Probing many-body localization crossover in quasiperiodic Floquet circuits on a quantum processor

TL;DR

This study uses a large-scale quantum processor to experimentally explore the transition between ergodic and many-body localized phases in quasiperiodic Floquet systems, revealing long-time dynamics and localization signatures beyond classical simulation capabilities.

Contribution

First experimental demonstration of many-body localization crossover in large quasiperiodic Floquet systems on a quantum processor, including two-dimensional localization signatures.

Findings

Observed a smooth ergodic-MBL crossover via autocorrelation functions.

Detected logarithmic growth of quantum Fisher information indicating slow entanglement.

Identified localization behavior in both one- and two-dimensional systems.

Abstract

Many-body localization (MBL) provides a mechanism by which interacting quantum systems evade thermalization, leading to persistent memory of initial conditions and slow entanglement growth. Probing these dynamical signatures in large systems and at long evolution times remains challenging for both classical simulations and current quantum devices. Here we experimentally investigate the ergodic-MBL crossover in quasiperiodic Floquet Ising systems using up to 144 qubits on an IBM Quantum processor. By implementing deep Floquet circuits reaching up to 5000 cycles, we access long-time many-body dynamics beyond the regime explored in previous quantum computing experiments. Measurements of autocorrelation functions reveal a smooth crossover from rapid thermalization at weak quasiperiodic potential strength to persistent correlations in the strong-disorder regime. Notably, in addition to the one-dimensional system, we also observe clear signatures consistent with localization behavior in the two-dimensional system. Furthermore, the quantum Fisher information exhibits logarithmic growth over thousands of Floquet cycles, providing evidence for slow entanglement spreading characteristic of the MBL regime. These results demonstrate that programmable quantum processors can serve as experimental platforms for probing nonergodic quantum many-body dynamics and exploring localization phenomena in regimes beyond the reach of classical simulations.