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Quantum Interference and Coherence and Electromagnetic Induced Transparency in Multilevel Atomic Systems

Naseri, Tayebeh | 2014

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 46743 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Sadighi Bonabi, Rasoul
  7. Abstract:
  8. This thesis deals with the theoretical and experimental investigation of quantum interference and coherence, and electromagnetic induced transparency (EIT) in multi-level atomic systems such as hot and cold Rb atoms, semiconductor quantum dots and wells. Optical properties of atomic media in presence of coherent laser fields and incoherent fields are studied.
    Theoretical studies verify the crucial role of atomic coherence due to quantum interference in modifying optical properties of atomic media. Suitable and efficient models based on multi-level atomic systems to investigate the optical properties and, optical bistability and multistability are proposed. The most advantages of these models in comparison with the previous models are their high efficiency and convenient controllability in the experimental realization.Electromagnetic induced grating (EIG) is known as one of the interesting applications of EIT. EIG is an optical interference phenomenon where an interference pattern is used to build a dynamic spatial diffraction grating in multi-level atomic systems. EIG can be used for the purposes of atomic/molecular velocimetry and switching of light. In this thesis new schemes for facilitating high efficient electromagnetic induced grating (35%) are proposed.Laser cooling via magneto-optical trapping method in order to produce samples of cold, trapped, Rb atoms at temperatures as low as several microkelvins is implemented experimentally. After producing cold Rb atoms, an additional challenge in this project was guiding an optical wave through atomic cloud of Rb cold atoms. We have addressed this by means of tapered optical fibers of submicron diameters. A significant fraction of the optical mode guided by such a fiber propagates as an evanescent field. In this way, if the fiber is placed inside a cloud of cold atoms, the atoms would have easy access to the guided light, thus accelerating strong coupling between these two quantum systems. Interfacing quantum information between light and atoms also allows us to realize nonlinear optical interaction at single-photon energy levels in order to observe EIT. This technology can open up a wide range of perspectives in quantum optical information processing
  9. Keywords:
  10. Quantum Interference ; Optical Bistability ; Electromagnetical Induced Transparency ; Multilevel Atomic Systems ; Optical Switching

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