Quantum Enhanced Nonlinear Spectroscopy of Strongly Coupled Microcavities

The use of quantum entangled photons is suggested as a way to improve upon limitations in measurement sensitivity in conventional nonlinear optical spectroscopy. In addition, time-frequency entangled photon probes can potentially enable isolation of specific many-body interactions in condensed matter. Here, we discuss an experimental implementation of a nonlinear spectroscopy system based on spectrally entangled biphoton states. Using modified Mach-Zehnder interferometry, we present a methodology to estimate spectral correlations between entangled photons, which are generated through spontaneous parametric down-conversion of ultrashort optical pulses. We observe that the correlations in the biphoton state, characterized by the two-dimensional joint spectral amplitude (JSA), are transformed due to matter interactions. Specifically, we explore estimation of many-body interactions of polaritons in a strongly coupled semiconductor microcavity through an in-depth analysis of the experimentally obtained JSA of the biphoton state transmitted through the microcavity.<br/><br/><br/>Reference:<br/><br/>Moretti et al. (2023). “Measurement principles for quantum spectroscopy of molecular materials with entangled photons”. arXiv:2304.07828