Four-Wave mixing in degenerate Fermi gases: Beyond the undepleted pump approximation

TL;DR

This paper investigates the nonlinear dynamics of four-wave mixing in degenerate Fermi gases beyond the undepleted pump approximation, revealing conditions for sustained mixing and enhanced efficiency.

Contribution

It introduces a full nonlinear analysis of four-wave mixing in fermionic gases, showing how back-action effects can prolong mixing and improve efficiency.

Findings

Dephasing suppression when beam and grating atom numbers are comparable

Large nonlinear coupled amplitude oscillations observed

Enhanced four-wave mixing efficiency with initial density grating

Abstract

We analyze the full nonlinear dynamics of the four-wave mixing between an incident beam of fermions and a fermionic density grating. We find that when the number of atoms in the beam is comparable to the number of atoms forming the grating, the dephasing of that grating, which normally leads to a decay of its amplitude, is suppressed. Instead, the density grating and the beam density exhibit large nonlinear coupled amplitude oscillations. In this case four-wave mixing can persist for much longer times compared to the case of negligible back-action. We also evaluate the efficiency of the four-wave mixing and show that it can be enhanced by producing an initial density grating with an amplitude that is less than the maximum value. These results indicate that efficient four-wave mixing in fermionic alkali gases should be experimentally observable.