Burgarth, D.K.;
(2007)
Quantum state transfer with spin chains.
Doctoral thesis , University of London.
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Abstract
In the last few decades the idea came up that by making use of the superposition principle from Quantum Mechanics, one can process information in a new and much faster way. Hence a new field of information technology, QIT (Quantum Information Technology), has emerged. From a physics point of view it is important to find ways of implementing these new methods in real systems. One of the most basic tasks required for QIT is the ability to connect different components of a Quantum Computer by quantum wires that obey the superposition principle. Since superpositions can be very sensitive to noise this turns out to be already quite difficult. Recently, it was suggested to use chains of permanently coupled spin-1/2 particles (quantum chains) for this purpose. They have the advantage that no external control along the wire is required during the transport of information, which makes it possible to isolate the wire from sources of noise. The purpose of this thesis is to develop and investigate advanced schemes for using quantum chains as wires. We first give an introduction to basic quantum state transfer and review existing advanced schemes by other authors. We then introduce two new methods which were created as a part of this thesis. First, we show how the fidelity of transfer can be made perfect by performing measurements at the receiving end of the chain. Then we introduce a scheme which is based on performing unitary operations at the end of the chain. We generalise both methods and discuss them from the more fundamental point of view of mixing properties of a quantum channel. Finally, we study the effects of a non-Markovian environment on quantum state transfer.
| Type: | Thesis (Doctoral) |
|---|---|
| Title: | Quantum state transfer with spin chains. |
| Identifier: | PQ ETD:592653 |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Thesis digitised by Proquest |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1445333 |
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