arXiv subjects

Jakub Zakrzewski

Publications and source records attributed to Jakub Zakrzewski.

At least 37 records · Page 2Linked to original sources

arXiv2025

Anderson localization induced by structural disorder

We examine the onset of Anderson localization in three-dimensional systems with structural disorder in the form of lattice irregularities and in the absence of any on-site disordered potential. Analyzing two models with distinct types of lattice regularities, we show that the Anderson localization transition occurs when the strength of the structural disorder is smoothly increased. Performing finite-size scaling analysis of the results, we show that the transition belongs to the same universality class as regular Anderson localization induced by onsite disorder. Our work identifies a new class of structurally disordered lattice models in which destructive interference of matter waves may inhibit transport and lead to a transition between metallic and localized phases.

cond-mat.dis-nn↗

arXiv2025

Self-organized cavity bosons beyond the adiabatic elimination approximation

The long-time behavior of weakly interacting bosons moving in a two-dimensional optical lattice and coupled to a lossy cavity is investigated numerically via the truncated Wigner method, which allows us to take into full account the dynamics of the cavity mode, quantum fluctuations, cavity-boson correlations, and self-organization of individual runs. We first compare our results for small systems with quasi-exact calculations based on quantum trajectories, finding a remarkably good agreement for experimentally relevant boson fillings that improves further with system size. For large systems, we observe metastability at very long times and superfluid quasi-long range order, in sharp contrast with the true long range order found in the ground state of the approximate Bose-Hubbard model with extended interactions, obtained by adiabatically eliminating the cavity field. As the strength of the light-matter coupling increases, the system first becomes supersolid at the Dicke superradiant transition and then turns into a charge-density wave via the Berezinskii-Kosterlitz-Thouless mechanism. The two phase transitions are characterized via an accurate finite-size scaling analysis.

cond-mat.quant-gas↗

arXiv2025

Phenomenology of many-body localization in bond-disordered spin chains

Many-body localization (MBL) hinders the thermalization of quantum many-body systems in the presence of strong disorder. In this work, we study the MBL regime in bond-disordered spin-1/2 XXZ spin chain, finding the multimodal distribution of entanglement entropy in eigenstates, sub-Poissonian level statistics, and revealing a relation between operators and initial states required for examining the breakdown of thermalization in the time evolution of the system. We employ a real space renormalization group scheme to identify these phenomenological features of the MBL regime that extend beyond the standard picture of local integrals of motion relevant for systems with disorder coupled to on-site operators. Our results pave the way for experimental probing of MBL in bond-disordered spin chains.

cond-mat.dis-nn↗

arXiv2025

Many-Body Localization in the Age of Classical Computing

Statistical mechanics provides a framework for describing the physics of large, complex many-body systems using only a few macroscopic parameters to determine the state of the system. For isolated quantum many-body systems, such a description is achieved via the eigenstate thermalization hypothesis (ETH), which links thermalization, ergodicity and quantum chaotic behavior. However, tendency towards thermalization is not observed at finite system sizes and evolution times in a robust many-body localization (MBL) regime found numerically and experimentally in the dynamics of interacting many-body systems at strong disorder. Although the phenomenology of the MBL regime is well-established, the central question remains unanswered: under what conditions does the MBL regime give rise to an MBL phase in which the thermalization does not occur even in the asymptotic limit of infinite system size and evolution time? This review focuses on recent numerical investigations aiming to clarify the status of the MBL phase, and it establishes the critical open questions about the dynamics of disordered many-body systems. Persistent finite size drifts towards ergodicity consistently emerge in spectral properties of disordered many-body systems, excluding naive single-parameter scaling hypothesis and preventing comprehension of the status of the MBL phase. The drifts are related to tendencies towards thermalization and non-vanishing transport observed in the dynamics of many-body systems, even at strong disorder. These phenomena impede understanding of microscopic processes at the ETH-MBL crossover. Nevertheless, the abrupt slowdown of dynamics with increasing disorder strength suggests the proximity of the MBL phase. This review concludes that the questions about thermalization and its failure in disordered many-body systems remain a captivating area open for further explorations.

cond-mat.dis-nn↗

arXiv2025

Gapless deconfined phase in a $\mathbb{Z}_N$ symmetric Hamiltonian created in a cold-atom setup

We investigate a quasi-two-dimensional system consisting of two species of alkali atoms confined in a specific optical lattice potential [Phys. Rev. A 95, 053608 (2017)]. In the low-energy regime, this system is governed by a unique $\mathbb{Z}_N$ gauge theory, where field theory arguments have suggested that it may exhibit two exotic gapless deconfined phases, namely a dipolar liquid phase and a Bose liquid phase, along with two gapped (confined and deconfined) phases. We address these predictions numerically by using large-scale density matrix renormalization group simulations. Our findings provide conclusive evidence for the existence of a gapless Bose liquid phase for $N \geq 7$. We demonstrate that this gapless phase shares the same critical properties as one-dimensional critical phases, resembling weakly coupled chains of Luttinger liquids. In the range of ladder and cylinder geometries and $N$ considered, the gapless dipolar phase predicted theoretically is still elusive and its characterization will probably require a full two-dimensional treatment.

cond-mat.str-el↗

arXiv2025

Nonstabilizerness in U(1) lattice gauge theory

We present a thorough investigation of nonstabilizerness - a fundamental quantum resource that quantifies state complexity within the framework of quantum computing - in a one-dimensional U(1) lattice gauge theory. We show how nonstabilizerness is always extensive with volume, and has no direct relation to the presence of critical points. However, its derivatives typically display discontinuities across the latter: This indicates that nonstabilizerness is strongly sensitive to criticality, but in a manner that is very different from entanglement (that, typically, is maximal at the critical point). Our results indicate that error-corrected simulations of lattice gauge theories close to the continuum limit have similar computational costs to those at finite correlation length and provide rigorous lower bounds for quantum resources of such quantum computations.

quant-ph↗

arXiv2025

Many-body localization crossover is sharper in quasiperiodic spin chains

Due to a phenomenon of many-body localization (MBL), the strong disorder may significantly slow down or even completely hinder the thermalization of quantum many-body systems. A sufficiently deep quasiperiodic potential may also inhibit thermalization. In this work, we numerically demonstrate direct differences in the behavior of standard ergodicity-breaking indicators at the MBL crossover in random and quasiperiodic systems. Our key finding is the exponential increase in the sharpness of the MBL crossover with system size for quasiperiodic systems, a trend that is only linear in disordered systems. The strong tendency towards a non-analytic behavior in quasiperiodic systems is consistent with the existence of dynamical regimes with sharply defined boundaries or an MBL phase transition. It highlights the importance of quasiperiodic systems for our understanding of many-body dynamics.

cond-mat.dis-nn↗

arXiv2024

Design of a Standard-Compliant Real-Time Neural Receiver for 5G NR

We detail the steps required to deploy a multi-user multiple-input multiple-output (MU-MIMO) neural receiver (NRX) in an actual cellular communication system. This raises several exciting research challenges, including the need for real-time inference and compatibility with the 5G NR standard. As the network configuration in a practical setup can change dynamically within milliseconds, we propose an adaptive NRX architecture capable of supporting dynamic modulation and coding scheme (MCS) configurations without the need for any re-training and without additional inference cost. We optimize the latency of the neural network (NN) architecture to achieve inference times of less than 1ms on an NVIDIA A100 GPU using the TensorRT inference library. These latency constraints effectively limit the size of the NN and we quantify the resulting signal-to-noise ratio (SNR) degradation as less than 0.7 dB when compared to a preliminary non-real-time NRX architecture. Finally, we explore the potential for site-specific adaptation of the receiver by investigating the required size of the training dataset and the number of fine-tuning iterations to optimize the NRX for specific radio environments using a ray tracing-based channel model. The resulting NRX is ready for deployment in a real-time 5G NR system and the source code including the TensorRT experiments is available online.

cs.IT↗

arXiv2024

Anomalous localization in spin chains with tilted interactions

Quantum simulators of lattice gauge theories involve dynamics of typically short-ranged interacting particles and dynamical fields. Elimination of the latter via Gauss law leads to infinite range interactions as exemplified by the Schwinger model in a staggered formalism. This motivates the study of long-range interactions, not necessarily diminishing with the distance. Here we consider localization properties of a spin chain with interaction strength growing linearly along the chain as for the Schwinger model. We generalize the problem to models with different interaction ranges. Using exact diagonalization we find the participation ratio of all eigenstates, which allows us to quantify the localization volume in Hilbert space. Surprisingly, the localization volume changes nonmonotonically with the interaction range. Our study is relevant for quantum simulators of lattice gauge theories implemented in state-of-the-art cold atom/ion devices, and it could help to reveal hidden features in disorder-free confinement phenomena in long-range interacting systems.

cond-mat.dis-nn↗

arXiv2024

Recent progress on quantum simulations of non-standard Bose-Hubbard models

In recent years, the systems comprising of bosonic atoms confined to optical lattices at ultra-cold temperatures have demonstrated tremendous potential to unveil novel quantum mechanical effects appearing in lattice boson models with various kinds of interactions. In this progress report, we aim to provide an exposition to recent advancements in quantum simulations of such systems, modeled by different "non-standard" Bose-Hubbard models, focusing primarily on long-range systems with dipole-dipole or cavity-mediated interactions. Through a carefully curated selection of topics, which includes the emergence of quantum criticality beyond Landau paradigm, bond-order wave insulators, the role of interaction-induced tunneling, the influence of transverse confinement on observed phases, or the effect of cavity-mediated all-to-all interactions, we report both theoretical and experimental developments from the last few years. Additionally, we discuss the real-time evolution of systems with long-range interactions, where sufficiently strong interactions render the dynamics non-ergodic. And finally to cap our discussions off, we survey recent experimental achievements in this rapidly evolving field, underscoring its interdisciplinary significance and potential for groundbreaking discoveries.

cond-mat.quant-gas↗

arXiv2024

Many-Body Mobility Edge in Quantum Sun models

The quantum sun model is an interacting model that exhibits sharp signatures of ergodicity breaking phase transition. Here, we show that the model exhibits a many-body mobility edge. We provide analytical arguments for its existence, complemented by the state-of-the-art numerical simulations analysing gap ratios, Thouless times as well as entanglement entropy of eigenstates. We also introduce the quantum sun model with particle number conservation, and we argue that it shares many similarities with his unrestricted predecessor.

cond-mat.dis-nn↗

arXiv2024

Catching thermal avalanches in the disordered XXZ model

We study the XXZ model with a random magnetic field in contact with a weakly disordered spin chain, acting as a finite thermal bath. We revise Fermi's golden rule description of the interaction between the thermal bath and the XXZ spin chain, contrasting it with a nonperturbative quantum avalanche scenario for the thermalization of the system. We employ two-point correlation functions to define the extent $ξ_d$ of the thermalized region next to the bath. Unbounded growth of $ξ_d$ proportional to the logarithm of time or faster is a signature of an avalanche. Such behavior signifies the thermalization of the system, as we confirm numerically for a generic initial state in the ergodic and critical regimes of the XXZ spin chain. In the many-body localized regime, a clear termination of avalanches is observed for specifically prepared initial states and, surprisingly, is not visible for generic initial product states. Additionally, we extract the localization length of the local integrals of motion and show that a bath made out of a weakly disordered XXZ chain has a similar effect on the system as a bath modeled by a Hamiltonian from a Gaussian orthogonal ensemble of random matrices. We also comment on the result of the earlier study (Phys. Rev. B 108, L020201 (2023)), arguing that the observed thermalization is due to external driving of the system and does not occur in the autonomous model. Our work reveals experimentally accessible signatures of quantum avalanches and identifies conditions under which termination of the avalanches may be observed.

cond-mat.dis-nn↗

arXiv2024

Towards the Intuitive Understanding of Quantum World: Sonification of Rabi Oscillations, Wigner functions, and Quantum Simulators

Recently, there has been considerable interest in "sonifying" scientific data; however, sonifying quantum processes using the newest quantum technologies, including Noise Intermediate Scale Quantum devices and quantum random number generators, is still an emerging area of research. Music technologists and composers employ the growing accessibility to diverse data from quantum mechanics as musical tools in the hope of generating new sound expressions. How different is the quantum world from the classical one, and is it possible to express the quantum world using sounds? Quantum phenomena are very different from those that we experience in our everyday lives. Thus, it is challenging to understand them intuitively. In this paper, we propose sonification as a method toward an intuitive understanding of various quantum mechanical phenomena, from Rabi oscillations and resonance fluorescence of a single atom through the generation of Schrödinger cat states in strong laser field physics to insulator-superfluid transition in quantum many-body systems. This paper illustrates various methods we experimented with in sonification and score representations of quantum data depending on the source data and performance settings.

quant-ph↗

arXiv2024

Ground states of one-dimensional dipolar lattice bosons at unit filling

Recent experiments on ultracold dipoles in optical lattices open exciting possibilities for the quantum simulation of extended Hubbard models. When considered in one dimension, these models present at unit filling a particularly interesting ground-state physics, including a symmetry-protected topological phase known as Haldane insulator. We show that the tail of the dipolar interaction beyond nearest-neighbors, which may be tailored by means of the transversal confinement, does not only modify quantitatively the Haldane insulator regime and lead to density waves of larger periods, but results as well in unexpected insulating phases. These insulating phases may be topological or topologically trivial, and are characterized by peculiar correlations of the site occupations. These phases may be realized and observed in state-of-the-art experiments.

cond-mat.quant-gas↗

arXiv2024

The confluence of fractured resonances at points of dynamical, many--body flare

Resonant transport occurs when there is a matching of frequencies across some spatial medium, increasing the efficiency of shuttling particles from one reservoir to another. We demonstrate that in a periodically driven, many--body titled lattice, there are sets of spatially fractured resonances. These ``emanate'' from two essential resonances due to scattering off internal surfaces created when the driving frequency and many--body interaction strength vary, a scattering reminiscent of lens flare. The confluence of these fractured resonances dramatically enhances transport. At one confluence, the interaction strength is finite and the essential resonance arises due to the interplay of interaction with the counter--rotating terms of the periodic drive. We discuss the origin and structure of the fractured resonances, as well as the scaling of the conductance with system parameters. These results furnish a new example of the richness of open, driven, many--body systems.

cond-mat.str-el↗

arXiv2023

Spectral properties of critical 1+1D Abelian-Higgs model

The presence of gauge symmetry in 1+1D is known to be redundant, since it does not imply the existence of dynamical gauge bosons. As a consequence, in the continuum, the Abelian-Higgs model, the theory of bosonic matter interacting with photons, just possesses a single phase, as the higher dimensional Higgs and Coulomb phases are connected via non-perturbative effects. However, recent research published in [Phys. Rev. Lett. 128, 090601 (2022)] has revealed an unexpected phase transition when the system is discretized on the lattice. This transition is described by a conformal field theory with a central charge of $c=3/2$. In this paper, we aim to characterize the two components of this $c=3/2$ theory -- namely the free Majorana fermionic and bosonic parts -- through equilibrium and out-of-equilibrium spectral analyses.

hep-th↗

arXiv2023

Strong-Field Double Ionization in a Three-Electron Atom: Momentum Distribution Analysis

We study strong-field double ionization in a three-electron atom by applying a simplified, reduced-dimensionality model with three active electrons. The influence of the spin-induced symmetry of the spatial part of the wavefunction on the final two-photoectron momentum distribution is discussed. We identify partial momentum distributions originating from different sets of spins of outgoing electrons providing in this way a quantum support connection between V-structure and direct ionization typically explained classically. Changes in the momentum distribution with increasing field amplitude obtained in our simplified model are shown to be well-correlated with experimental data known from the literature. The possible relation between the observed dependencies and different ionization mechanisms is discussed.

physics.atom-ph↗

arXiv2023

Many-body quantum boomerang effect

We study numerically the impact of many-body interactions on the quantum boomerang effect. We consider various cases: weakly interacting bosons, the Tonks-Girardeau gas, and strongly interacting bosons (which may be mapped onto weakly interacting fermions). Numerical simulations are performed using the time-evolving block decimation algorithm, a quasi-exact method based on matrix product states. In the case of weakly interacting bosons, we find a partial destruction of the quantum boomerang effect, in agreement with the earlier mean-field study [Phys. Rev. A \textbf{102}, 013303 (2020)]. For the Tonks-Girardeau gas, we show the presence of the full quantum boomerang effect. For strongly interacting bosons, we observe a partial boomerang effect. We show that the destruction of the quantum boomerang effect is universal and does not depend on the details of the interaction between particles.

cond-mat.dis-nn↗