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FRI: Friday Contributed Sessions

FRI 12: Quantum Phenomena in Solid-State Devices

FRI 12.1: Vortrag

Freitag, 12. September 2025, 10:45–11:00, ZHG105

Probing many-body correlations using quantum-cascade correlation spectroscopy — •Thomas Volz — School of Mathematical and Physical Sciences, Macquarie University, Sydney, Australia

In quantum optics, the radiative quantum cascade is of fundamental importance. Two-photon cascaded emission has been instrumental for example to test Bell inequalities and generate entangled photon pairs. These experiments rely on the nonlinear nature of the underlying energy ladder, which enables the direct excitation and probing of specific single-photon transitions. Here we use exciton-polaritons to explore the cascaded emission of photons in the regime where individual transitions are not resolved. We excite a polariton quantum cascade by off-resonant laser excitation and probe the emitted luminescence using a combination of a narrow spectral filter and a Hanbury-Brown and Twiss setup for measuring the second-order autocorrelation function of the photons. The measured photon-photon correlations exhibit a strong dependence on the polariton energy and therefore on the underlying polaritonic interaction strength, with clear signatures of Feshbach resonances due to two- and three-body excitonic complexes, shedding new light on earlier observations of photon autocorrelations in resonant transmission. We not only establish photon cascade correlation spectroscopy as a highly sensitive tool to study the underlying quantum properties of novel semiconductor materials and many-body quantum phenomena. Our findings also highlight the potential of semiconductor exciton-polariton systems for generating single-photon non-linearities.