JILA Thesis Defense - Zhijing Niu

About this event

Title: Many-body physics and superradiance in a strontium optical ring cavity

Speaker : Zhijing Niu

Event Details / Abstract : Strontium cavity QED systems provide a versatile platform for exploring many-body physics and superradiance. We demonstrate cavity-mediated suppression of Doppler dephasing on the 7.5 kHz 1S0–3P1 transition, extending dipole coherence beyond the independent-atom limit through all-to-all spin-exchange interactions without Lamb-Dicke confinement. We realize hours-long continuous recoil-driven lasing from laser-cooled 88Sr in a ring cavity, sustained by Raman gain between momentum states, with 120-fold reduced cavity-frequency sensitivity. On the ultranarrow clock transition, we observe preseeded and spontaneous pulsed superradiance from 87Sr and study competition between clockwise and counterclockwise modes during transport, advancing toward a continuously operating active optical frequency reference.