Multidimensional spectroscopy in optical cavities based on photon correlations

Quantum electrodynamical effects in microcavities provide a powerful tool for studying quantum effects in matter which include the manipulation of chemical reactions rates and outcomes. These can be described by the Jaynes-Cummings model which represents a two-level atom interacting with quantized cavity modes and is a pillar of modern quantum optics. The time dependence in matter-cavity coupling resembles molecular dynamics and is a cornerstone of the studies of molecular dynamics in cavities. Here we show that the response of a two-level atom to the time-dependent coupling to a single cavity mode can be monitored by a new type of time-and-frequency resolved photon correlation measurements of spontaneous emission into noncavity modes. This novel multidimensional optical spectroscopy technique is based on single photon counting and can monitor the atom-cavity dressed state population and coherence dynamics for a given cavity photon number. Simultaneous time-and-frequency gating allows to precisely determine the hybrid state of molecule plus cavity without interfering with the cavity photon statistics.