Efficient two-photon absorption by photonic-dimer coherent states

Recently, a new type of quantum many-photon state, coherent states of photonic dimers, has been introduced, where the fundamental building blocks are two-photon bound states instead of individual photons as in conventional laser light. In this talk, we generalize the concept of photonic dimers to include states where the two photons have distinct frequencies, termed two-color dimers. We discuss the basic properties of two-color dimers and present a generation scheme for two-color dimer coherent states. Our findings show that these dimer coherent states outperform laser light in the two-photon absorption process due to their intrinsic photon-photon correlations. We also identify the parameter ranges where dimer coherent states surpass laser light, highlighting their potential for enhancing two-photon excitation efficiency in various applications, such as deep tissue imaging in two-photon fluorescence microscopy.