Dynamical Response of Fermi Condensate to Varying Magnetic Fields

TL;DR

This paper studies how ultra-cold fermionic atoms near Feshbach resonance respond dynamically to changing magnetic fields, revealing linear and non-linear behaviors, resonance phenomena, and dependence on ramping rates.

Contribution

It provides a detailed analysis of the dynamical response of Fermi condensates to magnetic field variations, including spectral and time-domain insights, which advances understanding of non-equilibrium behaviors.

Findings

Response shows linear and non-linear behaviors depending on oscillation parameters.

Existence of a resonant frequency related to pair dissociation threshold.

Final excitation gap depends on the rate of magnetic field ramping.

Abstract

We investigate the dynamical response of strongly interacting ultra-cold fermionic atoms near Feshbach resonance to varying magnetic fields. Following the experimental practices, we calculate the response of the atoms to oscillating and to linearly ramped magnetic fields respectively. For oscillating magnetic fields, depending on the frequencies and the amplitudes of the oscillations, the response of the pair excitation gap shows either linear or rich non-linear behaviour. In addition, both the spectral studies through the linear response theory and the time-domain simulations suggest the existence of a resonant frequency corresponding to the pair dissociation threshold. For linearly ramped magnetic fields, the response of the excitation gap shows damped oscillations. The final value of the excitation gap depends on the rate of the field sweep.