Optical excitation of nonlinear spin waves

TL;DR

This paper introduces a method to excite and study nonlinear spin waves in ultracold Rb-87 gases using tunable AC Stark potentials, revealing amplitude-dependent frequencies and complex behaviors.

Contribution

The work presents a novel optical technique for exciting arbitrary spin wave modes in ultracold gases, enabling detailed exploration of their nonlinear dynamics.

Findings

Successful excitation of multiple spin wave modes including dipole to hexadecapole.

Observation of strong nonlinear effects such as amplitude-dependent frequencies.

Results align well with quantum Boltzmann transport equation predictions.

Abstract

We demonstrate a technique for exciting spin waves in an ultracold gas of Rb-87 atoms based on tunable AC Stark potentials. This technique allows us to excite normal modes of spin waves with arbitrary amplitudes in the trapped gas, including dipole, quadrupole, octupole, and hexadecapole modes. These modes exhibit strong nonlinearities, which manifest as amplitude dependence of the excitation frequencies and departure from sinusoidal behavior. Our results are in good agreement with a full treatment of a quantum Boltzmann transport equation.