ECCS/EPMD: Single-photon quantum information processing with nonlinear photonic integrated circuits

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

Creation and control of quantum correlations and entanglement between photons is critical to quantum information processing and particularly for quantum network protocols, including two-photon quantum logic and efficient entanglement swapping, which requires photon-photon interaction. Strong photon-photon interaction is typically achieved via highly nonlinear systems, such as cavity-quantum electrodynamics (QED) systems consisting of atoms coupled with high-Q optical cavities, or by measurement-based, post-selection methods. Despite successful demonstrations, these approaches involving complicated setups and/or stringent experimental conditions are arguably difficult for more complex and upscaled quantum information tasks. It is thus highly desirable to realize photon-photon interaction based on bulk optical nonlinearities without resorting to quantum emitters. However, because of the weak bulk optical nonlinearity, quantum photonic systems, including both bulk crystals and integrated photonic circuits, are almost exclusively operated in the parametric regime for applications such as heralded single-photon sources and continuous-variable quantum information tasks (except for measurement-based protocols which are typically probabilistic). It remains an outstanding challenge to realize single-photon nonlinearity with bulk materials and substantial photon-photon correlations that are useful for quantum information applications. In this program, we will tackle this fundamental challenge using an approach combining a state-of-the-art integrated quantum photonic platform and innovative quantum optical methods that will lead to critical quantum optical protocols, including quantum non-demolition measurement of photons—a capability that could revolutionize all of optical quantum information processing. We will realize few-photon quantum coherence all-optically, capitalizing on our recently developed integrated quantum photonic platform with a record-high optical nonlinearity. Our approach, based on quantum interference via waveguide-coupled nonlinear optical cavities, will enable generation and manipulation of few-photon quantum correlations in the integrated photonic system by controlling its linear response. This will allow us to demonstrate several critical quantum optical protocols including quantum non-demolition measurement of photons and synchronous entanglement swapping with high fidelity. The outcome of this program will have broader impacts in harnessing quantum coherence, enhancing photonic quantum information processing, and paving the way towards repeater-enabled quantum networks. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.