Preparation of one $^{87}$Rb and one $^{133}$Cs atom in a single optical tweezer

Abstract

We report the preparation of exactly one 87 Rb atom and one 133 Cs atom in the same optical tweezer as the essential first step towards the construction of a tweezer array of individually trapped 87 Rb 133 Cs 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 (+0.01) (−0.02) . 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.