Coherent generation of nonclassical light on chip via detuned photon blockade

The on-chip generation of nonclassical states of light is a key requirement for future optical quantum hardware. In solid-state cavity quantum electrodynamics, such nonclassical light can be generated from self-assembled quantum dots strongly coupled to photonic crystal cavities. Their anharmonic strong light-matter interaction results in large optical nonlinearities at the single photon level, where the admission of a single photon into the cavity may enhance (photon tunneling) or diminish (photon blockade) the probability for a second photon to enter the cavity. Here, we demonstrate that detuning the cavity and quantum-dot resonances enables the generation of high-purity nonclassical light from strongly coupled systems. For specific detunings we show that not only the purity but also the efficiency of single-photon generation increases significantly, making high-quality single-photon generation by photon blockade possible with current state-of-the-art samplesWe gratefully acknowledge financial support from the Air Force Office of Scientific Research, MURI Center for Multifunctional Light-Matter Interfaces Based on Atoms and Solids (Grant No. FA9550-12-1-0025) and support from the Army Research Office (Grant No. W911NF1310309). K. M. acknowledges financial support from the Alexander von Humboldt Foundation. K. G. L. acknowledges financial support from the Swiss National Science Foundation. K. A. F. acknowledges support through a Lu Stanford Graduate Fellowship. Y. A. K. acknowledges support through a Stanford Graduate Fellowship and from the Department of Defense through a National Defense Science and Engineering Graduate Fellowship. F. P. L. acknowledges support from the ERC Grant POLAFLO