Superradiance of nitrogen-vacancy spin ensembles in two experiments

Short answer: Superradiance is a collective effect in which many emitters radiate together far faster than any one would alone. Two experiments with nitrogen-vacancy (NV) centre spins in diamond coupled to a microwave resonator report it: a 2018 paper observed a superradiant pulse a trillion times faster than single-centre decay, and a 2025 paper reported a train of pulses and masing driven by spin-spin interactions. These are laboratory experiments.

What is superradiance in a spin ensemble?

The 2018 Nature Physics abstract describes superradiance as a fundamental collective effect where radiation is amplified by the coherence of multiple emitters. It notes that superradiance plays a prominent role in optics, where it enables lasers with substantially reduced linewidths, and in quantum mechanics. The authors say resonators coupled to spin ensembles are promising building blocks of integrated quantum devices that will involve superradiance, so its fundamental properties in such devices should be studied. Although strong-coupling experiments had shown oscillatory behaviour, they say a clear signature of Dicke superradiance had been missing.

What did the 2018 experiment observe?

The authors explore superradiance in a system composed of a three-dimensional lumped-element resonator, in the fast cavity limit, inductively coupled to an inhomogeneously broadened ensemble of NV centres. They observe a superradiant pulse emitted a trillion times faster than the decay of an individual NV centre. They confirm this with the nonlinear scaling of the emitted radiation intensity with ensemble size. They say the work provides a foundation for future quantum devices based on spin ensembles, which is an outlook.

What did the 2025 experiment add?

The 2025 Nature Physics paper, which also appeared as a 2024 arXiv preprint, starts from the usual assumption in cavity quantum electrodynamics that emitters are independent and interact only through light in a shared mode. Direct dipole-dipole interactions within the ensemble are generally viewed as a source of decoherence. The authors report instead that direct spin-spin interactions drive the superradiant dynamics of a hybrid system of NV spins in diamond coupled to a superconducting microwave cavity. After an initial fast superradiant burst, they observe a train of subsequent emission pulses followed by quasi-continuous masing for up to one millisecond.

They show this arises from spectral hole refilling, where spin inversion is redistributed into the superradiant window of spins resonant with the cavity. They report measurements that exclude other cavity-related effects, and perform microscopic simulations, with up to one million spins in the preprint version, that confirm the behaviour is driven by dipole-dipole interactions. They say the findings open pathways for exploring complex spin-spin interactions in dense disordered systems, and offer possibilities for ultranarrow-linewidth solid-state superradiant devices. Those are possibilities, and no device is reported.

How to read this

The 2024 preprint and the 2025 journal paper are the same work, so this post covers two distinct studies. Masing is microwave amplification by stimulated emission, the microwave counterpart of lasing. The reported numbers are the authors' own. This post is based on abstracts, and full texts were not checked. It makes no claim about products. For other uses of the same defects, see our posts on NV sensing.

FAQ

What is Dicke superradiance?

Collective emission from many emitters that is much faster than single-emitter decay, as described in the 2018 abstract.

How much faster was the 2018 pulse?

A trillion times faster than a single NV centre's decay, per the authors.

What was new in 2025?

Direct spin-spin interactions drove a pulse train and masing for up to one millisecond.

Is this a working device?

No. The papers describe physics experiments and name devices as possibilities.