We work on research and development of scalable quantum computer with spins as well as quantum interface of qubit systems between spin and superconducting or photon states. In particular, we aim to (1) establish scalable smallscale quantum system with semiconductor spins (Fig. 1) or molecular spins (Figs. 2 and 3) as qubits, and finally use it to demonstrate error correction algorithm and smallscale logical operation, and (2) establish technology for controlling quantum coupling between spin and superconducting qubits (Fig. 4) and between spin and photon qubits, and finally more sophisticate peripheral technology of smallscale quantum system, including quantum memory and quantum network.

Fig.1 Multiple spin qubit device consisting of multiple quantum dots placed between a pair of micromagnets.

Fig.2 A triplestranded metallohelicate as addressable Lloyd’s electron spinqubits. The stranded structure is based on the Xray structure analysis.

Fig.3 Resonator transients are compensated for precise spin quantum gates.

Fig.4 Future of silicon quantum computing. A silicon nuclear spin memory segment on the left is connected to the superconducting processing segment on the right.