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Towards Single Electron Interferometry

Johnson, N; (2017) Towards Single Electron Interferometry. Doctoral thesis , UCL (University College London). Green open access

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Abstract

There have been many studies and suggested technological applications using the two dimensional electron system in the GaAs/AlGaAs heterostructure. These have mostly focused on the behaviour of electrons propagating at or close to the Fermi Energy. More recently, one such application of this two dimensional system is for an electron pump, which isolates electrons from the two dimensional electron gas and pumps them individually at energies typically 100 meV above the Fermi energy, using surface gates to create a dynamic quantum dot. This energy regime had been previously unobtainable. We can utilise the high accuracy output of the pump - consistency that each pumped electron has the same properties, to study fundamental single particle physics, and work towards technological schemes, at this high energy. In this work we set out to continue and extend the previous work in this fi eld. We present new measurements that detail an electron detector barrier that we can use both as a sampling oscilloscope, with a bandwidth approaching 100 GHz, or to measure the wavepacket properties of electrons, including their energy and time of arrival with high resolution. After developing and establishing the electron detector, we detail a series of experiments that utilise it to measure the electron velocity, scattering mechanisms and wavepacket size. We show this work maps consistently to theory, and further, we begin to demonstrate control of the electron wavepacket, with the possibility that this hot electron system could have future technological applications. This is all put together in the construction of an interferometer, which seeks to complete our understanding of electrons in this system by measuring coherence of the wavefunction, a key step to demonstrating construction of a prescribed state.

Type: Thesis (Doctoral)
Title: Towards Single Electron Interferometry
Event: UCL
Open access status: An open access version is available from UCL Discovery
Language: English
Keywords: Experimental quantum mechanics, solid state physics, electronics, electron pump, semiconductor physics
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng
URI: http://discovery.ucl.ac.uk/id/eprint/1569542
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