Triggered Superradiance and Inversion Storage in a Hybrid Quantum System

TL;DR

This paper investigates superradiant emission in a hybrid quantum system, demonstrating controlled inversion storage, triggered superradiance, and microwave pulse amplification using a spin ensemble coupled to a superconducting cavity.

Contribution

It introduces a method to store inversion in a spin ensemble, trigger superradiance with a weak pulse, and utilize stored energy for microwave amplification.

Findings

Inversion can be stored for tens of milliseconds.

A weak trigger pulse can control superradiant emission timing.

Stored energy can amplify microwave signals.

Abstract

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.