No oscillating subradiant correlations in a strongly driven quantum emitter array

Abstract: We theoretically study time-dependent correlations in a strongly driven array of $N$ two-level atoms, coupled to photons in a waveguide. We focus on the spectrum ${\lambda}$ of the Liouvillian superoperator, which determines the correlation decay rates $-\Re \lambda$ and the frequencies $\Im\lambda$. Our main finding is the suppression of subradiant oscillating correlations between atomic states by a strong coherent of amplitude $\Omega$: $|\Re \lambda|\ge m\gamma/2$, where $\gamma$ is the single-atom spontaneous decay rate and $m=|\Im \lambda/(2\Omega)|$ is a nonzero integer for correlations oscillating in time $\propto \exp(\pm 2i m|\Omega| t)$. This limit is independent of the number of atoms $N$; it holds both for small arrays and in the macroscopic limit. We demonstrate the suppression of subradiance numerically and provide a rigorous proof based on the analytical decomposition of the Liouvillian using spectral theory of simplicial complexes and posets.