Spingineering : quantum control in the presence of relaxation
Name
50783904-MIT.pdf
Description
Full printable version
Size
6.87 MB
Format
Adobe PDF
Checksum (MD5)
9d698f4f549f5c626f1e276dce23e287
Author(s)
Recht, Benjamin Harris, 1978-
Advisor(s)
Neil Gershenfeld.
Alternative Title
Quantum control in the presence of relaxation
Date Issued
2002
Publisher
Massachusetts Institute of Technology
Abstract
For certain problems quantum resources can exponentially increase computing power, but these quantum resources are very fragile in practice. When a quantum system interacts with an external environment, it undergoes decoherence - the loss of quantum correlation - and relaxation - the loss of energy - and eventually all of the quantum information is lost. Here we show a general principle of using unitary operators to suppress relaxation processes. Unitary operations do not cool a quantum system and seem an unlikely candidate for preventing irreversible thermodynamic heating processes, but surprisingly most decoherence processes can be corrected or ameliorated using open loop control with unitary controllers. We examine the different mechanisms of decoherence and relaxation on simple spin systems and discuss when the modes can be corrected. We show experimentally the feasibility of our correction schemes using nuclear magnetic resonance. We also demonstrate control of the nuclear spins over long time scales. Finally, we discuss the applications of unitary correction to higher dimensional systems and the potential applications to quantum information processing.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2002.
Includes bibliographical references (leaves 77-80).
Subjects
Architecture. Program In Media Arts and Sciences.
MIT Department
Program in Media Arts and Sciences (Massachusetts Institute of Technology)
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