arXiv subjects

Bartosz Krajewski

Publications and source records attributed to Bartosz Krajewski.

3 recordsLinked to original sources

arXiv2024

Dependence of the charge transport in tilted chains on the choice of two-body interaction

We study tilted chains of spinless fermions in the presence of the nearest-neighbor density-density interaction for which the noninteracting counterpart displays Stark localization. We demonstrate that the latter two-body interaction can be decomposed into two (orthogonal) parts which, respectively, commute and do not commute with the single-particle Hamiltonian. We derive an explicit form of the noncommuting part that decreases with tilt and describes the nearest-neighbor correlated hopping and the pair-hopping interaction. When the density-density coupling is replaced by the pair-hopping interaction of the same magnitude then the charge dynamics may be faster by a few orders of magnitude than in the original model.

cond-mat.str-el↗

arXiv2023

Modelling sample-to-sample fluctuations of the gap ratio in finite disordered spin chains

We study sample-to-sample fluctuations of the gap ratio in the energy spectra in finite disordered spin chains. The chains are described by the random-field Ising model and the Heisenberg model. We show that away from the ergodic/nonergodic crossover, the fluctuations are correctly captured by the Rosenzweig-Porter (RP) model. However, fluctuations in the microscopic models significantly exceed those in the RP model in the vicinity of the crossover. We show that upon introducing an extension to the RP model, one correctly reproduces the fluctuations in all regimes, i.e., in the ergodic and nonergodic regimes as well as at the crossover between them. Finally, we demonstrate how to reduce the sample-to-sample fluctuations in both studied microscopic models.

cond-mat.stat-mech↗

arXiv2021

Phenomenology of spectral functions in disordered spin chains at infinite temperature

Studies of disordered spin chains have recently experienced a renewed interest, inspired by the question to which extent the exact numerical calculations comply with the existence of a many-body localization phase transition. For the paradigmatic random field Heisenberg spin chains, many intriguing features were observed when the disorder is considerable compared to the spin interaction strength. Here, we introduce a phenomenological theory that may explain some of those features. The theory is based on the proximity to the noninteracting limit, in which the system is an Anderson insulator. Taking the spin imbalance as an exemplary observable, we demonstrate that the proximity to the local integrals of motion of the Anderson insulator determines the dynamics of the observable at infinite temperature. In finite interacting systems our theory quantitatively describes its integrated spectral function for a wide range of disorders.

cond-mat.dis-nn↗