Materials Science · Cross-listed from physics.app-ph
Impact of Switching Layer Architecture on Power Consumption in RRAM
John F. Hardy II, Jack A. Garrard, Guilherme S.Y. Giardini et al. (+1 more)
This work demonstrates that porous helical WOx architectures enable a distinct low-power regime for planar ITO/WOx/ITO resistive random-access devices. While thin film and helical devices behave similarly at a 5 mA compliance, only helical devices sustain reproducible operation at 500 uA, where RESET voltages reduce by ~60%, switching currents decrease by 68-75%, and SET/RESET power drops by ~89% and ~83%. With helical devices operating at 500 uA, the
memory window expands 400-600% due to selective suppression of high-resistive-state leakage, yielding both lower-power and improved read margin in a regime inaccessible to thin film devices. These results highlight geometry-driven field enhancement and confinement as practical design principles for low-power, high-margin resistive
memories and point toward opportunities in transparent, flexible, and high-surface-area material systems.
Read the full abstract ▾
All authors John F. Hardy II, Jack A. Garrard, Guilherme S.Y. Giardini, Carlo R. daCunha
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Frequency multiplication in Terahertz band using AlGaN/GaN plasmonic crystals
Michael Shur and Gregory Aizin
The
plasma oscillations in high-mobility field-effect transistors (HEMTs) have emerged as a key physical mechanism for manipulating electromagnetic radiation in the sub-terahertz (sub-THz) and THz frequency ranges. These collective electron excitations can be excited and tuned electrically offering a compelling route to compact, integrable components for a wide range of next-generation technologies, including sixth-generation (6G) wireless networks, high-resolution biomedical and chemical spectroscopy, industrial process monitoring, and advanced security and defense systems. For these applications, plasmonic
crystals – periodic arrays of many strongly coupled FET channels – are particularly promising. In this work, we report on a new class of collective excitations in plasmonic
crystals termed rotonic plasmons, which arise at plasmonic mode crossings and exhibit a
parabolic dispersion law reminiscent of soft-mode and roton-like spectra. We show that uniform gate modulation across plasmonic
crystal unit
cells induces periodic variations in the sheet carrier concentration and, consequently, in the
plasma frequency. This time-periodic modulation drives nonlinear plasmonic parametric resonances enabling RF-to-THz conversion. By solving the generalized Mathieu equation with damping, we demonstrate that high-amplitude gate pumping enables frequency multiplication and, at cryogenic temperatures (77K) leads to parametric instabilities due to enhanced electron mobility. In plasmonic
crystals with lower mobility, RF-to-THz conversion can instead be realized via periodic short-pulse excitation, a regime we introduce as Time-Domain Frequency Multiplication (TDFM). Investigation of AlGaN/GaN low-high plasmonic
crystals confirm their potential as tunable, compact THz sources.
Read the full abstract ▾
Materials Science
Incorporating Si into Sb2Se3: Tailoring Optical Phase Change Materials via Nanocomposites
Chih-Yu Lee, Yi-Siou Huang, Felix Adams et al. (+10 more)
Chalcogenide-based optical phase change materials (OPCMs) exhibit a large contrast in refractive index when reversibly switched between their stable amorphous and crystalline states. OPCMs have rapidly gained
attention due to their versatility as nonvolatile amplitude or phase modulators in various photonic devices. However, open challenges remain, such as achieving reliable response and transparency spanning into the visible spectrum, a combination of properties in which current broadband OPCMs (e.g., Ge2Sb2Se4Te1, Sb2Se3, or Sb2S3) fall short. Discovering novel materials or engineering existing ones is, therefore, crucial in extending the application scope of OPCMs. Here, we use magnetron co-sputtering to study the effects of Si doping into Sb2Se3. We employ ellipsometry, X-ray diffraction, Raman spectroscopy, and scanning and transmission electron microscopy to investigate the effects of Si doping on the optical properties and
crystal structure and compare these results with those from first principles calculations. Moreover, we study the crystallization and melt-quenching of thin films via nano-differential scanning calorimetry (NanoDSC). Our experiments demonstrate that 20% Si doping increases the transparency window in both states, specifically to 800 nm (1.55 eV) in the amorphous phase, while reducing power consumption by lowering the melting temperature. However, this reduction comes at the cost of reducing the refractive index contrast between states and slowing the kinetics of the phase transition.
Read the full abstract ▾
All authors Chih-Yu Lee, Yi-Siou Huang, Felix Adams, Chuanyu Lian, Hongyi Sun, Jie Zhao, Zichao Ye, Nathan Youngblood, Juejun Hu, Leslie H Allen, Yifei Mo, Ichiro Takeuchi, Carlos A Rios Ocampo
Materials Science · Cross-listed from cs.LG
High Cycle S-N curve prediction for Al 7075-T6 alloy using Recurrent Neural Networks (RNNs)
Aryan Patel
Aluminum is a widely used
alloy, which is susceptible to fatigue failure. Characterizing fatigue performance for materials is extremely time and cost demanding, especially for high cycle data. To help mitigate this, a transfer learning based framework has been developed using Long short-term
memory networks (LSTMs) in which a source LSTM model is trained based on pure axial fatigue data for Aluminum 7075-T6
alloy which is then transferred to predict high cycle torsional S-N curves. The framework was able to accurately predict Al torsional S-N curves for a much higher cycle range. It is the belief that this framework will help to drastically mitigate the cost of gathering fatigue characteristics for different materials and help prioritize tests with better cost and time constraints.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Electron-beam-induced Contactless Manipulation of Interlayer Twist in van der Waals Heterostructures
Nicola Curreli, Tero S. Kulmala, Riya Sebait et al. (+6 more)
The ability to dynamically control the relative orientation of layers in two dimensional (2D) van der Waals (vdW)
heterostructures represents a critical step toward the realization of reconfigurable nanoscale devices. Existing actuation methods often rely on mechanical contact, complex architectures, or extreme operating conditions, which limit their applicability and scalability. In this work, we present a proof-of-concept demonstration of contactless electrostatic actuation based on electron-beam-induced charge injection. By locally charging an insulating hexagonal boron nitride (hBN) flake on an electrically grounded
graphene layer, we create an interfacial electric field that generates in-plane electrostatic torque and induces angular displacement. We validate the induced rotation through in-situ scanning electron microscopy (SEM) and twist-dependent Raman spectroscopy.
Read the full abstract ▾
All authors Nicola Curreli, Tero S. Kulmala, Riya Sebait, Nicolò Petrini, Matteo Bruno Lodi, Roman Furrer, Alessandro Fanti, Michel Calame, Ilka Kriegel
Materials Science · Cross-listed from physics.chem-ph
Assessing the impact of contact time on leachate chemistry from recycled concrete aggregates
Morgan D. Sanger, Gabrielle Campagnola, Robin Ritchey et al. (+2 more)
Recycled concrete aggregate (RCA) is recognized as a readily available, mechanically sufficient construction and demolition waste product that is suitable as a base course substitute for natural, virgin aggregate in pavement construction. Environmentally responsible applications of RCA must consider the high alkalinity, high pH leachate, and heavy metal leaching risks reported in the literature. The existing body of literature does not address discrepancies between field and laboratory measurements of RCA leachate pH, nor are there any existing studies of aged RCA leachate composition as a function of time. To consider the influence of contact time on RCA leachate, the present study evaluates recovered RCA base course samples from the Minnesota Road Research highway construction study site using modified batch test methodology. Leachate pH, alkalinity, and calcium ion (Ca2+) concentration were monitored for 24 hours to understand RCA leachate chemistry during the initial contact period. Leachate pH is high upon initial contact with water (pH > 10) and decreases over time as it reacts with atmospheric carbon dioxide. Calcium ion concentration increases rapidly in the initial contact period, then more gradually as calcium saturation is reached. Alkalinity stabilizes (50-65 mg CaCO3/L) after a dramatic increase during the initial contact period.
Read the full abstract ▾
All authors Morgan D. Sanger, Gabrielle Campagnola, Robin Ritchey, Tuncer B. Edil, Matthew Ginder-Vogel
Statistical Mechanics · Cross-listed from physics.soc-ph
From motifs to Lévy flights: Modeling urban mobility in Bogotá's public transport system
Juan F. Alayón-Martínez and Alejandro P. Riascos
In this paper, we study two years of access card validation records from Bogotá's
multimodal public transport system, comprising over 2.3 billion trips across bus rapid transit, feeder buses, dual-service buses, and an aerial cable network. From user trajectories constructed exclusively from access records, we derive motifs that reveal recurrent mobility patterns extending beyond simple two-location visits. This approach enables the construction of an integrated origin-destination (OD)
matrix covering 2,828 urban zones. Similarity analysis using the Jensen-Shannon divergence confirms the temporal stability of mobility structures across semesters, despite infrastructure changes and fare policy adjustments. From the obtained OD
matrices, we derive transition probabilities between zones and uncover a robust power-law relationship with geographical distance, consistent with Lévy flight dynamics. We validate our model using Monte Carlo simulations showing that reproduces both local and long-range displacements, with similar scaling exponents across time. These findings demonstrate that Bogotá's public transport mobility can be effectively modeled through Lévy processes, providing a novel framework for analyzing complex transportation systems based solely on user access records.
Read the full abstract ▾
Materials Science
Improper-proper ferroelectric competition as a mechanism for multistate polarisation and ferrielectric-like behaviour
Cameron A.M Scott, Finlay D. Morrison and Nicholas. C. Bristowe
In this paper, we re-explore a simple textbook Landau model describing improper ferroelectricity and show that in the limit where both proper and improper instabilities exist and compete, improper ferroelectrics can display switching between multiple polarisation states. Using first principles calculations we highlight how the hexagonal tungsten bronze materials may be an archetypal case, with the possibility to switch between improper and proper phases. The resulting functional characteristics are akin to "ferrielectrics", with switching behaviour in the form of a triple hysteresis loop. Such functionality could be ideal for creating non-volatile multistate systems for use in
memory devices or as a backbone for neuromorphic computing.
Read the full abstract ▾
Strongly Correlated Electrons
Spin-dependent orbital selectivity and partial Kondo-screening in magnetically ordered Hund's metal
Shivani Bhardwaj and Sudhir K. Pandey
Hund's
metallicity in 3$d$ transition metal
oxides constitutes a rare class of compounds, since they have been long understood considering the dominance of Hubbard $U$. $\mathrm{LiV_2O_4}$& $\mathrm{Sr_2CoO_4}$ belong to this rare class of metals; among them, $\mathrm{LiV_2O_4}$ has been the subject of extensive investigations for its unconventional heavy-
fermion behavior, while studies on $\mathrm{Sr_2CoO_4}$ remain limited despite its anomalous
ferromagnetic ground state. In this study, we report an unusual
spin-orbital selective localization in $\mathrm{Sr_2CoO_4}$ leading to a sharp Kondo resonance at $\sim$70 K in the
spin-$up$ channel of orbitals of $t_{2g}$
symmetry using a combination of Density functional theory and Dynamical mean field theory (DFT+DMFT) calculations. Correspondingly, an appreciable reduction in the magnetization below $T$=100 K further suggests partial Kondo screening of local moments active at low temperatures, explaining its effective
spin magnetization state and upturn in its resistivity observed in experimental reports. We note a significant effect of Hund's induced
spin-orbital selective incoherence in dictating the temperature
evolution of its macroscopic observables e.g.
spin-
spin correlation function and effective local moment. Our results reveal a potentially distinct/new form of
spin-dependent selectivity induced via Hund's coupling in addition to the conventional orbital-selectivity in the Hund's metals, as a plausible key mechanism in stabilizing their long-range
magnetic order.
Read the full abstract ▾
Materials Science
The line bundle regime and the scale-dependence of continuum dislocation dynamics
Joseph Pierre Anderson and Anter El-Azab
Continuum dislocation dynamics (CDD) has become the state-of-the-art theoretical approach for mesoscale dislocation plasticity of metals. Within this approach, there are multiple CDD theories that can all be derived from the principles of statistical mechanics. In these theories density-based measures are used to represent dislocation lines. Establishing these density measures requires some level of coarse graining with the result of losing track of some parts of the dislocation population due to cancellation in the tangent vectors of unaligned dislocations. The leading CDD theories either treat dislocations as nearly parallel or distributed locally over orientation space. The difference between these theories is a matter of the spatial resolution at which the definition of the relevant dislocation density field holds: for fine resolutions, single dislocations are resolved and there is no cancellation; for coarse resolutions, whole dislocation loops could contribute at a single point and there is complete cancellation. In the current work, a formulation of the resolution-dependent transition between these limits is presented in terms of the statistics of dislocation line orientation fluctuations about a local average line direction. From this formulation, a study of the orientation fluctuation behavior in intermediate resolution regimes is conducted. Two possible closure equations for truncating the moment sequence of the fluctuation distributions relating the two theories mentioned above are evaluated from data, the newly introduced line bundle closure and the previous standard maximum
entropy closure relations. The line bundle closure relation is shown to be accurate for coarse-graining lengths up to half the dislocation spacing and the maximum
entropy closure is found to poorly agree with the data at all coarse-graining lengths.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
A Physical Unclonable Function Based on Variations of Write Times in STT-MRAM due to Manufacturing Defects
Jacob Huber and Supriyo Bandyopadhyay
A physical unclonable function (PUF) utilizes the unclonable random variations in a device's responses to a set of inputs to produce a unique "biometric" that can be used for authentication. The variations are caused by unpredictable, unclonable and random manufacturing defects. Here, we show that the switching time of a
magnetic tunnel junction injected with a
spin-polarized current generating
spin transfer torque is sensitive to the nature of structural defects introduced during manufacturing and hence can be the basis of a PUF. We use micromagnetic simulations to study the switching times under a constant current excitation for six different (commonly encountered) defect morphologies in
spin-transfer-torque
magnetic random access
memory (STT-MRAM) to establish the viability of a PUF.
Read the full abstract ▾
Soft Condensed Matter
Neural-Network-Assisted Boltzmann Approach for Dilute Microswimmer Suspensions
Haruki Hayano, Akira Furukawa and Kang Kim
We introduce a neural-network-assisted Boltzmann framework that learns the binary-collision map of microswimmers directly from data and uses it to evaluate collision integrals efficiently. Using a representative model swimmer, the learned map quantitatively predicts translational and rotational diffusivities and enables a linear-stability analysis of isotropy against polar ordering in dilute suspensions. The resulting predictions closely match direct simulations. The present framework is agnostic to active matter models and broadly applicable: once two-body collision data are obtained – either from simulations or experiments – the same surrogate can be used to evaluate kinetic transport across dilute conditions where binary collisions dominate. Because the workflow relies only on pre- and post-collision statistics, the present approach provides a general data-driven route linking particle-scale interactions to macroscopic transport and collective behavior in active suspensions.
Read the full abstract ▾
Superconductivity
Finite-size and quenching effects on hyperuniform structures formed during cooling
A. Cruz-García, J. Puig, R. M. Besana et al. (+2 more)
The outstanding physical properties of hyperuniform condensed matter systems holds significant promise for technological applications and studying effects that may disrupt this hidden order is therefore very important.
Vortex matter in
superconductors is a model system to study this problem since imaging experiments have revealed that correlated disorder in the host media and finite size effects disrupt the hyperuniformity of the in-plane arrangement of
vortices. Here we report simulations of layered interacting elastic lines as a model for the
vortex lattice in three-dimensional
superconductors, following a cooling protocol that closely mimics the experimental conditions. We show that finite-thickness effects limiting the hyperuniformity range arise both in
equilibrium and out-of-
equilibrium. Our results provide a theoretical framework to draw a realistic road-map on synthesizing hyperuniform materials when cooling structures on finite host media with disorder.
Read the full abstract ▾
All authors A. Cruz-García, J. Puig, R. M. Besana, A. B. Kolton, Y. Fasano
Materials Science · Cross-listed from quant-ph
Quantum simulation of carbon capture in periodic metal-organic frameworks
Dario Rocca, Jerome F. Gonthier, Joshua Levin et al. (+4 more)
Carbon capture is vital for decarbonizing heavy industries such as steel and chemicals. Metal-organic frameworks (MOFs), with their high surface area and structural tunability, are promising materials for CO2 capture. This study focuses on Fe-MOF-74, a
magnetic Mott
insulator with exposed metal sites that enhance CO2 adsorption. Its strongly correlated electronic structure challenges standard DFT methods, which often yield inconsistent predictions. We initially
benchmark adsorption energies using various DFT functionals, revealing substantial variability and underscoring the need for more accurate approaches, such as those provided by
quantum computing. However, practical
quantum algorithms are far less established for simulations of periodic materials, particularly when the plane-wave basis set, often comprising tens of thousands of basis vectors, is used. To address this, we employ an active space reduction strategy based on Wannier functions and natural orbital selection. Localized orbitals around the adsorption site are identified, and MP2 natural orbitals are used to improve convergence of correlation energies. Adsorption energies are then computed using a
quantum number-preserving ansatz within the variational
quantum eigensolver framework. In addition to classical simulations, we conduct
quantum experiments using the sample-based
quantum diagonalization method. Although current hardware limits the size of feasible simulations, our approach offers a more efficient and scalable path forward. These results advance the applicability of
quantum algorithms to realistic models of carbon capture and periodic materials more broadly.
Read the full abstract ▾
All authors Dario Rocca, Jerome F. Gonthier, Joshua Levin, Tobias Schafer, Andreas Gruneis, Byeol Kang, Hong Woo Lee
Disordered Systems and Neural Networks · Cross-listed from physics.bio-ph
Mean-field analysis of a neural network with stochastic STDP
Pascal Helson, Etienne Tanré and Romain Veltz
Analysing biological spiking neural network models with synaptic plasticity has proven to be challenging both theoretically and numerically. In a network with N all-to-all connected
neurons, the number of synaptic connections is on the order of $N^2$, making these models computationally demanding. Furthermore, the intricate coupling between
neuron and synapse dynamics, along with the heterogeneity generated by plasticity, hinder the use of classic theoretical tools such as mean-field or slow-fast analyses. To address these challenges, we introduce a new variable which we term a typical
neuron X. Viewed as a post-synaptic
neuron, X is composed of the activity state V , the time since its last spike S, and the empirical distribution $\xi$ of the triplet V , S and W (incoming weight) associated to the pre-synaptic
neurons. In particular, we study a
stochastic spike-timing-dependent plasticity (STDP) model of connection in a probabilistic Wilson-Cowan spiking neural network model, which features binary neural activity. Taking the large N limit, we obtain from the empirical distribution of the typical
neuron a simplified yet accurate representation of the original spiking network. This mean-field limit is a piecewise deterministic Markov process (PDMP) of McKean-Vlasov type, where the typical
neuron dynamics depends on its own distribution. We term this analysis McKean-Vlasov mean-field (MKV-MF). Our approach not only reduces computational complexity but also provides insights into the dynamics of this spiking neural network with plasticity. The model obtained is mathematically exact and capable of tracking transient changes. This analysis marks the first exploration of MKV-MF dynamics in a network of spiking
neurons interacting with STDP.
Read the full abstract ▾
Materials Science
Active-Learning Inspired $\textit{Ab Initio}$ Theory-Experiment Loop Approach for Management of Material Defects: Application to Superconducting Qubits
Sarvesh Chaudhari, Cristóbal Méndez, Rushil Choudhary et al. (+11 more)
Surface
oxides are associated with two-level systems (TLSs) that degrade the performance of niobium-based superconducting
quantum computing devices. To address this, we introduce a predictive framework for selecting metal capping layers that inhibit niobium
oxide formation. Using DFT-calculated oxygen interstitial and vacancy energies as thermodynamic descriptors, we train a logistic regression model on a limited set of experimental outcomes to successfully predict the likelihood of
oxide formation beneath different capping materials. This approach identifies Zr, Hf, and Ta as effective
diffusion barriers. Our analysis further reveals that the
oxide formation energy per oxygen atom serves as an excellent standalone descriptor for predicting barrier performance. By combining this new descriptor with
lattice mismatch as a secondary criterion to promote structurally coherent interfaces, we identify Zr, Ta, and Sc as especially promising candidates. This closed-loop strategy integrates first-principles theory, machine learning, and limited experimental data to enable rational design of next-generation materials.
Read the full abstract ▾
All authors Sarvesh Chaudhari, Cristóbal Méndez, Rushil Choudhary, Tathagata Banerjee, Maciej W. Olszewski, Jadrien T. Paustian, Jaehong Choi, Zhaslan Baraissov, Raul Hernandez, David A. Muller, B. L. T. Plourde, Gregory D. Fuchs, Valla Fatemi, Tomás A. Arias
Materials Science
Epitaxially-stabilized growth of wüstite FeO on 4H-SiC
Faisal Kimbugwe, Marzieh Baan, Alexandra Fonseca Montenegro et al. (+2 more)
Iron(II) monoxide (FeO) is thermodynamically stable in the halite (wüstite) structure only at elevated temperatures in a typically non-stoichiometric, Fe-deficient, Fe$_{1-z}$O form that tends to phase separate and/or transform into metallic $\alpha$-Fe and magnetite Fe$_3$O$_4$ at ambient conditions. Here we report on the successful growth of up to 180 nm thick $(111)$-oriented FeO heteroepitaxial films on slightly
lattice-matched 4H-SiC$(0001)$ using molecular beam epitaxy (MBE). The films have flat, terraced surfaces with tall multi-layer steps. X-ray diffraction (XRD), high-resolution scanning transmission electron microscopy (S/TEM), energy-dispersive X-ray spectroscopy (EDS), and core-level electron energy loss spectroscopy (EELS) collectively confirm the epilayer as phase-pure wüstite FeO, with atomically sharp FeO/SiC interfaces. The films are found to exhibit a slight misfit strain-induced rhombohedral distortion that does not appear to vary over the range of thicknesses examined. These results demonstrate the power of epitaxial stabilization for integrating a thermodynamically unstable, yet functionally interesting material with a commercially available and technologically important
semiconductor platform.
Read the full abstract ▾
All authors Faisal Kimbugwe, Marzieh Baan, Alexandra Fonseca Montenegro, Roberto C Myers, Tyler J Grassman
Mesoscale and Nanoscale Physics
Symmetry in magnetoelectric electromagnetism and magnetoelectric meta-atoms
E. O. Kamenetskii
While in electromagnetism we have space-time
symmetry, magnetoelectric (ME) processes are characterized by space-time
symmetry breaking. Our goal is to show that
quantum vacuum fields with both time reversal and space inversion
symmetry breaking (so-called ME fields) can be observed in subwavelength regions of electromagnetic (EM) radiation. The sources of ME fields are ME meta-atoms, subwavelength elements made of
magnetic insulators, where the dynamical ME behavior is due to modulations and topological coupling of magnetization and electric polarization. The interaction between EM and ME systems occurs through virtual structures, ME virtual
photons. Experimentally, ME
quantum vacuum states can be detected in a microwave cavity. The topic of these studies concerns fundamental aspects of ME
quantum electrodynamics (MEQED).
Read the full abstract ▾
Superconductivity
Vestigial pairing from fluctuating magnetism and triplet superconductivity
Yanek Verghis, Denis Sedov, Jakob Weßling et al. (+2 more)
We study the finite-temperature vestigial superconducting phases of a two-dimensional system of fluctuating
spin-triplet pairing and
spin magnetism. Denoting the respective primary order parameters by $\mathbf{d}$ and $\mathbf{N}$, which are not long-range ordered at finite temperature, the composite fields $\phi_{dd} = \mathbf{d}\cdot\mathbf{d}$ and $\phi_{dN} = \mathbf{d}\cdot\mathbf{N}$ are
spin-rotation invariant and can condense at finite temperature. Using a large-$N$ approach that respects the Mermin-Wagner
theorem, we here derive the phase diagram which features two vestigial
superconductors: $(A)$ a charge-$4e$
superconductor with $\phi_{dd}\neq 0$ and $\phi_{dN} =0$ and $(B)$ a charge-$2e$ state with $\phi_{dN} ,\phi_{dd}\neq 0$. We analyze the temperature and coupling-constant dependent properties of these two
superconductors using a perturbative approach and a variational Hartree-Fock study. This reveals non-trivial spectra in the
superconductors, which result from the fundamental building blocks being distinct from the usual Cooper pairs–in phase $(A)$, the elementary
bosons are bound states of four electrons and, in phase $(B)$, of three electrons and a hole. This work complements the previous study [Nat. Commun. 15, 1713 (2024), arXiv:2301.01344], which focused on the properties of phase $(B)$.
Read the full abstract ▾
All authors Yanek Verghis, Denis Sedov, Jakob Weßling, Prathyush P. Poduval, Mathias S. Scheurer
Statistical Mechanics · Cross-listed from quant-ph
Computational access to lattice and long-wavelength physics in quantum mutual information
Patrick M. Lenggenhager, M. Michael Denner, Doruk Efe Gökmen et al. (+3 more)
Quantum mutual information is an important tool for characterizing correlations in
quantum many-body systems, but its numerical evaluation is often prohibitively expensive. While some variants of Rényi Mutual Information (RMI) are computationally more tractable, it is not clear whether they correctly capture the long-wavelength physics or are dominated by UV effects, which is of key importance in
lattice simulations. We analyze the relevance of
lattice effects on the family of $\alpha$-$z$ Rényi mutual informations for ground states of models with conformal field theory descriptions. On the example of massless free
fermions we identify distinct regions in the $\alpha$-$z$ plane, where RMI corrections due to the
lattice are relevant or irrelevant. We further support these findings with MPS calculations on the transverse field Ising model (TFIM). Our results, accompanied by the open-source Julia package QMICalc$.$jl, provide guidance to using RMI in
quantum-many body physics numerical computations.
Read the full abstract ▾
All authors Patrick M. Lenggenhager, M. Michael Denner, Doruk Efe Gökmen, Maciej Koch-Janusz, Titus Neupert, Mark H. Fischer
Soft Condensed Matter
Turbulent Dynamics in Active Solids
Wilhelm Sunde Lie, Ingve Simonsen and Paul Gunnar Dommersnes
Turbulence is most commonly associated with high Reynolds number flow, however the framework of turbulent dynamics has been conceptually extended to many other fields, such as magnetohydrodynamic
turbulence, elastic wave
turbulence in solids, and more recently to low Reynolds number active
turbulence in biological fluids. Here we report a form of solid turbulent dynamics in a self-propelled two-dimensional elastic sheet. We show numerically that the polar ordering dynamics in the active elastic solid model (AES) exhibit hallmark features of turbulent dynamics: power-law scaling of the energy spectrum and non-Gaussian statistics of velocity increments. However, there is no energy cascade, in line with previous findings for active
turbulence in fluids. These results extend the concept of active
turbulence to solid-state active matter, and can be important for understanding collective dynamics in biological active solids such as bacterial colonies and epithelial
cell layers.
Read the full abstract ▾
Strongly Correlated Electrons
Detecting quantum spin liquid on Kitaev model through a superconducting junction
A. R. Moura and L. V. Santos
The Kitaev model belongs to an unconventional class of two-dimensional
spin systems characterized by anisotropic, bond-dependent interactions that give rise to
Quantum Spin Liquid (QSL) states. These exotic phases, marked by the absence of
magnetic ordering even at zero temperature, support fractionalized excitations and emergent gauge fields. A particularly compelling feature of the Kitaev model is its exact solvability, which reveals low-energy excitations in the form of itinerant Majorana
fermions-quasiparticles that obey non-Abelian statistics and are of central interest in topological
quantum computation due to their inherent robustness against local perturbations and decoherence. Despite extensive theoretical advancements, the experimental identification of QSLs remains challenging, as conventional
magnetic probes fail to detect their defining properties. In this work, we present a theoretical investigation of
spin current injection from a superconducting metal into a Kitaev
quantum spin liquid. By employing a spintronic framework, we derive the dynamics of the injected
spin current and demonstrate how its signatures can be traced back to the underlying Majorana excitations in the
spin liquid phase. Superconductivity plays a pivotal role in this context, not only as a source of coherent quasiparticles but also as a platform with potential for interfacing with topological
quantum devices. Our analysis contrasts the Kitaev-
superconductor interface with conventional
ferromagnetic junctions, where
spin transport is carried by
magnons, and highlights distinctive features in the
spin current response. These findings open new directions for the detection of QSLs and contribute to the broader effort of integrating topological
quantum materials into scalable
quantum technologies.
Read the full abstract ▾
Statistical Mechanics
One-dimensional long-range Ising model: two (almost) equivalent approximations
Valerio Pagni, Guido Giachetti, Andrea Trombettoni et al. (+1 more)
We investigate the critical behavior of the one-dimensional Ising model with long-range interactions using the functional renormalization group in the local potential approximation (LPA), and compare our findings with Dyson's hierarchical model (DHM). While the DHM lacks translational invariance, it admits a field-theoretical description closely resembling the LPA, up to minor but nontrivial differences. After reviewing the real-space renormalization group approach to the DHM, we demonstrate a remarkable agreement in the critical exponent $\nu$ between the two methods across the entire range of power-law decays $1/2 < \sigma < 1$. We further
benchmark our results against Monte Carlo simulations and analytical expansions near the upper boundary of the nontrivial regime, $\sigma \lesssim 1$.
Read the full abstract ▾
All authors Valerio Pagni, Guido Giachetti, Andrea Trombettoni, Nicolò Defenu