Polaron in a non-abelian Aubry-Andr\'e-Harper model with \textit{p}-wave superfluidity

TL;DR

This paper studies how a mobile impurity behaves in a one-dimensional topological p-wave superfluid with quasi-periodic disorder, revealing distinct polaron phases that mirror the background system's phases and can be experimentally probed.

Contribution

It introduces a variational approach to analyze polaron phases in a topological p-wave superfluid with disorder, linking polaron states to the underlying Fermi system phases.

Findings

Four distinct polaron phases identified: two extended, one weakly-localized, one strongly-localized.

Polaron phases directly correspond to phases of the background Fermi system.

p-wave pairing influences many-body localization and thermalization.

Abstract

We theoretically investigate the behavior of a mobile impurity immersed in a one-dimensional quasi-periodic Fermi system with topological $p$-wave superfluidity. This polaron problem is solved by using a standard variational approach, the so-called Chevy ansatz. The polaron states are found to be strongly affected by the strength of the quasi-disorder and the amplitude of the $p$-wave pairing. We analyze the phase diagram of the polaron ground state and find four phases: two extended phases, a weakly-localized phase and a strongly-localized phase. It is remarkable that these polaron phases are directly corresponding to the four distinct phases experienced by the underlying background Fermi system. In particular, the weakly-localized polaron phase corresponds to an intriguing critical phase of the Fermi system. Therefore, the different phases of the background system can be unambiguously probed by measuring the polaron properties via radio-frequency spectroscopy. We also investigate the high-lying excited polaron states at an infinite temperature and address the possibility of studying many-body localization (MBL) of these states. We find that the introduction of $p$-wave pairing may delocalize the many-body localized states and make the system easier to thermalize. Our results could be observed in current state-of-the-art cold-atom experiments.