Control of a quantum emitter's bandwidth by managing its reactive power

TL;DR

This paper reveals that reactive power significantly influences the bandwidth of quantum emitters, offering new ways to engineer narrowband and efficient quantum light sources by understanding reactive power as a controllable degree of freedom.

Contribution

It introduces the concept that reactive power can be used to control quantum emitter bandwidth, bridging a gap between weak and strong coupling regimes and expanding quantum emitter design strategies.

Findings

Reactive power affects quantum emitter bandwidth in an intermediate regime.

Reactive power dispersion properties are linked to emitter bandwidth.

Designs for narrowband, efficient photon sources are proposed.

Abstract

Reactive power plays a crucial role in the design of small antenna systems, but its impact on the bandwidth of quantum emitters is typically disregarded. Here, we theoretically demonstrate that there is an intermediate domain between the usual weak and strong coupling regimes where the bandwidth of a quantum emitter is directly related to the dispersion properties of the reactive power. This result emphasizes that reactive power must be understood as an additional degree of freedom in engineering the bandwidth of quantum emitters. We illustrate the applicability of this concept by revisiting typical configurations of quantum emitters coupled to resonant cavities and waveguides. Analysis of the reactive power in these system unveils new functionalities, including the design of effcient but narrowband photon sources, as well as quantum emitters exhibiting a bandwidth narrower than its nonradiative linewidth.