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Acoustic Transport of Electrons in Parallel Quantum Wires

100%

Cunningham J., Pepper M., Talyanskii V., Ritchie D.

Acta Physica Polonica A

2005

vol. 107

issue 1

38-45

Over the last few years we have developed a new method to control single-electrons by isolating and moving them through a submicron width channel formed in a GaAs/AlGaAs heterostructure using a surface acoustic wave. The acoustic wave acts to push electrons through the depleted submicron channel in packets each containing an integer number of electrons. Our primary motivation for studying this system has been to develop a new standard of dc current for metrological purposes, but our recent focus has widened to investigate the possibility of single-photon emission. Here we show new experimental results which demonstrate acoustoelectric current flow in adjacent 1D wires. These results have relevance both to the use of the system in a single-photon emission scheme, as well as in the creation of a proposed acoustoelectric quantum computer.

Control of Exciton Fine Structure Splitting in Quantum Dots

76%

Stevenson R., Young R., Atkinson P., Cooper K., Ritchie D., Shields A.

Acta Physica Polonica A

2006

vol. 110

issue 3

311-318

Quantum dots have been identified as potential sources of entangled photon pairs, essential for many applications in quantum information. However, in practice structural properties of the dots result in polarisation splitting of the emission lines, which has prevented the realisation of such a source. Here, we present two techniques developed to control the polarisation splitting in a quantum dot both irreversibly and reversibly. We find that the splitting is strongly dependent upon the emission energy, or lateral confinement, of the quantum dot. Thus by precise control of the InAs deposition thickness, it is possible to produce ensembles from which dots with zero polarisation splitting can be easily selected. Additionally, we demonstrate that by using modest in-plane magnetic fields to partially mix the bright and dark exciton states, the polarisation splitting can be reversibly tuned to zero for most dots of a certain type. Finally, we demonstrate the emission of triggered entangled photon pairs from a quantum dot with approximately zero splitting with fidelity >70%.

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2 Acta Physica Polonica A

1 2006

1 2005

2 Ritchie D.

1 Atkinson P.

1 Cooper K.

1 Cunningham J.

1 Pepper M.

1 Shields A.

1 Stevenson R.

1 Talyanskii V.

1 Young R.

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Acoustic Transport of Electrons in Parallel Quantum Wires

Control of Exciton Fine Structure Splitting in Quantum Dots