Cavity-enabled real-time observations and manipulation of many-atom dynamics*

We report on the use of strong dispersive coupling in a high-cooperativity optical cavity to achieve fast, nondestructive, number-resolved detection of atoms confined in optical tweezers. Continuous monitoring of cavity transmission enables real-time observation of dynamic processes such as individual atom-atom collisions, quantum state jumps, and atom loss events, with a temporal resolution of 100 µs. Leveraging adaptive feedback control in conjunction with this nondestructive measurement technique, we demonstrate the preparation of a single atom with 92(2)% probability. This work highlights the power of optical cavities for advancing neutral-atom quantum computing while opening new opportunities in fundamental atomic physics and the study of cold atom collisions.