Revisiting physics of quantum bits

Halataei, Seyyed Mohammad Hassan

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https://hdl.handle.net/2142/99318 Copy

Description

Title

Revisiting physics of quantum bits

Author(s)

Halataei, Seyyed Mohammad Hassan

Issue Date

2017-11-07

Director of Research (if dissertation) or Advisor (if thesis)

Leggett, Anthony J.

Doctoral Committee Chair(s)

Cooper, Lance

Committee Member(s)

• Weissman, Michael B.
• Bezryadin, Alexey

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Qubit
• Decoherence
• Dissipation
• Superconducting Qubit
• Flux Qubit
• Nano magnetic molecule
• Molecular qubit
• Quantum noise simulation
• oscillator bath simulation
• spin bath
• mapping
• Double well potential
• Classical noise
• Landau-Zener effect

Abstract

Advancements in the technology of quantum bits invoke more precise calculations for decoherence and dissipative effects. In this thesis, the physics of truncated two level systems is revisited and it is shown that in some systems, such as in triple-junction superconducting flux qubit, environmental noises that are usually recognized to only have dissipative effects and the trivial resultant dephasing, can also cause pure dephasing. Furthermore, it is demonstrated that, in the current domain of interest for quantum computation purposes, the effective Hamiltonian of single molecule magnets in interaction with a spin bath differs from the commonly quoted result in the literature. It is also shown that the topological effects in such problems are as small as transitional effects to higher excited states beyond the two-level picture. Finally, a simulation of the quantum noise by the classical noise and a simulation of spin bath by oscillator bath for a quantum bit as the principal system are presented.

Graduation Semester

2017-12

Type of Resource

text

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http://hdl.handle.net/2142/99318

Copyright and License Information

Copyright 2017 by Seyyed Mohammad Hassan Halataei. All rights reserved.

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