Sensitivity test of a blue-detuned dipole trap designed for parity non-conservation measurements in Fr

TL;DR

This paper presents a blue-detuned optical dipole trap for rubidium atoms, demonstrating long coherence times and a method to calibrate sensitivity for parity non-conservation experiments in francium.

Contribution

It introduces a stable, dynamic blue-detuned trap with long coherence times and a phase-locked microwave technique for sensitivity calibration in PNC measurements.

Findings

Differential ac Stark shift of 18 Hz in ground state hyperfine transition

Coherence time of 180 ms for hyperfine superpositions

Effective phase-locked microwave interference method for sensitivity calibration

Abstract

A dynamic blue-detuned optical dipole trap with stable $^{87}Rb$ atoms produces a differential ac Stark shift of 18 Hz in the ground state hyperfine transition, and it preserves the ground state hyperfine superpositions for a long coherence time of 180 ms. The trapped atoms undergoing microwave Rabi oscillations are sensitive to a small signal, artificially generated with a second microwave source, phase locked to the first allow- ing a simple and effective method for determining signal-to-noise ratio limits through interference techniques. This provides an excellent means of calibrating sensitivity in experiments such as our ongoing Fr parity non-conservation measurement.