Nanophotonic Chip-Based Approach to Quantum Imaging by Photon Addition

A key objective for quantum nanophotonics is to develop building blocks for a chip-based single photon sources, optical transduction and gating, and on-chip single photon detection. Performing all these functions on a single chip is very challenging but has potential for development of new integrated nanophotonics systems for quantum imaging, sensing and computation. We are developing waveguide-integrated single photon sources as part of a system capable of ‘photon addition’ of single photons to a weak thermal input light source. In photon addition, one or more photons are coherently added via stimulated emission to a weak thermal light signal to enhance the signal-to-noise ratio (SNR). This quantum approach for sensing of low photon count (1-5 photons) signals overcomes the classical SNR limit posed by current optical amplifiers and has potential to surpass current limitations for photon addition based on systems of discrete optical components by enabling the first system featuring a loss-resilient chip integration design. Importantly, this system represents a pathway towards deterministic addition of more than one photon to generate highly nonclassical photon states via sequential photon addition. Our approach to photon addition employs on-chip single photon generation by bright, homogeneously broadened, spectrally tunable color center single photon sources in hexagonal boron nitride (hBN), operating above 4K. By integration of an hBN single photon source into a single-mode silicon nitride waveguide and using a microring resonator to provide a mechanism for spectrally filtering pump light from the weak thermal light signal, we to aim to achieve a fully integrated photon addition system, featuring on-chip detection using waveguide-integrated superconducting nanowire detectors.