Spin waves and Collisional Frequency Shifts of a Trapped-Atom Clock

TL;DR

This paper investigates how spin-waves in a trapped-atom clock cause density-dependent frequency shifts, revealing complex behaviors including reversals and beyond mean-field effects, supported by models.

Contribution

It introduces a method to excite spin-waves and analyzes their impact on frequency shifts, highlighting novel beyond mean-field effects in trapped-atom clocks.

Findings

Spin-waves induce reversible frequency shifts in the clock.

Frequency shifts depend on the second Ramsey pulse area.

Models accurately predict observed spin-wave behaviors.

Abstract

We excite spin-waves with spatially inhomogeneous pulses and study the resulting frequency shifts of a chip-scale atomic clock of trapped $^{87}$Rb. The density-dependent frequency shifts of the hyperfine transition simulate the s-wave collisional frequency shifts of fermions, including those of optical lattice clocks. As the spin polarizations oscillate in the trap, the frequency shift reverses and it depends on the area of the second Ramsey pulse, exhibiting a predicted beyond mean-field frequency shift. Numerical and analytic models illustrate the observed behaviors.