Preparing And Measuring Single Spins In Diamond At Room Temperature

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Doctor of Philosophy (PhD)
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Physics & Astronomy
NV Center
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Quantum Sensing
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Hopper, David Allen

A functioning qubit must be able to be initialized and measured. The fidelity of these operations is essential for all quantum applications, including quantum sensing, communication, and computation. The diamond nitrogen-vacancy (NV) center is a point defect in the lattice with an optical interface to a coherent ground-state spin, which makes the NV center one of the few spin qubits operable at room temperature. While the NV center spin state can be initialized and read out optically, the fidelity of these operations are far from perfect due to the charge and orbital dynamics. In typical conditions, the NV center is in the proper charge state 75% of the time, and measuring the spin state results in a non-zero signal only 1% of the time. These inefficient mechanisms make many measurements practically intractable. This thesis focuses on improving the preparation and measurement fidelities of NV centers through precise all-optical control of the charge, orbital, and spin dynamics. I first discuss an improved spin readout mechanism which relies on spin-to-charge conversion (SCC) and discuss the potential for single-shot spin readout. Following, I present how charge readout and SCC can be implemented in ensembles of NV centers within nanodiamonds and demonstrate that it provides improvements for spin-relaxometry studies. Finally, I develop a method for initializing a single NV center's charge state with real-time control and show that this capability improves spin readout performance for sensing. To conclude, I discuss how these improved initialization and readout capabilities can be applied to detecting and controlling coupled nuclear spins in the diamond lattice and consider other applications of real-time control.

Lee C. Bassett
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