Probing spin hydrodynamics on a superconducting quantum simulator

TL;DR

This paper demonstrates how a superconducting quantum simulator can be used to experimentally study spin transport at infinite temperature, revealing diffusive and subdiffusive behaviors in complex quantum systems.

Contribution

It introduces a scalable method for probing infinite-temperature spin transport using analog quantum circuits on superconducting simulators, including disordered and tilted systems.

Findings

Observed diffusive spin transport in ergodic systems

Detected signatures of anomalous subdiffusion with strong disorder

Demonstrated a scalable approach for studying out-of-equilibrium phenomena

Abstract

Characterizing the nature of hydrodynamical transport properties in quantum dynamics provides valuable insights into the fundamental understanding of exotic non-equilibrium phases of matter. Experimentally simulating infinite-temperature transport on large-scale complex quantum systems is of considerable interest. Here, using a controllable and coherent superconducting quantum simulator, we experimentally realize the analog quantum circuit, which can efficiently prepare the Haar-random states, and probe spin transport at infinite temperature. We observe diffusive spin transport during the unitary evolution of the ladder-type quantum simulator with ergodic dynamics. Moreover, we explore the transport properties of the systems subjected to strong disorder or a tilted potential, revealing signatures of anomalous subdiffusion in accompany with the breakdown of thermalization. Our work demonstrates a scalable method of probing infinite-temperature spin transport on analog quantum simulators, which paves the way to study other intriguing out-of-equilibrium phenomena from the perspective of transport.