Precision Measurements of Atom-Dimer Interactions in a Uniform Planar Bose Gas

TL;DR

This paper reports precise measurements of atom-dimer interactions in a uniform Bose gas of rubidium-87, including scattering lengths and energy levels, using microwave photoassociation techniques.

Contribution

It provides the first detailed measurement of atom-dimer scattering lengths and energy diagrams in a uniform Bose gas, advancing understanding of mixed atomic and molecular quantum gases.

Findings

Measured atom-dimer scattering lengths for two molecular states.

Mapped the complete energy diagram of a hyperfine molecular state.

Reproduced energy levels with a simple theoretical model.

Abstract

Cold quantum gases, when acted upon by electromagnetic fields, can give rise to samples where isolated atoms coexist with dimers or trimers, which raises the question of the interactions between these various constituents. Here we perform microwave photoassociation in a degenerate gas of $^{87}$Rb atoms to create weakly-bound dimers in their electronic ground state. From the density-induced shift of the photoassociation line, we measure the atom-dimer scattering length for the two least-bound states of the molecular potential. We also determine the complete energy diagram of one hyperfine manifold of the least-bound state, which we accurately reproduce with a simple model.