Optimization of selective two-photon absorption in cavity polaritons

TL;DR

This paper explores how quantum correlations in entangled photon pairs can optimize two-photon absorption in multilevel quantum systems, improving selectivity despite interference and nearby states.

Contribution

It demonstrates that optimal entangled states of light can enhance selective excitation in quantum systems, especially with broader linewidths, surpassing separable states.

Findings

Quantum correlations improve selectivity in two-photon excitation.

Optimal entangled states outperform separable states in certain conditions.

Enhanced selectivity increases with broader linewidths of target states.

Abstract

We investigate optimal states of photon pairs to excite a target transition in a multilevel quantum system. With the help of coherent control theory for two-photon absorption with quantum light, we infer the maximal population achievable by optimal entangled vs. separable states of light. Interference between excitation pathways, as well as the presence of nearby states, may hamper the selective excitation of a particular target state, but we show that quantum correlations can help to overcome this problem, and enhance the achievable "selectivity" between two energy levels, i.e. the relative difference in population transferred into each of them. We find that the added value of optimal entangled states of light increases with broadening linewidths of the target states.