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dc.contributor.advisorLeonid S. Levitov.en_US
dc.contributor.authorOktel, Mehmet Özgür, 1974-en_US
dc.contributor.otherMassachusetts Institute of Technology. Dept. of Physics.en_US
dc.date.accessioned2005-08-23T18:49:25Z
dc.date.available2005-08-23T18:49:25Z
dc.date.copyright2001en_US
dc.date.issued2001en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/8276
dc.descriptionThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2001.en_US
dc.descriptionIncludes bibliographical references (leaves 93-96).en_US
dc.description.abstractIn this thesis, we study the effects of interparticle interactions on the optical spectrum of cold gases. We first consider homogenous gas in the weak excitation regime and find that the optical spectrum of a system of Bosons is highly sensitive to interactions. We find that optical excitations, at temperatures low enough for the thermal de Broglie wavelength to be larger than the scattering length, become collective modes. We study collective affects in the optical spectrum both above and below Bose-Einstein condensation, and show that the spectrum acquires a doublet structure when the condensate forms. We present a detailed theory of spectral shift and an estimate of some of the broadening effects. We derive a sum rule for the average frequency shift of an optical spectrum and investigate the basic conservation laws and symmetries of the system lying at the basis of this sum rule. We also compare the sum rule for the optical spectrum with the f-sum rule for the density-density correlation function. Finally we derive a transport equation for the optical modes in a dilute Bose system, which allows us to study the non-linear response to the excitation field. We map the problem onto the dynamics of two interacting anisotropic spins, and calculate the precession frequencies exactly both below and above Bose condensation. We demonstrate a relation between Rabi oscillations and internal Josephson oscillations, and find that an analogue of the internal Josephson effect exists in a non-condensed system.en_US
dc.description.abstract(cont.) We also derive the transport equation for a dilute Fermi system and find that the dependence of the precession frequencies on interparticle interactions is very weak for fermions.en_US
dc.description.statementofresponsibilityby Mehmet Özgür Oktel.en_US
dc.format.extent96 leavesen_US
dc.format.extent5672498 bytes
dc.format.extent5672259 bytes
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582
dc.subjectPhysics.en_US
dc.titleOptical excitations in cold gasesen_US
dc.typeThesisen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Physics
dc.identifier.oclc50407202en_US


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