A proposal for the implementation of single-qubit quantum gates based on a third order nonlinear process in integrated quantum circuits is presented.

This work presents a feasible design of an integrated photonic circuit performing as a device for single-qubit preparation and rotations through the third-order nonlinear process of difference frequency generation (DFG) and defined in the temporal mode basis. The first stage of our circuit includes the generation of heralded single photons by spontaneous four-wave mixing in a micro-ring cavity engineered for delivering a single-photon state in a unique temporal mode. The second stage comprises the implementation of DFG in a spiral waveguide with controlled dispersion properties for reaching color qubit preparation fidelity close to unity. We present the generalized rotation operator related to the DFG process, a methodology for the device design, and qubit preparation fidelity results as a function of user-accessible parameters.

We present a design for an integrated single-qubit quantum gate based on the third order nonlinear process of difference frequency generation. A theoretical model is presented for the transformation of the qubit with device-external parameters.

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