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Seminar on Quantum Information Processing and Communication

Novel quantum light sources fabricated by Molecular Beam Epitaxy (MBE)

Seminar by Professor David Ritchie, Cavendish Laboratory, University of Cambridge, UK

ABSTRACT
We have fabricated triggered sources of entangled photons based on self assembled quantum dots. These sources rely on the radiati- ve decay from a biexciton state to the ground state via an intermediate exciton state. A splitting of the exciton state due to the ani- sotropic nature of the quantum dots yields only classically correlated emission, however techniques have now been developed to tune this splitting to zero and allow the emission of entangled photons.

A second type of source required the use of MBE regrowth on patterned substrates to form a lateral n-p junction. Surface acoustic waves have been used to drive electrons through the n-p junction, these electrons recombine with holes with consequent light emissi- on. This device has been shown to emit small packets of photons at a repetition rate of 1GHz.

The development and operation of both types of source, in which the crucial elements were fabricated by MBE, will be described in the talk.


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