Observation of dark states in a superconductor diamond quantum hybrid system.
The hybridization of distinct quantum systems has opened new avenues to exploit the best properties of these individual systems. Superconducting circuits and electron spin ensembles are one such example. Strong coupling and the coherent transfer and storage of quantum information has been achieved with nitrogen vacancy centres in diamond. Recently, we have observed a remarkably sharp resonance (~1 MHz) at 2.878 GHz in the spectrum of flux qubit negatively charged nitrogen vacancy diamond hybrid quantum system under zero external magnetic field. This width is much narrower than that of both the flux qubit and spin ensemble. Here we show that this resonance is evidence of a collective dark state in the ensemble, which is coherently driven by the superposition of clockwise and counter-clockwise macroscopic persistent supercurrents flowing in the flux qubit. The collective dark state is a unique physical system and could provide a long-lived quantum memory.
1] NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan [2].
Xiaobo
X
Zhu
NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
Yuichiro
Y
Matsuzaki
1] NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan [2] Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, 1020 Vienna, Austria.
Robert
R
Amsüss
NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
Kosuke
K
Kakuyanagi
Graduate School of Engineering Science, Osaka University, 1-3 Machikane-yama, Toyonaka, Osaka 560-8531, Japan.
Takaaki
T
Shimo-Oka
Graduate School of Engineering Science, Osaka University, 1-3 Machikane-yama, Toyonaka, Osaka 560-8531, Japan.
Norikazu
N
Mizuochi
National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan.
Kae
K
Nemoto
1] NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan [2] National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan [3].
Kouichi
K
Semba
NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
William J
WJ
Munro
NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
Shiro
S
Saito