Experimental characterization of the quantum many-body localization transition

As strength of disorder enhances beyond a threshold value in many-body systems, a fundamental transformation happens through which the entire spectrum localizes, a phenomenon known as many-body localization. This has profound implications as it breaks down fundamental principles of statistical mechanics, such as thermalization and ergodicity. Due to the complexity of the problem, the investigation of the many-body localization transition has remained a big challenge. The experimental exploration of the transition point is even more challenging as most of the proposed quantities for studying such an effect are practically infeasible. Here, we experimentally implement a scalable protocol for detecting the many-body localization transition point, using the dynamics of an N = 12 superconducting qubit array. We show that the sensitivity of the dynamics to random samples becomes maximum at the transition point, which leaves its fingerprints in all spatial scales. By exploiting three quantities, each with a different spatial resolution, we identify the transition point with an excellent match between simulation and experiment. In addition, one can detect the evidence of a mobility edge through slight variation of the transition point as the initial state varies. The protocol is easily scalable and can be performed across various physical platforms.

Automated summary

As disorder strength exceeds a threshold value in many-body systems, a transformation known as many-body localization occurs, breaking down fundamental principles of statistical mechanics. Investigating the transition point remains challenging, but detecting it experimentally is possible by exploiting the sensitivity of dynamics to random samples, leaving fingerprints on all spatial scales. Additionally, evidence of a mobility edge can be detected by slight variations of the transition point with changes in the initial state, and the scalable protocol can be implemented across various physical platforms.