Silicon Vacancy Centers in Diamond for Quantum Sensing

Silicon vacancy centers (SiV), especially negatively charged SiV (SiV^-), in diamond have recently emerged as a promising platform for quantum sensing. The advantages over other well-established quantum sensors are twofold. First, their stability, excellent optical properties and long spin coherence time at cryogenic temperature extend the applicability of diamond-based quantum sensors to extreme conditions. Second, it offers the option of all-optical manipulation of its spin states, allowing the application where the use of microwaves is restricted.

In general, single, shallow and stable SiV centers with good optical and spin coherence in a diamond probe with high optical collection efficiency are essential for quantum sensing. Here, we report a robust way to prepare shallow implanted SiV^- in diamond parabolic reflectors (PR)^[1] with narrow lines. A novel optical charge stabilization method is implemented to obtain lifetime-limited, long-term spectrally stable SiV^- at 6K. Also, we demonstrate that single SiV^- among a small ensemble in a PR can be addressed with resonant excitation, expanding the range of usefulness of diamond probes. Meanwhile, photon correlation measurements upon resonant excitation reveal the population dynamics within the fine structure of SiV^-. Moreover, as neutrally charged SiV centers show promising potential in quantum sensing, we demonstrate an easy way to stabilize this charge state by hydrogen surface termination^[2] and an all-optical charge dynamic control of SiV.