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Title: Controlled entanglement dynamics in open quantum systems
Researcher: Goyal, Sandeep K
Guide(s): Ghosh, Sibasish
Keywords: open quantum system
Quantum trajectories
Non-Markovian Dynamics
Upload Date: 24-Sep-2012
University: Homi Bhabha National Institute
Completed Date: February 15, 2012
Abstract: The study of entanglement has gained prominence in recent years due to the advent of fields such as Quantum Optics and Quantum Information Theory ? advances that have harnessed such counter-intuitive quantum phenomena into elements of everyday life, improving it in the process. Ideal quantum systems, ?closed? to the outside world, remain quantum forever and thus manage to retain entanglement. Real quantum systems, however, are ?open? to the environment and are therefore susceptible to the phenomenon of decoherence. The resultant loss of entanglement is a major hindrance to the effectiveness of quantum information tasks. In this thesis we have studied the evolution of entanglement in various types of open quantum systems (OQS) coupled in various ways to local baths. We have also studied existing ways and means of controlling the decay of entanglement and have proposed a new method of doing so. We have studied the evolution of entanglement in OQS undergoing Markovian dynamics by using the Lindblad master equation as well as the method of quantum trajectories. We have analyzed the onset of the phenomenon of entanglement sudden death in finite as well as infinite dimensional OQS, connected either locally to a thermal bath or its squeezed variant, or via a quantum non-demolition-type (QND-type) interaction to a local thermal bath. We have found that the QND-type system-bath interaction works best to conserve entanglement in finite dimensional systems, whereas a squeezed thermal bath causes entanglement sudden death even at zero temperature. We have also studied some well-known methods of controlling decoherence in open systems with respect to their ability of preserving entanglement. Some of these procedures include coupling the system to a thermal bath of photonic crystals where the photonic band gap suppresses decoherence, modulation of the systembath frequency in an attempt to contain decoherence, using the method of resonance fluorescence.
Pagination: 175p.
Appears in Departments:Department of Mathematical Sciences

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01_title.pdfAttached File89.86 kBAdobe PDFView/Open
02_certificate.pdf35.14 kBAdobe PDFView/Open
03_declaration.pdf25.75 kBAdobe PDFView/Open
04_acknowledgements.pdf41.02 kBAdobe PDFView/Open
05_abstract.pdf68.1 kBAdobe PDFView/Open
06_contents.pdf67.75 kBAdobe PDFView/Open
07_list of figures.pdf92.06 kBAdobe PDFView/Open
08_list of tables.pdf30.41 kBAdobe PDFView/Open
09_chapter 1.pdf82.99 kBAdobe PDFView/Open
10_chapter 2.pdf234.33 kBAdobe PDFView/Open
11_chapter 4.pdf211.12 kBAdobe PDFView/Open
12_chapter 5.pdf114.55 kBAdobe PDFView/Open
13_chapter 6.pdf154.81 kBAdobe PDFView/Open
14_chapter 7.pdf215.83 kBAdobe PDFView/Open
15_chapter 8.pdf222.31 kBAdobe PDFView/Open
16_chapter 9.pdf167.66 kBAdobe PDFView/Open
17_chapter 10.pdf1.06 MBAdobe PDFView/Open
18_chapter 11.pdf208.23 kBAdobe PDFView/Open
19_chapter 12.pdf97.64 kBAdobe PDFView/Open
20_bibliography.pdf124.78 kBAdobe PDFView/Open
21_summary.pdf59.69 kBAdobe PDFView/Open

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