Exceptional Point Superradiant Lasing with Ultranarrow Linewidth

TL;DR

This paper theoretically demonstrates superradiant lasing with an ultranarrow linewidth in the microhertz range by exploiting the exceptional point in a $ ext{PT}$-symmetric system of ultracold strontium-87 atoms, promising advances in atomic clock stability.

Contribution

It introduces the use of the exceptional point to significantly narrow the linewidth of superradiant lasing, extending the capabilities of quantum precision measurement.

Findings

Linewidths in the microhertz range achieved

Ultranarrow linewidths are three orders of magnitude smaller than in systems without EP

Enhanced atomic coherence at the exceptional point

Abstract

Achieving superradiant lasing with an ultranarrow linewidth is crucial for enhancing atomic clock stability in quantum precision measurement. By employing the exceptional point (EP) property of the system, we demonstrate theoretically superradiant lasing with linewidths in the $\mu$Hz range, sustained at the high-power level. This is achieved by incoherently pumping optical lattice clock transitions with ultracold alkaline-earth strontium-87 atoms in the EP of a $\mathcal{PT}$-symmetric system. Physically, the atomic coherence reaches a maximum in the EP, significantly amplifying the superradiance effect and resulting in superradiant lasing with an ultranarrow linewidth. This linewidth is even three orders of magnitude smaller than that of superradiant lasing in the systems without EP. Our work extends the realm of superradiant lasing by introducing the EP property, and offers promising applications for developing atomic clocks with exceptional stability and accuracy.