Nonreciprocal interactions induce frequency shifts in superradiant lasers

TL;DR

This paper demonstrates that nonreciprocal interactions between driven and undriven atoms in superradiant lasers cause frequency shifts and linewidth broadening, impacting their stability and performance.

Contribution

It reveals the role of nonreciprocal interactions in superradiant lasers, a previously underexplored factor affecting their coherence and stability.

Findings

Frequency shifts occur when some atoms are undriven.

Linewidth broadening is caused by nonreciprocal interactions.

Implications for improving superradiant laser design.

Abstract

Superradiant lasers, which consist of incoherently driven atoms coupled to a lossy cavity, are a promising source of coherent light due to their stable frequency and superior narrow linewidth. We show that when a fraction of the atoms is not driven, a shift in the lasing frequency and a broadening of the linewidth occur, limiting the performance of a superradiant laser. We explain this behavior by identifying nonreciprocal interactions between driven and undriven atoms, i.e., competing alignment and antialignment of their dipoles. Our results have implications for the realization of superradiant lasers, establishing the relevance of nonreciprocal phenomena for quantum technologies.