Intermode-coupling modulation in the fermion-boson model: heating effects in the BCS regime

TL;DR

This paper investigates how oscillating interaction strength in a fermion-boson system causes heating and damping effects in a fermion condensate, highlighting the role of nonadiabatic excitations and quasiparticle generation.

Contribution

It introduces a generalized time-dependent intermode coupling in the fermion-boson model and analytically characterizes the resulting heating effects in the BCS regime.

Findings

Damped and delayed condensate response to modulation

Heating occurs when driving frequency exceeds twice the pairing gap

Quasiparticle excitations are responsible for damping and heating

Abstract

Heating induced by an oscillating modulation of the interaction strength in an atomic Fermion pair condensate is analyzed. The coupled fermion-boson model, generalized by incorporating a time-dependent intermode coupling through a magnetic Feshbach resonance, is applied. The dynamics is analytically characterized in a perturbative scheme. The results account for experimental findings which have uncovered a damped and delayed response of the condensate to the modulation. The delay is due to the variation of the quasiparticle energies and the subsequent relaxation of the condensate. The detected damping results from the excitations induced by a nonadiabatic modulation: for driving frequencies larger than twice the pairing gap, quasiparticles are generated, and, consequently, heating sets in.