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Angelo Frangeskou

I am undertaking a PhD at the University of Warwick under the supervision of Gavin Morley in the EPR research group, having completed an MSc in Physics by research at Royal Holloway, Uni. of London. I am investigating single electron spins in optically trapped nanodiamonds.

Nitrogen Vacancy centers (NV centers) in diamond have been shown to be excellent candidates as quantum bits (qubits), with long coherence lifetimes exceeding milliseconds at room temperature; the NV center is ideal for this purpose becuase it has a single electron spin that can be manipulated using a magnetic resonance technique known as electron paramagnetic resonance (EPR), where microwaves are used to resonantly excite electron spins in magnetic fields. One of the key advantages of the NV centre is that the spin state can then be read out optically, facilitating the control of a single electron spin, as opposed to large ensembles of spins in most EPR and NMR experiments.

nvenergylevels

For this project, an experiment is being built including 2.87 GHz excitation for diamonds held in an optical trap; this frequency is chosen because the negatively charged nitrogen vacancy (NV) consists of a spin triplet with the |0> state separated from the degenerate |±1> states by a zero-field splitting of 2.88 GHz. An inhomogeneous magnetic field will then be used to couple the center-of-mass motion of the levitated diamond bead to the NV spin, as a microwave pulse will excite the spin into a superposition of the |+1> and |−1> states, where each experience a different force from the magnetic field. An angle between the vertical and the z-axis of the experiment will place the |+1> and |−1> states in different gravitational potentials, leading to spatially separated center-of-mass states of the levitated diamond bead. A successful implementation of this proposal will therefore demonstrate spatial superposition of a mesoscopic object (the diamonds are 100-1000nm in diameter), potentially revealing new information about the crossover of classical and quantum physics, and may present a scheme for coupling multiple NV spins.

You can see my publications here, and read more about the project here.

I am also a demonstrator for the 2nd year UG electronics course, where students make a regulated DC supply, and the 1st year UG Electronics Workshop.

Landscape

Past:

2012-2013: Msc, Physics by Research, Royal Holloway, Uni. of London/ National Physical Laboratory

Studied quantum dot devices as detectors and sources of THz radiation

2009-2012: BSc, Physics at Royal Holloway, Uni. of London

My final year project was the observation of quantum interference effects in mesoscopic rings, like the Aharonov-Bohm effect