Strong Coupling on a Forbidden Transition in Strontium and Nondestructive Atom Counting

TL;DR

This paper demonstrates strong collective coupling on a forbidden transition in strontium, enabling non-destructive atom counting with high sensitivity, which could improve optical lattice clock performance through entanglement and reduced dead time.

Contribution

It reports the first observation of strong coupling on a forbidden transition in strontium and introduces a non-destructive measurement technique for atomic populations.

Findings

Observed vacuum Rabi splitting on a forbidden transition.

Achieved projection-noise limited sensitivity with minimal heating.

Potential application in enhancing optical lattice clocks.

Abstract

We observe strong collective coupling between an optical cavity and the forbidden spin singlet to triplet optical transition $^1$S$_0$ to $^3$P$_1$ in an ensemble of $^{88}$Sr. Despite the transition being 1000 times weaker than a typical dipole transition, we observe a well resolved vacuum Rabi splitting. We use the observed vacuum Rabi splitting to make non-destructive measurements of atomic population with the equivalent of projection-noise limited sensitivity and minimal heating ($<0.01$ photon recoils/atom). This technique may be used to enhance the performance of optical lattice clocks by generating entangled states and reducing dead time.