Many-body localization in an array of superconducting qubits and the nucleation of ergodicity

Michele Filippone (University of Geneva)

I will illustrate an experiment in which an array of superconducting qubits probes the exotic dynamics of interacting and disordered bosons [1]. In particular, we probed the mechanism of many-body localization (MBL) -- a generalization of Anderson localization in the presence of interactions.  Relying on real-time and interferometric probes, we observed the persistence of localization in the presence of interactions, established the emergence of effective, non-local interactions, and probed the slow growth of entanglement. These features are all specific to MBL.
I will then discuss a remarkably simple mechanism in which a single interacting impurity triggers the generation of ergodic bubbles, able to thermalize extensive localized systems. I will provide analytical estimates, supported by numerical simulations, showing how the critical disorder strength for such mechanism depends on singlon densities. I will then discuss the importance of this mechanism for ongoing experimentssimulating synthetic quantum lattices. [2]

[1] https://arxiv.org/abs/1910.06024
[2] https://arxiv.org/abs/1911.11711