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1
Christandl, Katharina. "Advancing neutral atom quantum computing studies of one-dimensional and two-dimensional optical lattices on a chip /." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1123263229.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xxiii, 261 p.; also includes graphics. Includes bibliographical references (p. 256-261). Available online via OhioLINK's ETD Center
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李德豪 and Tak-ho Alex Li. "Stripe quantum well waveguides using implantation induced optical confinement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31237381.
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Li, Tak-ho Alex. "Stripe quantum well waveguides using implantation induced optical confinement /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19145421.
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Wang, Chia-Jean. "Sub-diffraction quantum dot nanophotonic waveguides /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/5879.
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Na, Kyungsun. "Quantum transport in an electron waveguide /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Platt, Andrew. "Fano resonance in two-dimensional quantum wires with an offset attractive impurity." Virtual Press, 2004. http://liblink.bsu.edu/uhtbin/catkey/1294896.
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Our previous computational studies of two-dimensional quantum waveguide structures formed at the interface of the A1GaAs/GaAs heterostructure have focused on systems with centered attractive potential wells. From those studies we direct our attention to the quantum waveguide structures with an attractive potential well placed asymmetrically in the transverse direction. In particular, we are interested in the conductance spectrum for higher energy regimes where Fano resonances are the dominant resonance form. Of interest is the change and progression of Fano resonance peaks as a function of both the potentials' depth and offset, especially as it relates to the Breit-Wigner resonance forms observed in lower energy regimes. To accomplish this, the hard-wall models and Fortran code in our previous work have been expanded to include the asymmetrical positioning through solving the single-electron Schrodinger and associated equations used in the tight-binding Hamiltonian and recursive Green's functions. The observed Fano resonance structures are fitted to their characteristic equations through the use of zero-pole pairs.Department of Physics and Astronomy
7
Young, Christina Rachel. "FT-IRr and quantum cascade laser spectroscopy towards a hand-held trace gas sensor for benzene, toluene, and xylenes (BTX)." Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31702.
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Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010.Committee Chair: Boris Mizaikoff; Committee Member: Facundo Fernandez; Committee Member: Jiri Janata; Committee Member: Mark Disko; Committee Member: Oliver Brand; Committee Member: Thomas Orlando. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Modoran, Andrei V. "Classical and quantum dynamics of atomic systems in the proximity of dielectric waveguides." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1164654528.
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Sundaram, Ganesh. "Wave-packet dynamics in slowly perturbed crystals : gradient corrections and Berry-phase effects /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Wu, Xiucheng. "A wavelength monitor based on electroabsorption in quantum well waveguide photodiodes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0032/NQ66247.pdf.
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Hall, John Spencer. "A Study of the Performance of D-Wave Quantum Computers Using Spanning Trees." Thesis, Mississippi State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10792350.
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The performances of two D-Wave 2 machines (476 and 496 qubits) and of a 1097-qubit D-Wave 2X were investigated. Each chip has a Chimera interaction graph G. Problem input consists of values for the fields hj and for the two-qubit interactions Ji,j of an Ising spin-glass problem formulated on G. Output is returned in terms of a spin configuration {sj}, with sj = +1 or –1. We generated random spanning trees (RSTs) uniformly distributed over all spanning trees of G. On the 476-qubit D-Wave 2, RSTs were generated on the full chip with Ji,j = –1 and hj = 0 and solved one thousand times. The distribution of solution energies and the average magnetization of each qubit were determined. On both the 476- and 1097- qubit machines, four identical spanning trees were generated on each quadrant of the chip. The statistical independence of these regions was investigated.
12
Oliveira, Eduardo M. A. "Thermal and quantum analysis of a stored state in a photonic crystal CROW structure." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-112007-105238/.
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Thesis (M.S.) -- Worcester Polytechnic Institute.Keywords: CROW; PBG; PhC; coupled resonator optical waveguide; metamaterials; photonic crystal; Bloch wave; photonic band gap;dynamic waveguide; Brillouin zone; thermal spreading. Includes bibliographical references (p. 84-87).
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Young, Christina Rachel. "FT-IR and quantum cascade laser spectroscopy towards a hand-held trace gas sensor for benzene, toluene, and xylenes (BTX)." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31702.
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The work described herein focuses on FT-IR and quantum cascade laser (QCL) based studies towards the development of compact and portable trace gas sensor for benzene, toluene, and xylenes (BTX). FT-IR broadband radiation was used to probe the mid-infrared fingerprint region for quantitatively detecting trace gas levels of BTX. Using direct absorption through a hollow waveguide, parts-per-million (ppm) detection limits for BTX with a response time of 39 seconds was demonstrated. Univariate calibration provided limits of detection (3σ) for benzene, toluene, and meta-xylene at 5, 17, and 11 ppm, respectively. Multivariate calibration using partial least squares regression algorithms were used to simulate real-world conditions with multiple analytes present within a complex sample. A calibration model was built with 110 training set standards enabled by using a customized gas mixing system. Furthermore, a preconcentration/thermal desorption (TD) step was added to the FT-IR HWG trace gas sensor enabling parts-per-billion detection of BTX. A univariate calibration was established in the laboratory with certified gas standards over a dynamic range of 1000 - 100 ppb for benzene, toluene, and the xylenes. The sensor was then taken to an industrial site during a field measurement campaign for the quantitative determination of BTX in field air samples. The laboratory calibration was used to predict unknown concentrations which were in close agreement with industrial hygiene standard techniques, and industrial prototype analyzers, that were simultaneously operated in the field environment.
In addition to FT-IR, quantum cascade laser spectroscopy was also investigated due to enhanced spectral density and efforts to precisely overlap emission with analyte absorption. Particular efforts were dedicated on a novel principle for consistent and deliberate QCL emission wavelength selection by varying the QCL cavity length. These studies experimentally confirmed that using this straight-forward post-processing technique, emission wavelength tuning across a range of one hundred wavenumbers range may be achieved. This tuning range was experimentally demonstrated for a QCL emitting across an entire absorption feature of carbon dioxide by tailoring the length of the cavity. Additionally, using an external cavity (EC) - QCL combined with a HWG gas sensor module for the first time enabled the quantitative and simultaneous determination of ethyl chloride, trichloromethane, and dichloromethane within exponential dilution experiments at ppb limits of detection. Multianalyte detection was demonstrated utilizing partial least squares regression for quantitative discrimination of individual constituents within a mixture, yet applying a single broadly tunable QCL light source.
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Tafur, Sergio. "Computational study of the near field spontaneous creation of photonic states coupled to few level systems." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5053.
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Models of the spontaneous emission and absorption of photons coupled to the electronic states of quantum dots, molecules, N-V (single nitrogen vacancy) centers in diamond, that can be modeled as artificial few level atoms, are important to the development of quantum computers and quantum networks. A quantum source modeled after an effective few level system is strongly dependent on the type and coupling strength the allowed transitions. These selection rules are subject to the Wigner-Eckert theorem which specifies the possible transitions during the spontaneous creation of a photonic state and its subsequent emission. The model presented in this dissertation describes the spatio-temporal evolution of photonic states by means of a Dirac-like equation for the photonic wave function within the region of interaction of a quantum source. As part of this aim, we describe the possibility to shift from traditional electrodynamics and quantum electrodynamics, in terms of electric and magnetic fields, to one in terms of a photonic wave function and its operators. The mapping between these will also be presented herein. It is further shown that the results of this model can be experimentally verified. The suggested method of verification relies on the direct comparison of the calculated density matrix or Wigner function, associated with the quantum state of a photon, to ones that are experimentally reconstructed through optical homodyne tomography techniques. In this non-perturbative model we describe the spontaneous creation of photonic state in a non-Markovian limit which does not implement the Weisskopf-Wigner approximation. We further show that this limit is important for the description of how a single photonic mode is created from the possibly infinite set of photonic frequencies vsubscript k] that can be excited in a dielectric-cavity from the vacuum state.; We use discretized central-difference approximations to the space and time partial derivatives, similar to finite-difference time domain models, to compute these results. The results presented herein show that near field effects need considered when describing adjacent quantum sources that are separated by distances that are small with respect to the wavelength of their spontaneously created photonic states. Additionally, within the future scope of this model, we seek results in the Purcell and Rabi regimes to describe enhanced spontaneous emission events from these few-level systems, as embedded in dielectric cavities. A final goal of this dissertation is to create novel computational and theoretical models that describe single and multiple photon states via single photon creation and annihilation operators.ID: 030423393; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 220-233).
Ph.D.
Doctorate
Physics
Sciences
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Al-Latifi, Yasir. "Optimizing numerical modelling of quantum computing hardware." Thesis, Umeå universitet, Institutionen för fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-182659.
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Quantum computers are being developed to solve certain problems faster than classical computers. Instead of using classical bits, they use quantum bits (qubits) that utilize quantum effects. At Chalmers University of Technology, researchers have already built a quantum chip consisting of two superconducting transmon qubits and are trying to build systems with more qubits. To assist in that process, they make numerical simulations of the quantum systems. However, these simulations face an intrinsic computational limitation: the Hilbert space of the system grows exponentially with the number of qubits. In order to mitigate the problem: the simulations should be made as efficient as possible, by applying certain approximations, while still obtaining accurate results. The aim of this project is to compare several of these approximations, to see how accurate they are and how fast they run on a classical computer. This is done by modelling the qubits as quantum anharmonic oscillators and testing several cases: varying the energy levels of the qubits, increasing the number of qubits, and testing the rotating-wave approximation (RWA). These cases were tested by implementing two-qubit gates on the system. The simulations were all made using the Python library QuTiP. The results show that one should simulate using at least one energy level higher than the maximum energy level required for the gate to function. For larger systems, the RWA will make a big difference in simulation times, while still giving relatively accurate results. When using the RWA, the number of levels used does not seem to affect the results significantly and one could therefore use the lowest possible energy levels that can simulate the system.
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Thomas, Mikkel Andrey. "Integrated optical interferometric sensors on silicon and silicon cmos." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26674.
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The main objective of this research is to fabricate and characterize an optically integrated interferometric sensor on standard silicon and silicon CMOS circuitry. An optical sensor system of this nature would provide the high sensitivity and immunity to electromagnetic interference found in interferometric based sensors in a lightweight, compact package capable of being deployed in a multitude of situations inappropriate for standard sensor configurations. There are several challenges involved in implementing this system. These include the development of a suitable optical emitter for the sensor system, the interface between the various optically embedded components, and the compatibility of the Si CMOS with heterogeneous integration techniques. The research reported outlines a process for integrating an integrated sensor on Si CMOS circuitry using CMOS compatible materials, integration techniques, and emitter components.
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Bain, Fiona Mair. "Yb:tungstate waveguide lasers." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1698.
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Lasers find a wide range of applications in many areas including photo-biology, photo-chemistry, materials processing, imaging and telecommunications. However, the practical use of such sources is often limited by the bulky nature of existing systems. By fabricating channel waveguides in solid-state laser-gain materials more compact laser systems can be designed and fabricated, providing user-friendly sources. Other advantages inherent in the use of waveguide gain media include the maintenance of high intensities over extended interaction lengths, reducing laser thresholds. This thesis presents the development of Yb:tungstate lasers operating around 1μm in waveguide geometries. An Yb:KY(WO₄)₂ planar waveguide laser grown by liquid phase epitaxy is demonstrated with output powers up to 190 mW and 76 % slope efficiency. This is similar to the performance from bulk lasers but in a very compact design. Excellent thresholds of only 40 mW absorbed pump power are realised. The propagation loss is found to be less than 0.1 dBcm⁻¹ and Q-switched operation is also demonstrated. Channel waveguides are fabricated in Yb:KGd(WO₄)₂ and Yb:KY(WO₄)₂ using ultrafast laser inscription. Several of these waveguides lase in compact monolithic cavities. A maximum output power of 18.6 mW is observed, with a propagation loss of ~2 dBcm⁻¹. By using a variety of writing conditions the optimum writing pulse energy is identified. Micro-spectroscopy experiments are performed to enable a fuller understanding of the induced crystal modification. Observations include frequency shifts of Raman lines which are attributed to densification of WO₂W bonds in the crystal. Yb:tungstate lasers can generate ultrashort pulses and some preliminary work is done to investigate the use of quantum dot devices as saturable absorbers. These are shown to have reduced saturation fluence compared to quantum well devices, making them particularly suitable for future integration with Yb:tungstate waveguides for the creation of ultrafast, compact and high repetition rate lasers.
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Böhm, Julian. "Phénomènes de transport originaux dans des expériences micro-ondes via la mise en forme spatiale et spectrale." Thesis, Université Côte d'Azur (ComUE), 2016. http://www.theses.fr/2016AZUR4048/document.
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Le transport des ondes joue un rôle majeur dans les systèmes de communication comme le Wifi ou les fibres optiques. Les principaux problèmes rencontrés dans ces systèmes concernent la protection contre les intrusions, la consommation d’énergie et le filtrage modal. Nous proposons différentes expériences micro-ondes mettant toutes en œuvre une mise en forme des ondes, pour traiter ces problèmes. Dans une cavité micro-ondes, des états de diffusion particuliers sont générés en s’appuyant uniquement sur des mesures de transmission et sur le formalisme du temps de retard de Wigner-Smith. Ces états sont capables d’éviter une région déterminée de la cavité, de se concentrer sur un point particulier, ou de suivre une trajectoire d’une particule classique. Le filtrage de mode est mis en œuvre dans un guide d’ondes aux frontières ondulées et en présence de pertes dépendant de la position. Le profil du guide est choisi de façon à ce que les deux modes de Bloch qui se propagent encerclent un point exceptionnel. Cette trajectoire s’accompagne d’une transition non-adiabatique entre les deux modes et d'un filtrage asymétrique de ces modes. La thèse présente également des travaux liés à la problématique des algorithmes de « recherche quantique », notamment l’algorithme de Grover. Cette recherche est mise en œuvre dans un réseau en nid d’abeilles de résonateurs micro-ondes couplés, bien décrits par un modèle de liaisons fortes (le système constitue un analogue micro-ondes du graphène). Une expérience de preuve de principe propose la recherche de deux résonateurs distincts reliés au réseau. La loi d’échelle attendue pour cet algorithme est expérimentalement obtenue dans une chaîne linéaireTransport of waves plays an important role in modern communication systems like Wi-Fi or optical fibres. Typical problems in such systems concern security against possible intruders, energy consumption, time efficiency and the possibility of mode filtering. Microwave experiments are suited to study this kind of problems, because they offer a good control of the experimental parameters. Thus we can implement the method of wave shaping to investigate atypical transport phenomena, which address the mentioned problems. Wave front shaping solely based on the transmission together with the Wigner-Smith time delay formalism allows me to establish special scattering states in situ. These scattering states avoid a pre-selected region, focus on a specific spot or follow trajectories of classical particles, so called particle-like scattering states. Mode filtering is induced inside a waveguide with wavy boundaries and position dependent loss. The boundary profiles are chosen in such a way that the two propagating modes describe an encircling of an exceptional point in the Bloch picture. The asymmetric mode filtering is found due to the appearing non-adiabatic transitions. Another part of my work deals with Grover’s quantum search. I put such a search into practice in a two-dimensional graphene-lattice using coupled resonators, which form a tight-binding analogue. In this proof of principle experiment we search for different resonators attached to the graphene-lattice. Furthermore, the scaling behaviour of the quantum search is quantified for a linear chain of resonators
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Snyder, Michael Garrett. "Quantum computation with ballistic electron waveguides." Thesis, 2006. http://hdl.handle.net/2152/2647.
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Srinivasan, Prashant. "INVESTIGATION OF QUANTUM FLUCTUATIONS IN A NONLINEAR INTERFEROMETER WITH HARMONIC GENERATION AND COHERENT INTERACTION OF LIGHT AND CS ATOMS." 2013. http://hdl.handle.net/1805/3465.
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Indiana University-Purdue University Indianapolis (IUPUI)In the first part of this thesis, we investigate the propagation of quantum fluctuations in a nonlinear interferometer comprising under conditions of harmonic generation by computer simulations. This investigation assumes idealized conditions such as lossless and uniform nonlinear media, an ideal cavity and ideal photodetectors. After linearizing wave equations for harmonic generation with a coherent state input, we obtain equations for one dimensional spatial propagation of the mean field and quantum fluctuations for initial conditions set by arbitrary interferometer phase. We discover that fluctuations are de-squeezed in the X and Y quadratures as the interferometer phase is tuned. However, we discover that there is are quadratures P-Q obtained by rotating the X-Y quadratures for which squeezing is improved by factors of 10^9. We present a practical idea to implement rotation of X quadrature fluctuations to the Q quadrature by using an ideal empty optical cavity. Signal-to-Noise ratio of the nonlinear interferometer was calculated and compared with that of a linear interferometer with coherent state input. We calculated a maximum performance improvement of a factor of 60 for a normalized propagation length ζ0 = 3 under ideal conditions. In the second part of this thesis, we investigate experimentalarrangements to transfer atomic coherence from light to cesium atoms. We discuss the experimental arrangement to generate coherence under conditions of electromagnetically induced transparency (EIT). We measure a continuous wave EIT width of 7.18 MHz and present results for pulsed arrangements.
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Ghohroodi, Ghamsari Behnood. "Guided-Wave Superconducting Quantum Optoelectronic Devices." Thesis, 2010. http://hdl.handle.net/10012/5252.
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This thesis investigates a novel optoelectronic platform based on
the integration of superconductive structures, such as thin films
and micro-constrictions, with optical waveguides for ultra-fast and
ultra-sensitive devices with applications including high-speed
optical communications, quantum optical information processing, and
terahertz (THz) devices and systems.
The kinetic-inductive photoresponse of superconducting thin films
will be studied as the basic optoelectronic process underlying the
operation of these novel devices. Analytical formulation for the
non-bolometric response is presented, and experimental
photodetection in YBCO meander-line structures will be demonstrated.
A set of superconducting coplanar waveguides (CPW) are designed and
characterized, which support the operation of the devices at
microwave frequencies. Microwave-photonic devices comprising a
microwave transmission line and a light-sensitive element, such as a
meander-line structure, are designed and measured for implementation
of optically tunable microwave components.
In order to support low-loss and low-dispersion propagation of
millimeter-wave and THz signals in ultra-fast and wideband
kinetic-inductive devices, surface-wave transmission lines are
proposed, incorporating long-wavelength Surface Plasmon Polariton
(SPP) modes in planar metal-dielectric waveguides.
The theory of superconducting optical waveguides, including
analytical formulation and numerical methods, is developed in
detail. The implementation of superconducting optical waveguides is
discussed thoroughly, employing conventional dielectric-waveguide
techniques as well as optical SPP modes.
Superconductive traveling-wave photodetectors (STWPDs) are
introduced as a viable means for ultra-fast and ultra-sensitive
photodetection and photomixing. A modified transmission line
formalism is developed to model STWPDs, where light is guided
through an optical waveguide and photodetection is distributed along
a transmission line.
As an appendix, a systematic approach is developed for the analysis
of carrier transport through superconducting heterostructures and
micro-constrictions within the Bogoliubov-de Gennes (BdG) framework.
The method is applied to study the role of Andreev reflection and
Josephson-like phenomena in the current-voltage characteristics of
inhomogeneous superconducting structures. I-V characteristics are
experimentally demonstrated in YBCO micro-constrictions with
potential applications in millimeter-wave and THz devices.
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Ting, Chu Ong. "Suppression of radiation damping in electromagnetic waveguide, signature of quantum decoherence in the field bath." Thesis, 2003. http://wwwlib.umi.com/cr/utexas/fullcit?p3116206.
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Weisshaar, Andreas. "Generalized modal analysis of electromagnetic- and quantum-waveguide structures and discontinuities." Thesis, 1991. http://hdl.handle.net/1957/37423.
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Generalized modal analysis techniques for the characterization and modeling of
dissipationless planar waveguide structures and discontinuities encountered in microwave
and optical integrated circuits, as well as of quantum waveguide structures and devices,
are presented.
The frequency-dependent transmission properties of the curved microstrip bend
are derived by utilizing a second-order perturbation analysis of the equivalent modified
curved waveguide model and a mode-matching method which includes the higher order
modes. An extension of the mode-matching method for characterization of microstrip
right-angle bends and T junctions having a rectangular notch is formulated.
The modal solutions for an arbitrary graded-index dielectric slab waveguide are
derived by applying the generalized telegraphist's equations to the equivalent inhomogeneous
parallel-plate waveguide model with electric or magnetic walls. These modal
solutions are employed in a mode-matching procedure to calculate the transmission
properties of a step discontinuity in typical diffused optical dielectric slab waveguides.
Power loss calculations for an abrupt offset in a diffused optical waveguide show a
smooth increase in radiation loss whereas a sharp transition from almost zero to nearly
total radiation loss is found for an abrupt change in diffusion depth.
In the analysis of quantum waveguide structures, the modal expansions of the
wave function together with a mode-matching technique are utilized. The computed
generalized scattering matrices (GSMs) of junctions and uniform waveguide sections
are combined via an extended GSM technique to obtain the scattering parameters of
composite quantum waveguide structures. Results for cascaded right-angle bends and
periodic multi-waveguide structures in a split-gate configuration are presented assuming
hard wall confinement. For the multisection structures, strong resonant behavior similar
to that in resonant tunneling diodes is found. Calculated current-voltage characteristics
for a double constriction in GaAs are shown, exhibiting a region of negative differential
resistance for temperatures up to approximately 60K with a maximum peak-to-valley
ratio of over 80:1. Finally, a uniform narrow constriction with an assumed parabolic -
like lateral potential confinement is analyzed by utilizing the modal expansion
techniques developed for dielectric waveguides.Graduation date: 1991
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"Optical analogue of interacting quantum and mechanical systems: spin and plane pendulum." 2013. http://library.cuhk.edu.hk/record=b5884310.
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Au-Yeung, Kin Chung = 以光學模擬量子自旋和機械鐘擺的相互作用 / 歐陽健聰.Thesis (M.Phil.)--Chinese University of Hong Kong, 2013.
Includes bibliographical references (leaves 80-81).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts also in Chinese.
Au-Yeung, Kin Chung = Yi guang xue mo ni liang zi zi xuan he ji xie zhong bai de xiang hu zuo yong / Ouyang Jiancong.
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"Photon-atom interactions in a one-dimensional waveguide." 2009. http://library.cuhk.edu.hk/record=b5896583.
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Tsoi, Tze Shun = 光子和原子在一維波導中的相互作用 / 蔡子淳.Thesis (M.Phil.)--Chinese University of Hong Kong, 2009.
Includes bibliographical references (leaves 94-97).
Abstract also in Chinese.
Tsoi, Tze Shun = Guang zi he yuan zi zai yi wei bo dao zhong de xiang hu zuo yong / Cai Zichun.
Chapter 1 --- Introduction --- p.1
Chapter 2 --- Basic description of QED in a one-dimensional waveguide --- p.4
Chapter 2.1 --- EM fields in a waveguide: from classical to quantum --- p.4
Chapter 2.1.1 --- Classical EM fields in a conducting waveguide --- p.5
Chapter 2.1.2 --- Quantization of the electromagnetic fields --- p.8
Chapter 2.2 --- "Atom, dipole interactions and interaction models" --- p.11
Chapter 2.2.1 --- Atom and dipole interactions --- p.12
Chapter 2.2.2 --- Two-level atom --- p.12
Chapter 2.2.3 --- A-atom --- p.14
Chapter 2.3 --- Comparison: waveguide vs free space --- p.15
Chapter 2.3.1 --- Electric field intensity of a photon packet --- p.15
Chapter 2.3.2 --- Spontaneous decay rate --- p.16
Chapter 3 --- Single-excitation solution for two-level atoms --- p.20
Chapter 3.1 --- Case of a single atom --- p.20
Chapter 3.2 --- Case of a chain of N identical atoms --- p.26
Chapter 3.2.1 --- The Hamiltonian and eigenvectors --- p.27
Chapter 3.2.2 --- Transmission spectrum of a single photon --- p.31
Chapter 3.2.3 --- Dynamics of spontaneous emission --- p.34
Chapter 3.3 --- Dissipative loss to non-waveguide modes --- p.39
Chapter 3.4 --- Interactions with non-identical atoms --- p.41
Chapter 3.4.1 --- Vacuum Rabi oscillations using atomic mirrors --- p.42
Chapter 3.4.2 --- Atoms with non-identical resonant energies --- p.46
Chapter 4 --- Two-photon transport with a two-level atom --- p.50
Chapter 4.1 --- The energy eigenstate solution --- p.51
Chapter 4.1.1 --- Single-photon case --- p.51
Chapter 4.1.2 --- Two-photon case --- p.53
Chapter 4.2 --- Laplace transformation method --- p.57
Chapter 4.2.1 --- Single-photon case --- p.58
Chapter 4.2.2 --- Two-photon case --- p.61
Chapter 4.2.3 --- Lorentzian-packet states --- p.64
Chapter 4.2.4 --- Photon-photon correlations --- p.65
Chapter 5 --- Interactions with A-atoms --- p.70
Chapter 5.1 --- Hamiltonian and eigenvectors --- p.71
Chapter 5.1.1 --- N = 1 case --- p.71
Chapter 5.1.2 --- N > 1 case --- p.75
Chapter 5.2 --- Final state properties --- p.80
Chapter 5.2.1 --- Polarization dependent transmission and reflection --- p.80
Chapter 5.2.2 --- Collective atomic states --- p.82
Chapter 5.2.3 --- Scattering with a photon wave packet --- p.83
Chapter 5.3 --- Decoherence: effects of the coupling with the non-waveguide modes --- p.85
Chapter 5.4 --- Application: an “NM´ح polarizer made of a few atoms --- p.86
Chapter 6 --- Conclusion --- p.91
Bibliography --- p.94
Chapter A --- Derivation of the one-dimensional spontaneous rate r1d --- p.98
Chapter B --- Description of a photon packet --- p.101
Chapter C --- Derivation of the two-photon packet solution --- p.105
Chapter D --- “Completeness´ح of the two-photon Lorentzian-packet states --- p.108
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Lee, Hoshik 1975. "Quantum chaos and electron transport properties in a quantum waveguide." Thesis, 2008. http://hdl.handle.net/2152/3914.
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We numerically investigate electron transport properties in an electron waveguide which can be constructed in 2DEG of the heterostructure of GaAs and AlGaAs. We apply R-matrix theory to solve a Schrödinger equation and construct a S-matrix, and we then calculate conductance of an electron waveguide. We study single impurity scattering in a waveguide. A [delta]-function model as a single impurity is very attractive, but it has been known that [delta]-function potential does not give a convergent result in two or higher space dimensions. However, we find that it can be used as a single impurity in a waveguide with the truncation of the number of modes. We also compute conductance for a finite size impurity by using R-matrix theory. We propose an appropriate criteria for determining the cut-off mode for a [delta]-function impurity that reproduces the conductance of a waveguide when a finite impurity presents. We find quantum scattering echoes in a ripple waveguide. A ripple waveguide (or cavity) is widely used for quantum chaos studies because it is easy to control a particle's dynamics. Moreover we can obtain an exact expression of Hamiltonian matrix with for the waveguide using a simple coordinate transformation. Having an exact Hamiltonian matrix reduces computation time significantly. It saves a lot of computational needs. We identify three families of resonance which correspond to three different classical phase space structures. Quasi bound states of one of those resonances reside on a hetero-clinic tangle formed by unstable manifolds and stable manifolds in the phase space of a corresponding classical system. Resonances due to these states appear in the conductance in a nearly periodic manner as a function of energy. Period from energy frequency gives a good agreement with a prediction of the classical theory. We also demonstrate wavepacket dynamics in a ripple waveguide. We find quantum echoes in the transmitted probability of a wavepacket. The period of echoes also agrees with the classical predictions. We also compute the electron transmission probability through a multi-ripple electron waveguide. We find an effect analogous to the Dicke effect in the multi-ripple electron waveguide. We show that one of the S-matrix poles, that of the super-radiant resonance state, withdraws further from the real axis as each ripple is added. The lifetime of the super-radiant state, for N quantum dots, decreases as [1/N] . This behavior of the lifetime of the super-radiant state is a signature of the Dicke effect.text
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Bowden, Bradley. "Design theory, materials selection, and fabrication of hollow core waveguides for infrared to THz radiation." 2007. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.15790.
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Thompson, Clinton Edward. "Quantum physics inspired optical effects in evanescently coupled waveguides." Thesis, 2014. http://hdl.handle.net/1805/6161.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)The tight-binding model that has been used for many years in condensed matter physics, due to its analytic and numerical tractability, has recently been used to describe light propagating through an array of evanescently coupled waveguides. This dissertation presents analytic and numerical simulation results of light propagating in a waveguide array. The first result presented is that photonic transport can be achieved in an array where the propagation constant is linearly increasing across the array. For an input at the center waveguide, the breathing modes of the system are observed, while for a phase displaced, asymmetric input, phase-controlled photonic transport is predicted. For an array with a waveguide-dependent, parity-symmetric coupling constant, the wave packet dynamics are predicted to be tunable. In addition to modifying the propagation constant, the coupling between waveguides can also be modified, and the quantum correlations are sensitive to the form of the tunneling function. In addition to modifying the waveguide array parameters in a structured manner, they can be randomized as to mimic the insertion of impurities during the fabrication process. When the refractive indices are randomized and real, the amount of light that localizes to the initial waveguide is found to be dependent on the initial waveguide when the waveguide coupling is non-uniform. In addition, when the variance of the refractive indices is small, light localizes in the initial waveguide as well as the parity-symmetric waveguide. In addition to real valued disorder, complex valued disorder can be introduced into the array through the imaginary component of the refractive index. It is shown that the two-particle correlation function is qualitatively similar to the case when the waveguide coupling is real and random, as both cases preserve the symmetry of the eigenvalues. Lastly, different input fields have been used to investigate the quantum statistical aspects of Anderson localization. It is found that the fluctuations in the output intensity are enhanced and the entropy of the system is reduced when disorder is present in the waveguides.
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Scott, Derek Douglas. "An investigation of parity and time-reversal symmetry breaking in tight-binding lattices." Thesis, 2014. http://hdl.handle.net/1805/6106.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)More than a decade ago, it was shown that non-Hermitian Hamiltonians with combined parity (P) and time-reversal (T ) symmetry exhibit real eigenvalues over a range of parameters. Since then, the field of PT symmetry has seen rapid progress on both the theoretical and experimental fronts. These effective Hamiltonians are excellent candidates for describing open quantum systems with balanced gain and loss. Nature seems to be replete with examples of PT -symmetric systems; in fact, recent experimental investigations have observed the effects of PT symmetry breaking in systems as diverse as coupled mechanical pendula, coupled optical waveguides, and coupled electrical circuits. Recently, PT -symmetric Hamiltonians for tight-binding lattice models have been extensively investigated. Lattice models, in general, have been widely used in physics due to their analytical and numerical tractability. Perhaps one of the best systems for experimentally observing the effects of PT symmetry breaking in a one-dimensional lattice with tunable hopping is an array of evanescently-coupled optical waveguides. The tunneling between adjacent waveguides is tuned by adjusting the width of the barrier between them, and the imaginary part of the local refractive index provides the loss or gain in the respective waveguide. Calculating the time evolution of a wave packet on a lattice is relatively straightforward in the tight-binding model, allowing us to make predictions about the behavior of light propagating down an array of PT -symmetric waveguides. In this thesis, I investigate the the strength of the PT -symmetric phase (the region over which the eigenvalues are purely real) in lattices with a variety of PT - symmetric potentials. In Chapter 1, I begin with a brief review of the postulates of quantum mechanics, followed by an outline of the fundamental principles of PT - symmetric systems. Chapter 2 focuses on one-dimensional uniform lattices with a pair of PT -symmetric impurities in the case of open boundary conditions. I find that the PT phase is algebraically fragile except in the case of closest impurities, where the PT phase remains nonzero. In Chapter 3, I examine the case of periodic boundary conditions in uniform lattices, finding that the PT phase is not only nonzero, but also independent of the impurity spacing on the lattice. In addition, I explore the time evolution of a single-particle wave packet initially localized at a site. I find that in the case of periodic boundary conditions, the wave packet undergoes a preferential clockwise or counterclockwise motion around the ring. This behavior is quantified by a discrete momentum operator which assumes a maximum value at the PT -symmetry- breaking threshold. In Chapter 4, I investigate nonuniform lattices where the parity-symmetric hop- ping between neighboring sites can be tuned. I find that the PT phase remains strong in the case of closest impurities and fragile elsewhere. Chapter 5 explores the effects of the competition between localized and extended PT potentials on a lattice. I show that when the short-range impurities are maximally separated on the lattice, the PT phase is strengthened by adding short-range loss in the broad-loss region. Consequently, I predict that a broken PT symmetry can be restored by increasing the strength of the short-range impurities. Lastly, Chapter 6 summarizes my salient results and discusses areas which can be further developed in future research.