Lee-Huang-Yang effects in the ultracold mixture of 23Na and 87Rb with attractive interspecies interactions

The beyond-mean-field Lee-Huang-Yang (LHY) correction is ubiquitous in dilute ultracold quantum gases. However, its effects are often elusive due to the typically much larger influence of the mean-field (MF) energy. In this work, we study an ultracold mixture of Na-23 and Rb-87 with tunable attractive interspecies interactions. The LHY effects manifest in the formation of self-bound quantum liquid droplets and the expansion dynamics of the gas-phase sample. A liquid-to-gas-phase diagram is obtained by measuring the critical atom numbers below which the self-bound behavior disappears. In stark contrast to trapped gas-phase condensates, the gas-phase mixture formed following the liquid-to-gas-phase transition shows an anomalous expansion featuring a larger release energy for increasing MF attractions.

Automated summary

The study focuses on the beyond-mean-field Lee-Huang-Yang (LHY) correction in dilute ultracold quantum gases, particularly in an ultracold mixture of Na-23 and Rb-87 with tunable attractive interspecies interactions. The effects of LHY manifest in the formation of self-bound quantum liquid droplets and the expansion dynamics of the gas-phase sample. The research also reveals an anomalous expansion in the gas-phase mixture following the liquid-to-gas-phase transition, displaying a larger release energy with increasing MF attractions.