Optical spectroscopy is used to study a material by measuring the intensity of light modes that scatter off it. In this work, we develop a theory for G2 spectroscopy of correlated materials, where instead of measuring the intensity of scattered photons, one measures the second order coherence between pairs of photons scattered off a material. We map this correlation function of the photons to the correlation functions of the material being probed. We specialize to Mott insulators in a single-band Hubbard model at half-filling, and find that depending both on the degree and region of frequency selectivity of the detectors, the photon G2 correlation function can map on to a slew of spin-spin and spin-charge correlation functions of the material. We illustrate the use of this technique by calculating some of these correlation functions both in an ordered phase – a square lattice antiferromagnet within linear spinwave theory and in a quantum spin-liquid – the Kitaev Honeycomb model.

Pizza and drinks will be served after the seminar in ATL 2117.