Charge State Control of Single Nitrogen-Vacancy Centers in Diamond

Quantum information in which spin is used as a source of non-classical computation and communication, attracts considerable interest.A long spin coherence (T 2 ) are required toward quantum processing.In addition, small spectral diffusion of single photon for realization of quantum cryptography and building quantum network is needed.The nitrogen-vacancy center (NV) in diamond have long T 2 (up to several milliseconds at room temperature) and become single-photon emitter.Now a days, optically induced charge state interconversion on NV significantly extend T 2 of proximal nuclear spin owing to hyperfine interaction is weaken by motion narrowing.Theory predicts that T 2 exceeding 1 min with preventing heating of diamond due to high laser power excitation.This demonstration show potential of charge state and its non-optical control for spin properties of the NV center.Despite optical illumination is essential for NV to initialize and readout spin, optically induced charge state interconversion causes error in quantum control and spectral diffusion in emitted single photons.In this study, charge state of single NV centers are deterministically controlled by non-optical method.Charge state of single NVs formed in the intrinsic layer of p-in diode are modulated by current injection.Transition rate and its dependence on current is revealed.Recent controllable direction of charge state is limited; however this non-optical charge state control on spin-active negatively charged state (NV -) open the new way to spin related experiments.This study also realize purely populated charge state on the single NVs in phosphorus doped n-type diamond.Charge state is perfectly stabilized into NV -state even under optical illumination (1 µW, 593 nm).After NV - charge state is disturbed by strong laser excitation, state recovered to NV -state under dark condition.This result pave the way to the single spin manipulation in high efficiency and suppress spectral diffusion of single emitted photons. 概要この NV 中心は光励起下(波長: 593 nm, 強度: 1 µW) においても電荷状態が変化しない。また強い光励起によって電荷状態の変化が引き起こ されても、その後 0.28 ms -1 のレートで完全に NV -へと回復することがわかった。この 成果は単一スピン操作の精度、並びに単一光子のスペクトルの安定性向上に繋がる。 Contents 5.2.Raster scan images and fluorescence time traces . . . . . . . . . . . . . .5.3.Single-shot charge-state measurements . . . . . . . . . . . . . . . . . . .5.4.Recombination/recharge rate in the dark condition . . . . . . . . . . . .5.5.Charge-state population and recombination rate under laser excitation .5.6.ODMR and spin coherence measurements . . . . . . . . . . . . . . . . .