Polarization-to-spin conversion and entanglement distribution via coherent interface with semiconductor double quantum dot*

Interfacing photonic qubits with a gate-defined spin qubit remains critical challenges in semiconductor devices. In this talk, we discuss the key properties of a coherent interface by two separate experiments, quantum state transfer, and entanglement absorption with a double quantum dot. We report polarizationto-to-spin conversion implemented with single-shot readout of a single electron spin generated in a GaAs quantum dot. The optical spin blockade effect requires in-plane magnetic field and photo-excitation associate to Zeeman-splitted light-holes, but not heavy-holes. This effect, following the optical selection rules, determines the generation efficiency depending on the photonlinear-polarization and the electron number in the dot. Secondly, we discuss the experimental progress of entanglement absorption between an entangled photon pair to a single spin and a photon. With the temporal coincidences and the conditional probabilities of the polarized photon and the electron spin correlation, we plan to detect individual entanglement transferal events.