Scalable Room Temperature Quantum System Developments

Thermal atoms are an enticing platform for Cavity Quantum Electrodynamics (CQED) because they are easy to generate and highly scalable when compared with cold atom systems. A typical 1 mm³ rubidium (Rb) vapor cell above 100°C contians >Ο(10⁹) completely indistinguishable qunantum systems, providing an extremely large and easily accessible resource of quantum information if harnessed. Previous work on the design and development of micro-resonators has shown high quality-factor (Q) values around the ⁸⁷Rb optical transition frequency at 780 nm and the promise for strong interactions on the single photon level. Alkali vapor can degrade the Q irreversibly, so we are using collimated thermal Rb beams to avoid excess exposure and extend the lifetime of the micro-resonator Q-values. However, atom transit duration through the interaction mode volume for room temperature ensembles lasts approximately 40 ns. Although the interaction strength is enhanced by the cavity, the short duration provides a limit on the number of possible detected photons through the cavity per atom transit. One way to remedy this is to slow the atom velocity through the interaction volume. In a separate experiment, we demonstrate passive filtering of thermal beams to carefully select atoms whose three-dimensional velocity vector has a magnitude below v/20 . Without the aid of laser cooling, we have isolated and tracked very slowly moving individual atoms for >1 μs within a 25 μm field of view.