Browsing by Author "Dinani, Hossein T."

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    Adaptive estimation of a time-varying phase with coherent states: Smoothing can give an unbounded improvement over filtering
    (2018) Laverick, Kiarn T.; Wiseman, Howard M.; Dinani, Hossein T.; Berry, Dominic W.
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    Probabilistic magnetometry with a two-spin system in diamond
    (2021) Coto, Raul; Dinani, Hossein T.; Norambuena, Ariel; Chen, Mo; Maze, Jeronimo R.
    Solid-state magnetometers like the nitrogen-vacancy (NV) center in diamond have been of paramount importance for the development of quantum sensing with nanoscale spatial resolution. The underlying protocol is a Ramsey sequence, that imprints an external static magnetic field into the phase of the quantum sensor, which is subsequently read out. In this theoretical work we propose a sensing scheme that harnesses the hyperfine coupling between the NV center and a nearby nuclear spin to set a post-selection protocol. We show that concentrating valuable sensing information into a single successful measurement yields an improvement in sensitivity over Ramsey in the range of short transverse relaxation times. By considering realistic experimental conditions, we found that the detection of weak magnetic fields in the mu T range can be achieved with a sensitivity of few tens of nTHz(-1/2) at cryogenic temperature (4 K), and mu THz(-1/2) at room temperature.
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    Probing Charge Dynamics in Diamond with an Individual Color Center
    (2021) Gardill, Aedan; Kemeny, Ishita; Cambria, Matthew C.; Li, Yanfei; Dinani, Hossein T.; Norambuena, Ariel; Maze, Jeronimo R.; Lordi, Vincenzo; Kolkowitz, Shimon
    Control over the charge states of color centers in solids is necessary to fully utilize them in quantum technologies. However, the microscopic charge dynamics of deep defects in wide-band-gap semiconductors are complex, and much remains unknown. We utilize a single-shot charge-state readout of an individual nitrogen-vacancy (NV) center to probe the charge dynamics of the surrounding defects in diamond. We show that the NV center charge state can be converted through the capture of holes produced by optical illumination of defects many micrometers away. With this method, we study the optical charge conversion of silicon-vacancy (SiV) centers and provide evidence that the dark state of the SiV center under optical illumination is SiV2-. These measurements illustrate that charge carrier generation, transport, and capture are important considerations in the design and implementation of quantum devices with color centers and provide a novel way to probe and control charge dynamics in diamond.
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    Temperature-Dependent Photophysics of Single NV Centers in Diamond
    (2023) Happacher, Jodok; Bocquel, Juanita; Dinani, Hossein T.; Tschudin, Marta A.; Reiser, Patrick; Broadway, David A.; Maze, Jeronimo R.; Maletinsky, Patrick
    We present a comprehensive study of the temperature- and magnetic-field-dependent photolumine-scence (PL) of individual NV centers in diamond, spanning the temperature-range from cryogenic to ambient conditions. We directly observe the emergence of the NV's room-temperature effective excited-state structure and provide a clear explanation for a previously poorly understood broad quenching of NV PL at intermediate temperatures around 50 K, as well as the subsequent revival of NV PL. We develop a model based on two-phonon orbital averaging that quantitatively explains all of our findings, including the strong impact that strain has on the temperature dependence of the NV's PL. These results complete our understanding of orbital averaging in the NV excited state and have significant implications for the fundamental understanding of the NV center and its applications in quantum sensing.