outcome of the aggregation of geometrically complex, ill-fitting objects, although such a mechanism has not been demonstrated in three dimensions. To address this problem, we theoretically study the self-assembly of three-dimensional identical, ill-fitting deformable subunits mimicking globular
proteins in solution. In our model, self-assembling subunits incur deformations that accumulate as the aggregate size increases and can eventually hamper further assembly. We analytically predict the ground state morphologies of the resulting aggregates as a function of the subunit adhesivity and elasticity by mapping their mechanics onto those of two incompatible, interconnected networks. We find that zero-dimensional clusters, three-dimensional bulks as well as
symmetry-broken one-dimensional filaments and two-dimensional layers can all form depending on assembly parameters. Poorly compressible, moderately adhesive subunits favor filaments. These findings hint at a generic pathway to control self-assembly in three dimensions and suggests that such mechanisms could be investigated in more realistic
protein models.
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Statistical Mechanics · Cross-listed from physics.bio-ph
Predictability can be dynamically constructed in deterministic systems
Lars Koopmans, Elinor M. Kay and Hyun Youk
A deterministic system's future can be fixed from the start yet remain unpredictable because of chaos or computational irreducibility. Here we reveal another source of unpredictability for non-chaotic deterministic systems: collective entities making the future legible are initially absent but dynamically constructed. In a generalized cellular automaton, disordered
lattices evolved into static configurations, rectilinear waves, or spiral waves. Although initial configurations fixed each fate, machine-learning models did no better than randomly guessing fates from them. Recoding
cell states geometrically revealed self-organization of prediction-enabling topological entities:
vortices, non-contractible-loop strings, and, most generally, a winding field describing how same-state regions wrap the
lattice. As the winding field self-organized, initially unpredictable fates became increasingly legible. Static and rectilinear-wave fates became progressively predictable, whereas spiral-wave fate became accurately predictable only near wave formation. These results establish that self-organization can build not merely order but entities that make certain futures visible, revealing a gap between determinism and practical predictability.
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Strongly Correlated Electrons
The multichannel Dyson equation for double ionisation spectroscopies
Pierre Sellié, J. Arjan Berger and Pina Romaniello
Several photoemission spectroscopies and, in particular, Auger spectroscopy, involve double-ionization processes. For the numerical simulation of these spectroscopies it is convenient to use the particle-particle channel of the two-body Green's functions since its poles correspond to excitation energies in which the final state has two more particles (holes or electrons) than the initial state. In standard approaches it is approximated within the random phase approximation. As a consequence only the quasiparticles of the photoemission spectrum are captured but none of the satellites features. In this work, we go beyond this approximation by employing the multichannel Dyson equation. By coupling the particle-particle two-body Green's function to the 3-hole-1-electron and 3-electron-1-hole channels of the four-body Green's function, the multichannel Dyson equation incorporates correlations beyond the RPA in a straightforward way. We are thus able to describe both quasiparticles and satellites in the photoemission spectra.
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Mesoscale and Nanoscale Physics
Simultaneous operation of an 18-qubit modular array in germanium
J.J. Dijkema, X. Zhang, A. Bardakas et al. (+8 more)
Utility-scale
quantum computing requires the integration and operation of a large-scale
qubit register.
Semiconductor spin qubits are a primary candidate for this, due to the prospects of building integrated hybrid
quantum-classical architectures. However, scaling
spin-
qubit systems while preserving performance and control has remained a challenge. Here, we demonstrate the operation of an 18-
qubit array in germanium based on an extendable 2xN architecture. We achieve simultaneous initialization, control, and readout across the entire array, enabled by parallel operation of modular unit
cells. Across the array, we achieve average and median single-
qubit gate fidelities of 99.8% and 99.9%, respectively. Finally, we characterize the nearest-neighbor exchange couplings throughout the device and implement high-quality controlled-Z gates to generate a three-
qubit Greenberger-Horne-Zeilinger (GHZ) state. These results demonstrate that
spin-
qubit arrays can be scaled while maintaining high-fidelity operation and establish a modular, extendable architecture for planar
semiconductor quantum processors.
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All authors J.J. Dijkema, X. Zhang, A. Bardakas, D. Bouman, A. Cuzzocrea, D. van Driel, D. Girardi, L.E.A. Stehouwer, G. Scappucci, A.M.J. Zwerver, N.W. Hendrickx
Superconductivity
Uniaxial Compression-Induced Anisotropy and Electronic Dimensionality in the Iron-Based Superconductor FeSe
Alexy Bertrand, Masaki Mito, Kazuma Nakamura et al. (+1 more)
The
evolution of the superconducting transition temperature ($T_c$) in FeSe was investigated under in-plane, out-of-plane, and hydrostatic compression. For pressures up to 0.6 GPa, $T_c$ increases regardless of the compression mode, consistent with the suppression of nematic ordering. However, once nematicity is suppressed, $T_c$ exhibits a striking directional dependence: out-of-plane compression shows behavior similar to the hydrostatic case, with a sharp increase in $T_c$, whereas in-plane compression suppresses superconductivity. First-principles calculations suggest that in-plane compression shifts a hybridized band of Se $p_z$ and Fe $d_{x^2-y^2}$ character so that it crosses the
Fermi level along the $\Gamma$-Z direction, leading to the emergence of an additional metallic band. This leads to an increased three-dimensionality of the electronic structure and may be interpreted as a possible Lifshitz-type change in the
Fermi surface.
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All authors Alexy Bertrand, Masaki Mito, Kazuma Nakamura, Mahmoud Abdel-Hafiez
Soft Condensed Matter
Phase separation by polar active transport
Sudipta Pattanayak, Alfredo Sciortino, Laurent Blanchoin et al. (+2 more)
We propose an active Cahn-Hilliard theory for the dynamics of a new type of phase transition where the driving force is not the direct interactions between the two separating components, but their active sorting by a third polar species. This third species can transport the other two along its polarity in opposite directions, thus separating them. Inspired by recent experiments where molecular motors that walk in opposite directions along microtubules are sorted into separated domains, our theoretical description of this process introduces a new mechanism for active phase separation and could serve as a model for the organization of biological material in space inside
cells. We predict the formation of motor domains, and further show that they can either coarsen to form macroscopic phases or reach a finite micro- or mesoscopic steady state size, these latter due to an arrest of coarsening through activity.
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All authors Sudipta Pattanayak, Alfredo Sciortino, Laurent Blanchoin, Manuel Théry, Jean-Francois Joanny
Superconductivity
Detecting pairing symmetry of bilayer nickelates using electronic Raman scattering
Jun Zhan, Matías Bejas, Andreas P. Schnyder et al. (+3 more)
The recent discovery of high-temperature superconductivity in both bulk and thin-film
bilayer nickelates La$_3$Ni$_2$O$_7$ has garnered significant
attention. However, the corresponding pairing
symmetry remains debated in both experiments and theoretical studies due to conflicting experimental evidence from bulk and thin-film materials. In this work, we examine the electronic Raman response across different channels for various pairing
symmetries within a two-orbital
bilayer model. By comparing Raman susceptibilities obtained from multiorbital and band-additive approaches, we demonstrate that Raman response can distinguish between different pairing
symmetries and identify pocket-dependent gap amplitudes for both fully gapped and nodal superconducting states. Specifically, the nodal $d_{x^2-y^2}/d_{xy}$-wave pairing exhibits robust low-energy power-law behavior, distinct from a fully gapped pairing. Additionally, for the $s_{\pm}$-wave pairing, the detailed gap anisotropy on the $\beta$ pocket can be determined. Possible experimental implications are also discussed. Our results highlight the crucial role of multiorbital effects in shaping the Raman spectra and establish electronic Raman scattering as a powerful and
symmetry-resolved probe for determining the superconducting gap in unconventional
superconductors.
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All authors Jun Zhan, Matías Bejas, Andreas P. Schnyder, Andrés Greco, Xianxin Wu, Jiangping Hu
Materials Science
Parameter-Efficient Fine-Tuning of Machine-Learning Interatomic Potentials for Phonon and Thermal Properties
Jonas Grandel, Philipp Benner and Janine George
Machine-learning interatomic potentials are widely used as computationally efficient surrogates for density functional theory in atomistic simulations, enabling large-scale, long-time modeling of materials systems. We investigate how different fine-tuning strategies influence the prediction of harmonic
phonon band structures, thermal properties, and the potential energy surface along imaginary
phonon modes. We achieve substantial accuracy improvements with minimal additional data, with as few as 10 additional training structures already yielding significant gains. In addition to existing approaches, we introduce Equitrain, a finetuning framework that implements LoRA-based adaptation. Across 53 materials systems, we show that fine-tuned models consistently outperform both the underlying pretrained model and models trained from scratch. Equitrain achieves the best overall performance, and our results demonstrate that fine-tuning enables accurate
phonon predictions.
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Strongly Correlated Electrons · Cross-listed from math-ph
Toral Chern-Simons TQFT via Geometric Quantization in Real Polarization
Daniel Galviz
We construct toral Chern-Simons theory with gauge group $\mathbb T=\mathfrak t/\Lambda\cong U(1)^n$ from an even, integral, nondegenerate symmetric bilinear form $K:\Lambda\times\Lambda\to\mathbb Z$ by
geometric quantization via real polarization. We obtain a
unitary extended $(2+1)$-dimensional TQFT by constructing the boundary state spaces and canonical operators and proving that they satisfy the cylinder and gluing axioms. The finite discriminant group $G_K=\Lambda^*/K\Lambda$ arises naturally in the theory and controls the genus-$g$ state spaces. At genus one, the theory recovers the finite quadratic data underlying bosonic Abelian topological order.
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Materials Science
Observation of acoustic magneto-chiral anisotropy in $\alpha$-quartz
M. Altangerel, S. Badoux, C. Proust et al. (+2 more)
We report the experimental observation of magneto-
chiral anisotropy in the longitudinal and transverse ultrasound propagation in $\alpha$-quartz. To perform such measurement, we have built an ultrasound spectrometer with unprecedented experimental resolution of the order of $\Delta v/v \sim 10^{-8}$. We present a simple macroscopic Becquerel-like analytical model that accounts for the magnitude of the observed effect and its frequency dependence.
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All authors M. Altangerel, S. Badoux, C. Proust, D. Vignolles, G. L. J. A. Rikken