Electrical Control for Extending the Ramsey Spin Coherence Time of Ion-Implanted Nitrogen-Vacancy Centers in Diamond

The extension of spin coherence times is a crucial issue for quantum information and quantum sensing. In solid-state systems, suppressing noise through various techniques has been demonstrated. On the other hand, an electrical control for suppression is important toward individual controls of on-chip quantum-information devices. Here, we show electrical control for extension of the spin coherence times of 40-nm-deep ion-implanted single-nitrogen-vacancy center spins in diamond by suppressing magnetic noise. We apply 120 V dc across two contacts spaced by 10 mu m. The spin coherence times, estimated from a free-induction decay and a Hahn-echo decay, are increased up to about 10 times (reaching 10 mu s) and 1.4 times (reaching 150 mu s), respectively. From the quantitative analysis, the dominant decoherence source, depending on the applied static electric field, is elucidated. Electrical control for extension can deliver a sensitivity enhancement to the dc sensing of temperature, pressure, and electric (but not magnetic) fields, opening up an alternative technique in solid-state quantum-information devices.