Thermally robust spin correlations between two 85Rb atoms in an optical microtrap

Abstract

The complex collisional properties of atoms fundamentally limit investigations into a range of processes in many-atom ensembles. In contrast, the bottom-up assembly of few- and many-body systems from individual atoms offers a controlled approach to isolating and studying such collisional processes. Here, we use optical tweezers to individually assemble pairs of trapped 85 Rb atoms, and study the spin dynamics of the two-body system in a thermal state. The spin-2 atoms show strong pair correlation between magnetic sublevels on timescales exceeding one second, with measured relative number fluctuations 11.9 ± 0.3 dB below quantum shot noise, limited only by detection efficiency. Spin populations display relaxation dynamics consistent with simulations and theoretical predictions for 85 Rb spin interactions, and contrary to the coherent spin waves witnessed in finite-temperature many-body experiments and zero-temperature two-body experiments. Our experimental approach offers a versatile platform for studying two-body quantum dynamics and may provide a route to thermally robust entanglement generation.

Observation of Collisions between Two Ultracold Ground-State CaF Molecules

“…Our approach ensures, by construction, that only single-body and two-body processes are at play, in contrast to previous measurements in bulk molecular gases. We note that with atoms, similar tweezerbased approaches have been used to probe hyperfine relaxation [43,44], coherent two-body dynamics [45], and Feshbach resonances [46].…”

Multichannel interactions of two atoms in an optical tweezer

“…More recently, single atoms trapped in optical tweezers have become widely pursued as a versatile experimental platform for studying few and manybody physics through bottom-up scaling [15][16][17][18][19][20][21][22][23]. An optical tweezer with only two atoms is a pristine environment for studying ultracold collisions [24][25][26] or for producing two-particle entanglement [19,27]. Optical tweezers are now even being used with molecules, where they can either assemble molecules from single ultracold atoms [25,28] or be used to directly trap single ultracold molecules [29].…”

The Renewed Role of Sweep Functions in Noisy Shortcuts to Adiabaticity

“…This error takes account of the potential imprecise or incomplete knowledge of both the actual coupling between the two levels, on the one hand, and of the exact level spacing at the beginning and at the end of the sweep. These types of errors are common, for instance, in experiments controlling single cold-atom collisions [ 41 , 42 , 43 ]. To track the impact of such an error on the performance of the counterdiabatic protocols, the system is initially prepared in state , and the final fidelity , i.e., the probability of being in the target state , is monitored as a function of the total time evolution and .…”