Abstract: Interaction between individual photons forms the foundation of gate-based optical quantum computing among other quantum-enabled technologies. Quantum emitter-mediated photon interactions are fundamentally constrained by stringent operation conditions and the available photon wavelength and bandwidth, posing difficulty in upscaling and practical applications. It is a long-standing goal to realize interactions between individual photons using the more engineerable bulk optical nonlinearity, such as chi2 and chi3. I will describe the first observation of photon-photon interaction mediated by a virtual photon in an integrated photonic circuit with a substantial chi2 nonlinearity and the resulting quantum correlations of transported photons including photon repulsion and attraction. These results represent a significant leap in nonlinear optics and quantum photonics, transcending the longtime paradigm of parametric nonlinear processes and paving the way towards strongly-interacting photons in bulk nonlinear systems. Moreover, I will talk about using such integrated photonic platform with extreme nonlinearity for nonlinearity-enabled quantum network protocols.
Biography: Kejie Fang received BS in physics from Peking University and PhD in physics from Stanford University, advised by Shanhui Fan. He then worked in Caltech as a postdoctoral researcher in Oskar Painter’s group. He is now an Assistant Professor and Y.T. Lo Faculty Fellow in the Department of Electrical and Computer Engineering and holds affiliation in the Department of Physics. His research focus is in quantum photonics and devices for quantum information processing and networking. He has received NSF CAREER Award and was selected for DARPA Young Faculty Award.