Andreev bound states formation and quasiparticle trapping in quench dynamics revealed by time-dependent counting statistics

TL;DR

This paper investigates the dynamics of Andreev bound states and quasiparticle trapping in superconducting nanojunctions during quantum quenches, revealing metastable states and universal behaviors through time-dependent counting statistics.

Contribution

It introduces a time-dependent Full Counting Statistics approach to analyze non-equilibrium populations of Andreev states in quantum quenches, highlighting universal behavior in the quantum point contact limit.

Findings

System gets trapped in metastable states without external relaxation.

Universal behavior depends only on Andreev state energy.

Results explain quasiparticle trapping observed experimentally.

Abstract

We analyze the quantum quench dynamics in the formation of a phase-biased superconducting nanojunction. We find that in the absence of an external relaxation mechanism and for very general conditions the system gets trapped in a metastable state, corresponding to a non-equilibrium population of the Andreev bound states. The use of the time-dependent Full Counting Statistics (FCS) analysis allows us to extract information on the asymptotic population of even and odd manybody states, demonstrating that a universal behavior, dependent only on the Andreev states energy, is reached in the quantum point contact limit. These results shed light on recent experimental observations on quasiparticle trapping in superconducting atomic contacts.