Breakdown of atomic hyperfine coupling in a deep optical-dipole trap

TL;DR

This study investigates how hyperfine coupling in a single rubidium atom breaks down in a deep optical trap, revealing nonlinear effects, line splitting, and forbidden transitions, and measures related atomic properties.

Contribution

It provides experimental evidence of hyperfine breakdown in a deep optical-dipole trap and quantifies related atomic parameters for rubidium.

Findings

Nonlinear dependence of transition frequencies on trap intensity

Splitting of degenerate spectral lines at high intensities

Observation of forbidden transitions enabled by hyperfine breakdown

Abstract

We experimentally study the breakdown of hyperfine coupling for an atom in a deep optical-dipole trap. One-color laser spectroscopy is performed at the resonance lines of a single $^{87}$Rb atom for a trap wavelength of 1064 nm. Evidence of hyperfine breakdown comes from three observations, namely a nonlinear dependence of the transition frequencies on the trap intensity, a splitting of lines which are degenerate for small intensities, and the ability to drive transitions which would be forbidden by selection rules in the absence of hyperfine breakdown. From the data, we infer the hyperfine interval of the $5P_{1/2}$ state and the scalar and tensor polarizabilities for the $5P_{3/2}$ state.