Hybrid Quantum Systems with Spins in Diamond Crystals and Superconducting Circuits

Robert Amsüss, Shiro Saito, W. J. Munro

Kouichi Semba

蔭浦 泰資, 89257, Taisuke Kageura

Yingqiu Mao, Ming Gong, Kae Nemoto +2 more

Hybrid quantum systems aim at combining the advantages of different physical systems and producing innovative quantum devices. In particular, the hybrid combination of superconducting circuits and spins in solid-state crystals is a versatile platform to explore many quantum electrodynamics problems. Recently, the remote coupling of nitrogen-vacancy center spins in diamond via a superconducting bus was demonstrated. However, a rigorous experimental test of the quantum nature of this hybrid system and, in particular, entanglement is still missing. We review the theoretical ideas to generate and detect entanglement and present our own scheme to achieve this.

Kouichi Semba, Fumiki Yoshihara, Jan Johansson +6 more

Yuimaru Kubo, Cécile Grèzes, Andreas Dewes +15 more

We report the experimental realization of a hybrid quantum circuit combining a superconducting qubit and an ensemble of electronic spins. The qubit, of the transmon type, is coherently coupled to the spin ensemble consisting of nitrogen-vacancy centers in a diamond crystal via a frequency-tunable superconducting resonator acting as a quantum bus. Using this circuit, we prepare a superposition of the qubit states that we store into collective excitations of the spin ensemble and retrieve back into the qubit later on. These results constitute a proof of concept of spin-ensemble based quantum memory for superconducting qubits.