Condensed Matter Physics Seminar

Axel Kuhn, University of Oxford

Friday 17 May 2013, 1500-1600
C1 Physics Building

Qubits, Qutrits and Ququads in Single Photons

The ability of encoding arbitrary information in elementary quantum systems is the key to a novel approach to computing based on quantum mechanics. Particular attention has been paid toward the field of linear optics quantum computing (LOQC) which in principle is a scalable, albeit often restricted by the spontaneous nature of parametric down-conversion sources. Here, I will show that single photons emitted on demand from a single atom into an optical cavity can be used to get past those limits. With a coherence time greater than 500 ns, a subdivision of photons into d time bins of arbitrary amplitudes and phases has been achieved, which we use for encoding arbitrary qu-d-its in one single photon. The fidelity of the quantum state preparation is verified in time-resolved quantum-homodyne measurements, and the photons are used to operate elementary quantum gates in integrated photonic circuits.

P.B.R. Nisbet-Jones et al, New J. Phys. 15 (2013) 053007