New Research


Diamond Quantum Spintronics

~ Control of single spin, photon, and charge at room temperature ~

Y. Suzuki, N. Mizuochi, S. Miwa, T. Shinjo, E. Tamura, H. Morishita, T. Tashima

 Recently, one of our main research topic is diamond quantum spintronics. This is mainly conducted by Assoc. Prof. N. Mizuochi. In diamond, various kind of impurities can be incorporated. Among them, a NV center is well known, which consists of Nitrogen (N) and Vacancy (V). The NV center is significantly interested in wide fields such as quantum information science, magnetometry, and biomarker. One of the reason is that the single NV center can be optically addressed and its single electron spin can be controlled and detected at room temperature.

 Recently, by utilizing the excellent properties, we expect that the NV center play a role of quantum interface among single spin, single photon and single charge. Previously, we realized the electrically driven single photon source by utilizing the NV center in diamond diode (Nat. Photon. 6, 299, 2012). This is the first realization of electrically driven single photon source at room temperature among solid state devices. Recently, we realized the electrical control of charge state of single NV- to NV0 for the first time (Phys. Rev. X, 4, 011057, 2014).

 Furthermore, we could find the condition of nearly perfect alignment of the N-V axis parallel to [111]-axis (Appl. Phys. Exp. 7, 055201, 2014). In the diamond crystal structure, the orientations of NV centers are classified according to the alignment along one of four possible crystallographic axes: [111], [11 ̅1 ̅ ],[1 ̅11 ̅ ] or [1 ̅1 ̅1]. From the analysis of optically detected magnetic resonance spectrum, it was indicated that the orientation of more than 99 % of the NV centers can be aligned along the [111]-axis by chemical vapor deposition homoepitaxial growth on (111)-diamond substrates. Our result provides increased optical readout contrast for NV multi-spin measurements. And the enhanced readout contrast enables a fourfold improvement in magnetic-field sensitivity. In addition, the realization of the perfect alignment is very important for quantum hybrid systems such as a superconducting flux qubit and the spin of the NV center.

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