An Efficient Singlet-Triplet Spin Qubit to Fiber Interface Assisted by a Photonic Crystal Cavity
摘要
We introduce a novel optical interface between a singlet-triplet spin qubit and a photonic qubit which would offer new prospects for future quantum communication applications. The interface is based on a 220 nm thick GaAs/AlGaAs heterostructure membrane and features a gate-defined singlet-triplet qubit, a gate-defined optically active quantum dot, a photonic crystal cavity and a bottom gold reflector. All essential components can be lithographically defined and deterministically fabricated, which greatly increases the scalability of on-chip integration. According to our FDTD simulations, the interface provides an overall coupling efficiency of 28.7% into a free space Gaussian beam, assuming an SiO2 interlayer filling the space between the reflector and the membrane. The performance can be further increased to 48.5% by undercutting this SiO2 interlayer below the photonic crystal.