(a) Superconductor-diamond hybrid system. (b) Microwave spectrum of a superconducting flux quibt.
(c) Vacuum Rabi oscillation between a flux qubit and a spin ensemble.


Coherent Coupling of a Gap-Tunable flux Qubit to an Electron Spin Ensemble in Diamond

A superconductor-diamond hybrid system has attracted considerable interest as the electron spin trapped at a nitrogen-vacancy (NV) center in diamond has the potential to be a quantum memory for a superconducting qubit. In this research we have achieved strong coupling between a gap-tunable flux qubit and an NV spin ensemble. Furthermore we also observed the coherent exchange of a single quantum of energy between them. This is the first step towards the realization of a long-lived quantum memory and hybrid devices coupling microwave and optical systems. (Page 33)