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arXiv · 2403.00857

Two-colour photon correlations probe coherent vibronic contributions to electronic excitation transport under incoherent illumination

Charlie Nation·Valentina Notararigo·Hallmann Oskar Gestsson·Luca Sapienza·Alexandra Olaya-Castro
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Abstract

Identifying signatures of quantum coherent behaviour in photoactive systems that are maintained in stationary states away from thermal equilibrium is an open problem of wide interest in a variety of physical scenarios, including single photosynthetic complexes subjected to continuous incoherent illumination. Here we consider a prototype light-harvesting heterodimer exhibiting coherent and collective exciton-vibration interactions and show that the second-order frequency-filtered correlations of fluorescence photons provide insightful information on the influence of such coherent interactions for different transitions, thereby yielding fundamentally different photon-counting statistics. Furthermore, we show that coherent vibronic mechanisms strongly affect the asymmetries characteristic of time-resolved photon cross-correlations and manifest themselves in a time-dependent violation of the Cauchy-Schwarz inequality bounding cross-correlations for classically fluctuating fields. We finally discuss how such second-order correlation asymmetry establishes important connections between coherent vibronic interactions, directional exciton population transport, and violation of quantum detailed balance. Our work then indicates that measurement of two-colour photon correlation asymmetry can be an important avenue to investigate quantum behaviour of single photoactive biomolecular and chemical systems under incoherent illumination conditions.

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Charlie Nation, Valentina Notararigo, Hallmann Oskar Gestsson, Luca Sapienza, Alexandra Olaya-Castro. 2024-02-29. Two-colour photon correlations probe coherent vibronic contributions to electronic excitation transport under incoherent illumination. https://arxiv.org/abs/2403.00857

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