1 
Broadband teleportation and entanglement in cascaded open quantum systemsNoh, Changsuk January 2009 (has links)
Quantum optics provides powerful means to probe quantum mechanics. In this thesis, we study various aspects of quantum phenomena arising in quantum optical systems. Part I studies broadband quantum teleportation. After presenting three different methods of analyzing the standard teleportation protocol, we study the interplay between various bandwidths in determining the fidelity of a broadband quantum field teleportation. Explicit formulae for the degrees of first and secondorder coherence for the teleportation of resonance fluorescence are derived for this purpose. Part II studies entanglement arising in cascaded open quantum (optical) systems. First, a detailed laser model is produced within quantum trajectory theory to study the total decoherence rate of a laserdriven qubit. Second, using this model, we address the issue of laser quantum state, viewed in connection with separability of the laserdrivenqubit system. Third, a measure of entanglement within quantum trajectory theory called ‘Contextual Entanglement’ is calculated for a few simple systems and compared with the ‘Entanglement of Formation’. Lastly, we introduce a method to quantify entanglement (based on the contextual entanglement) between a source and the field it emits, which we call the ‘Entanglement Spectrum’. It is applied to study the entanglement between a laserdriven qubit and the field the qubit scatters.

2 
The micromaser theory and comparison to experimentJohnson, David Brian, Schieve, W. C., January 2003 (has links) (PDF)
Thesis (Ph. D.)University of Texas at Austin, 2003. / Supervisor: William C. Schieve. Vita. Includes bibliographical references. Available also from UMI Company.

3 
The micromaser theory and comparison to experimentJohnson, David Brian 28 August 2008 (has links)
Not available / text

4 
Broadband teleportation and entanglement in cascaded open quantum systemsNoh, Changsuk January 2009 (has links)
Quantum optics provides powerful means to probe quantum mechanics. In this thesis, we study various aspects of quantum phenomena arising in quantum optical systems. Part I studies broadband quantum teleportation. After presenting three different methods of analyzing the standard teleportation protocol, we study the interplay between various bandwidths in determining the fidelity of a broadband quantum field teleportation. Explicit formulae for the degrees of first and secondorder coherence for the teleportation of resonance fluorescence are derived for this purpose. Part II studies entanglement arising in cascaded open quantum (optical) systems. First, a detailed laser model is produced within quantum trajectory theory to study the total decoherence rate of a laserdriven qubit. Second, using this model, we address the issue of laser quantum state, viewed in connection with separability of the laserdrivenqubit system. Third, a measure of entanglement within quantum trajectory theory called ‘Contextual Entanglement’ is calculated for a few simple systems and compared with the ‘Entanglement of Formation’. Lastly, we introduce a method to quantify entanglement (based on the contextual entanglement) between a source and the field it emits, which we call the ‘Entanglement Spectrum’. It is applied to study the entanglement between a laserdriven qubit and the field the qubit scatters.

5 
Broadband teleportation and entanglement in cascaded open quantum systemsNoh, Changsuk January 2009 (has links)
Quantum optics provides powerful means to probe quantum mechanics. In this thesis, we study various aspects of quantum phenomena arising in quantum optical systems. Part I studies broadband quantum teleportation. After presenting three different methods of analyzing the standard teleportation protocol, we study the interplay between various bandwidths in determining the fidelity of a broadband quantum field teleportation. Explicit formulae for the degrees of first and secondorder coherence for the teleportation of resonance fluorescence are derived for this purpose. Part II studies entanglement arising in cascaded open quantum (optical) systems. First, a detailed laser model is produced within quantum trajectory theory to study the total decoherence rate of a laserdriven qubit. Second, using this model, we address the issue of laser quantum state, viewed in connection with separability of the laserdrivenqubit system. Third, a measure of entanglement within quantum trajectory theory called ‘Contextual Entanglement’ is calculated for a few simple systems and compared with the ‘Entanglement of Formation’. Lastly, we introduce a method to quantify entanglement (based on the contextual entanglement) between a source and the field it emits, which we call the ‘Entanglement Spectrum’. It is applied to study the entanglement between a laserdriven qubit and the field the qubit scatters.

6 
Broadband teleportation and entanglement in cascaded open quantum systemsNoh, Changsuk January 2009 (has links)
Quantum optics provides powerful means to probe quantum mechanics. In this thesis, we study various aspects of quantum phenomena arising in quantum optical systems. Part I studies broadband quantum teleportation. After presenting three different methods of analyzing the standard teleportation protocol, we study the interplay between various bandwidths in determining the fidelity of a broadband quantum field teleportation. Explicit formulae for the degrees of first and secondorder coherence for the teleportation of resonance fluorescence are derived for this purpose. Part II studies entanglement arising in cascaded open quantum (optical) systems. First, a detailed laser model is produced within quantum trajectory theory to study the total decoherence rate of a laserdriven qubit. Second, using this model, we address the issue of laser quantum state, viewed in connection with separability of the laserdrivenqubit system. Third, a measure of entanglement within quantum trajectory theory called ‘Contextual Entanglement’ is calculated for a few simple systems and compared with the ‘Entanglement of Formation’. Lastly, we introduce a method to quantify entanglement (based on the contextual entanglement) between a source and the field it emits, which we call the ‘Entanglement Spectrum’. It is applied to study the entanglement between a laserdriven qubit and the field the qubit scatters.

7 
Theory of multiwave mixing in two and threelevel media.An, Sunghyuck. January 1988 (has links)
This dissertation presents theories of multiwave mixing in two and threelevel media. The first part of the dissertation treats the semiclassical theories in twolevel media. Chapter 2 gives the simple semiclassical theory of fourwave mixing when the two pump frequences differ by more than the reciprocal of the populationdifference lifetime. This difference washes out the pump spatial holes as well as one of the two reflection gratings. We compare the results to the degenerate treatment of Abrams and Lind and find significant differences in the reflection coefficient spectra. Chapter 3 presents the semiclassical theory of multiwave in a squeezed vacuum characterized by unequal inphase and inquadrature dipole decay times. For a highly squeezed vacuum, we find sharp resonances in both probe absorption and reflection coefficients, which provide sensitive ways to measure the amount of squeezing in the vacuum. The second part of the dissertation treats the quantum theories in two and threelevel media. Chapter 4 develops the fourthorder quantum theory of multiwave mixing to describe the effects of sidemode saturation in twolevel media. We derive explicit formulas for the fourthorder quantum coefficients and show that the fourthorder quantum theory reproduces the thirdorder semiclassical coefficient obtained by truncating a continued fraction. We apply the results to cavity problems and find significant differences in the sideband spectra given by the second and fourthorder treatments, particularly as the sidemode approaches the laser threshold. The final chapter presents a quantum theory of multiwave mixing in threelevel cascades with a twophoton pump. The explicit formulas for the resonance fluorescence spectrum and the quantum combinationtone source term are derived. The theory is applied to the generation of squeezed states of light. We find almost perfect squeezing for some strong pump intensities and good broadband squeezing for low pump intensities.

8 
Entanglement manipulations and applicationsBose, Sougato January 2000 (has links)
No description available.

9 
Stimulated parametric downconversion and quantum cloningLamas Linares, AntiÌa January 2002 (has links)
No description available.

10 
Quantum information processing in nanostructuresReina Estupin̄án, JohnHenry January 2002 (has links)
Since information has been regarded as a physical entity, the field of quantum information theory has blossomed. This brings novel applications, such as quantum computation. This field has attracted the attention of numerous researchers with backgrounds ranging from computer science, mathematics and engineering, to the physical sciences. Thus, we now have an interdisciplinary field where great efforts are being made in order to build devices that should allow for the processing of information at a quantum level, and also in the understanding of the complex structure of some physical processes at a more basic level. This thesis is devoted to the theoretical study of structures at the nanometerscale, "nanostructures," through physical processes that mainly involve the solidstate and quantum optics, in order to propose reliable schemes for the processing of quantum information. Initially, the main results of quantum information theory and quantum computation are briefly reviewed. Next, the stateoftheart of quantum dots technology is described. In so doing, the theoretical background and the practicalities required for this thesis are introduced. A discussion of the current quantum hardware used for quantum information processing is given. In particular, the solidstate proposals to date are emphasised. A detailed prescription is given, using an opticallydriven coupled quantum dot system, to reliably prepare and manipulate exciton maximally entangled Bell and GreenbergerHorneZeilinger (GHZ) states. Manipulation of the strength and duration of selective lightpulses needed for producing these highly entangled states provides us with crucial elements for the processing of solidstate based quantum information. The alloptical generation of states of the socalled Bell basis for a system of two quantum dots (QDs) is exploited for performing the quantum teleportation of the excitonic state of a dot in an array of three coupled QDs. Theoretical predictions suggest that several hundred single quantum bit rotations and controlledNOT gates could be performed before decoherence of the excitonic states takes place. In addition, the exciton coherent dynamics of a coupled QD system confined within a semiconductor single mode microcavity is reported. It is shown that this system enables the control of exciton entanglement by varying the coupling strength between the opticallydriven dot system and the microcavity. The exciton entanglement shows collapses and revivals for suitable amplitudes of the incident radiation field and dotcavity coupling strengths. The results given here could offer a new approach for the control of decoherence mechanisms arising from entangled "artificial molecules." In addition to these ultrafast coherent optical control proposals, an approach for reliable implementation of quantum logic gates and long decoherence times in a QD system based on nuclear magnetic resonance (NMR) is given, where the nuclear resonance is controlled by the ground state "magic number" transitions of fewelectron QDs in an external magnetic field. The dynamical evolution of quantum registers of arbitrary length in the presence of environmentallyinduced decoherence effects is studied in detail. The cases of quantum bits (qubits) coupling individually to different environments ("independent decoherence"), and qubits interacting collectively with the same reservoir ("collective decoherence") are analysed in order to find explicit decoherence functions for any number of qubits. The decay of the coherences of the register is shown to strongly depend on the input states: this sensitivity is a characteristic of both types of coupling (collective and independent) and not only of the collective coupling, as has been reported previously. A nontrivial behaviour  "recoherence"  is found in the decay of the offdiagonal elements of the reduced density matrix in the specific situation of independent decoherence. The results lead to the identification of decoherencefree states in the collective decoherence limit. These states belong to subspaces of the system's Hilbert space that do not become entangled with the environment, making them ideal elements for the engineering of "noiseless" quantum codes. The relations between decoherence of the quantum register and computational complexity based on the new dynamical results obtained for the register density matrix are also discussed. This thesis concludes by summarising and pointing out future directions, and in particular, by discussing some biological resonant energy transfer processes that may be useful for the processing of information at a quantum level.

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