Spin Measurement of Negatively-Charged Defects in DiamondMichael Hanks, PhD student, NII
Abstract:
Quantum information processing technologies appear to be on the cusp of scalable, fault-tolerant
implementation. To reach that goal, in this era of limited (and costly) resources, both our selection of
the underlying physical hardware and our control methods must be tailored to maximise benchmark
quantities such as operational fidelity.
In this presentation I consider projective spin measurements on three distinct systems: The
negatively-charged nitrogen- [1], silicon- [2], and germanium-vacancy [3] centers in diamond. The
measurement scheme adopted exploits a dipole-induced transparency in a coupled optical cavity. In
this way, the path of an incident photon is entangled with the electronic state of the center, and the
expected fidelity between the inferred (pure) and actual (mixed) electronic states becomes the figureof merit.
For the nitrogen-vacancy center, these results [4] build on earlier work [5,6] by considering a more
complete energy level structure, and by allowing for the effects of state decay and consequent revival
between measurement rounds. For the silicon- and germanium-vacancy centers, to the best of myknowledge this is the first time these quantities have been estimated, prior work achieving
measurement via pumped (and perhaps Purcell-enhanced) fluorescence (e.g. [7,8]). I also discuss theimpacts of photon bandwidth on pulse times and cavity decay rates, and provide a comparison between
single-photon and coherent-light sources.

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[4] Hanks, M., Trupke, M., Schmiedmayer, J., Munro, W. J., & Nemoto, K. (2017). High-fidelity spinmeasurement on the nitrogen-vacancy center. New Journal of Physics, 19(10), 103002.
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(2014). All-optical initialization, readout, and coherent preparation of single silicon-vacancy spins indiamond. Physical review letters, 113(26), 263602.
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