Preparation of one 87Rb and one 133Cs atom in a single optical tweezer

We report the preparation of exactly one Rb-87 atom and one Cs-133 atom in the same optical tweezer as the essential first step towards the construction of a tweezer array of individually trapped (RbCs)-Rb-87-Cs-133 molecules. Through careful selection of the tweezer wavelengths, we show how to engineer species-selective trapping potentials suitable for high-fidelity preparation of Rb + Cs atom pairs. Using a wavelength of 814 nm to trap Rb and 938 nm to trap Cs, we achieve loading probabilities of 0.508(6) for Rb and 0.547(6) for Cs using standard red-detuned molasses cooling. Loading the traps sequentially yields exactly one Rb and one Cs atom in 28.4(6)% of experimental runs. Using a combination of an acousto-optic deflector and a piezo-controlled mirror to control the relative position of the tweezers, we merge the two tweezers, retaining the atom pair with a probability of 0.99((-0.02))((+0.01)). We use this capability to study hyperfine-state-dependent collisions of Rb and Cs in the combined tweezer and compare the measured two-body loss rates with coupled-channel quantum scattering calculations.

Automated summary

In this study, exactly one Rb-87 atom and one Cs-133 atom were prepared in the same optical tweezer, serving as the essential first step towards constructing a tweezer array of (RbCs)-Rb-87-Cs-133 molecules. By carefully selecting the tweezer wavelengths, species-selective trapping potentials suitable for high-fidelity preparation of Rb + Cs atom pairs were engineered. The merging of two tweezers was achieved using an acousto-optic deflector and a piezo-controlled mirror, retaining the atom pair with a high probability of 0.99((-0.02))((+0.01)).