Experimental observation of steady state decoherence in quantum nonlinear optics across EIT to ATS crossover

Hyperfine ground states in alkali atoms are among the most promising candidates for realizing high fidelity quantum circuits for scalable quantum information processing architecture. Fast manipulation of ground states can be realized via two-photon transitions driven by lasers. As a side effect, the atom-light interaction can cause decoherence in the system. Decoherence is an extremely fast process triggered by environmental factors during atom-light interaction that transforms macroscopic quantum superpositions into statistical mixtures.

We have measured a steady state behavior of decoherence using accurate lineshape

spectroscopy involving hyperfine ground states of D2 transition in ¹³³Cs atomic vapor. We experimentally attribute the steady state to a quantum nonlinear phenomenon originating from driven dissipative light-matter interaction in the presence of long ground-state-coherence and thermally driven dissipation channels. Our results show universal behavior across electromagnetically induced transparency (EIT) to Autler-Townes splitting (ATS) crossover. This offers an interesting opportunity for implementing quantum information processing protocols using atoms and photons across a large parameter range.