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Symmetry and Control in Spin-Based Quantum Computing

Title: Symmetry and Control in Spin-Based Quantum Computing.
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Name(s): Stepanenko, Dimitrije, author
Bonesteel, Nicholas E., professor directing thesis
Mio, Washington, outside committee member
Dobrosavljevi´c, Vladimir, committee member
Molnar, Stephan von, committee member
Riley, Mark, committee member
Department of Physics, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: Text
Issuance: monographic
Date Issued: 2005
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: A promising proposal for quantum computation, due to Loss and DiVincenzo, is based on using electron spins in quantum dots as qubits - two-level systems which are the quantum analogues of classical bits. Two-qubit operations (quantum gates) are then carried out by switching on and off the exchange interaction between neighboring spins (i.e. "pulsing" the interaction). This thesis presents a study of the effect of anisotropic corrections to the exchange interaction due to spin-orbit coupling on this scheme. It is shown that time-symmetric pulsing automatically eliminates some undesirable terms in the resulting quantum gates, and well-chosen pulse shapes can produce an effectively isotropic exchange gate which can be used for universal quantum computation. Deviations from perfect time-symmetric pulsing are then studied in the context of a microscopic model of GaAs quantum dots. A new proposal for universal quantum computation which uses control of anisotropic corrections is then presented. In this proposal, the number of pulses required to carry out quantum gates scales as the inverse of a dimensionless measure of the degree of control. The size of this dimensionless figure-of-merit" depends on (i) variation of anisotropy with interdot distance, and (ii) restrictions on the pulse duration due to decoherence for slow pulses and nonadiabatic transitions for fast pulses. Taking these constraints into account, the figure-of-merit is estimated for GaAs quantum dots and shown to be large enough to be useful forquantum computation.
Identifier: FSU_migr_etd-0378 (IID)
Submitted Note: A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Degree Awarded: Degree Awarded: Summer Semester, 2005.
Date of Defense: Date of Defense: June 10, 2005.
Keywords: Spin-orbit coupling, Quantum dots, Quantum computing
Bibliography Note: Includes bibliographical references.
Advisory committee: Nicholas E. Bonesteel, Professor Directing Thesis; Washington Mio, Outside Committee Member; Vladimir Dobrosavljevi´c, Committee Member; Stephan von Molnar, Committee Member; Mark Riley, Committee Member.
Subject(s): Physics
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_migr_etd-0378
Owner Institution: FSU

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Stepanenko, D. (2005). Symmetry and Control in Spin-Based Quantum Computing. Retrieved from http://purl.flvc.org/fsu/fd/FSU_migr_etd-0378