Higgs-like pair amplitude dynamics in superconductor-quantum dot hybrids

TL;DR

This paper studies how a quantum dot coupled to superconductors exhibits dynamic behavior of induced pair amplitudes, revealing decay and oscillation phenomena similar to Higgs and Nambu-Goldstone modes.

Contribution

It introduces a real-time diagrammatic approach to analyze the nonequilibrium dynamics of induced pair amplitudes in superconductor-quantum dot hybrids under quenches and periodic driving.

Findings

Quench dynamics show exponential decay towards equilibrium.

Periodic driving sustains coherent oscillations of pair amplitude.

Oscillations resemble Higgs and Nambu-Goldstone modes.

Abstract

We consider a quantum dot weakly tunnel coupled to superconducting reservoirs. A finite superconducting pair amplitude can be induced on the dot via the proximity effect. We investigate the dynamics of the induced pair amplitude after a quench and under periodic driving of the system by means of a real-time diagrammatic approach. We find that the quench dynamics is dominated by an exponential decay towards equilibrium In contrast, the periodically driven system can sustain coherent oscillations of both the amplitude and the phase of the induced pair amplitude in analogy to Higgs and Nambu-Goldstone modes in driven bulk superconductors.