Strong interactions in a fully integrated vapor cavity QED platform*

We present a fully integrated platform that combines warm rubidium (Rb) vapor with high-Q (~10^5) photonic microcavities on a chip. By using pulsed activation of an alkali dispenser pill, we achieve temperature-independent control of Rb density, enabling tunable cavity interactions. We also show that by varying the duty cycle of a series of gated activation laser pulses, we can establish a quasi-stable Rb density. We verify this pulsed scheme through free-space and waveguide-coupled absorption measurements. Under these conditions, we observe strong coupling between an ensemble of Rb atoms and the high-Q microcavity, revealing robust cavity QED phenomena in a microfabricated device. We are currently investigating methods to prevent degradation of the cavity quality factor during Rb dispensing, such as applying a heating laser coupled to the same ring resonator. Moving forward, we aim to extend these cavity QED experiments toward the single-atom, single-photon regime, through further control of the Rb density and use of ultra-small volume photonic crystal cavities.