Emergence of synchronisation in a driven-dissipative hot Rydberg vapor

We observe synchronisation in a thermal (35-60 {\deg}C) atomic (Rb) ensemble driven to a highly-excited Rydberg state (principle quantum number n ranging from 43 to 79). Synchronisation in this system is unexpected due to the atomic motion, however, we show theoretically that sufficiently strong interactions via a global Rydberg density mean field causes frequency and phase entrainment. The emergent oscillations in the vapor's bulk quantities are detected in the transmission of the probe laser for a two-photon excitation scheme.