Triggered Superradiance and Spin Inversion Storage in a Hybrid Quantum System

We study the superradiant emission of an inverted spin ensemble strongly coupled to a superconducting cavity. After fast inversion, we detune the spins from the cavity and store the inversion for tens of milliseconds, during which the remaining transverse spin components disappear. Switching back on resonance enables us to study the onset of superradiance. A weak trigger pulse of a few hundred photons shifts the superradiant burst to earlier times and imprints its phase onto the emitted radiation. For long hold times, the inversion decreases below the threshold for spontaneous superradiance. There, the energy stored in the ensemble can be used to amplify microwave pulses passing through the cavity.

Automated summary

We investigate the superradiant emission of an inverted spin ensemble strongly coupled to a superconducting cavity. By rapidly inverting the spins and detuning them from the cavity, we can store the inversion for tens of milliseconds and observe the disappearance of the remaining transverse spin components. Triggering the resonance allows us to study the onset of superradiance, with a weak pulse shifting the superradiant burst to earlier times and imprinting its phase onto the emitted radiation. For long hold times, the inversion decreases below the threshold for spontaneous superradiance, enabling the amplification of microwave pulses using the stored energy in the ensemble passing through the cavity.