Proposal for room-temperature superradiant echoes induced by multiple re-phasing of frequency-grated NV spin sub-ensembles

In this article, we propose that superradiant echoes can be achieved at room temperature by applying a laser illumination and a microwave Hahn echo sequence to a diamond with a high concentration of nitrogen-vacancy (NV) centers placed in a dielectric microwave cavity. We identify that the combined action of two microwave driving pulses and a free evolution imprints a frequency grating among NV spin sub-ensembles, and the multiple re-phasing of the grated spin sub-ensembles leads to multiple superradiant echoes through a collective coupling with the cavity. Furthermore, we show that the superradiant echoes can be actively tailored through the microwave pulses and the laser illumination by adjusting the grating parameters, and the multiple re-phasing dynamics is analogous to the one leading to superradiant beats in atomic optical clock systems. In the future, the spin sub-ensembles grating and the resulting echoes can be further optimized with dynamical decoupling, which might pave the way for applications in quantum sensing.