We are advancing the frontier of quantum measurement science by exploring the unique properties of entangled photons interacting with fluorescent proteins (FPs) and other fluorophores used in cellular imaging. For example, time-energy entanglement can significantly enhance nonlinear light-matter interactions. Entangled two-photon absorption follows linear rather than the classical quadratic intensity dependence and can be observed at much lower photon fluxes than two-photon absorption in conventional multiphoton microscopy.
We are exploring the fundamental quantum optics underlying the tantalizing possibility of bioimaging with very low photon fluxes. Development of imaging reagents with large cross-sections for interaction with entangled photons and understanding the mechanism of light-matter interaction is a prerequisite. Quantum-enhanced bioimaging may present new modes of spatial and spectral selectivity that could benefit applications in functional imaging. For example, theory predicts that absorption cross-sections are sensitive to quantum light parameters that can be tuned to achieve two-photon transparency. Development of these capabilities may open the way to fascinating possibilities for highly multiplexed multiphoton bioimaging.