CoCoON

Over the past decade, the field of quantum computing has become a major driving force for both fundamental physics and engineering, with impressive milestones demonstrated on several competing platforms. But today, even for an expert in the field, it is still hazardous to predict which physical system will be the most successful implementation in 10 years’ time, because achieving large-scale universal operations on a quantum computer requires not only world-class engineering, but also major conceptual breakthroughs. Optical quantum computers, and in particular nanophotonic circuits, are among the leading candidates due to their high scalability and small footprint. However, implementing universal operations on scalable nanophotonic platforms requires deterministic nonlinearities at the single-photon level, and so far, no known approach has been able to implement it reliably. The CoCoON project proposes to solve this critical problem by using quantum nano-emitters efficiently coupled to a nanophotonic waveguide, a nanofiber, to mediate deterministic nonlinear interactions between photonic qubits. With its original approach, the project bridges the gap between nanophotonics (usually limited to the discrete-variable approach) and the continuous-variable regime, through the generation of non-gaussian states. In doing so, I will answer fundamental questions about the amount of nonlinearity and quantumness contained in the light-matter interaction described by the Jaynes Cummings model, and that is required to achieve scalable universal photonic quantum computing.