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# James March

I am studying for a PhD under the supervision of Dr Gavin Morley. I began studying for my PhD in October 2018, after completing the Physics MSci course at the University of Nottingham.

My project is entitled "Towards Placing a Nanodiamond Containing a Negatively Charged Nitrogen Vacancy Defect in a Mesoscopic Superposition". It has been proposed that a levitated nanodiamond containing a negatively charged nitrogen vacancy (NV-) defect could be used to attempt to place a relatively massive object (∼10-15 kg) in a spatial superposition. The proposals exploit the favourable spin properties of the NV- defect, such as initialisation via optical pumping and manipulation using microwaves. The motion of the centre of mass of the nanodiamond is coupled to the spin of the defect via a magnetic field gradient. After initialising the spin of the defect into a superposition of the form $\frac{\ket{\beta}(\ket{|1>} + \ket{|-1>})}{\sqrt{2}}$, the magnetic field gradient will act to separate the |$\ket{\pm1}>$ components, placing the centre of mass state in a spatial superposition.

We are currently setting up a magnetic trap that, due to the diamagnetism of diamond, can stably levitate nanodiamonds containing NV- defects under high vacuum. We will monitor the motion of the diamond using interferometric balanced detection, and will be looking to employ feedback cooling to cool the oscillatory motion of the diamond. Longer term aims are to detect fluorescence from the NV- defect contained within the levitated nanodiamond, and to detect optically detected magnetic resonance (ODMR).

james.march@warwick.ac.uk

Warwick Diamond Research Group
Department of Physics
University of Warwick
Gibbet Hill Road
Coventry
CV4 7AL