Quantum cryptography offers a wonderful source for current and future research. The idea started in the early 1970s, and it continues to inspire work and development toward a popular goal, large-scale communication networks with strong security guarantees, based on quantum-mechanical properties. Quantum cryptography builds on the idea of exploiting physical properties to establish secure cryptographic operations. A particular quantum-based protocol has gathered interest in recent years for its use of mesoscopic coherent states. The AlphaEta protocol has been designed to exploit properties of coherent states of light to transmit data securely over an optical channel. AlphaEta aims to draw security from the uncertainty of any measurement of the transmitted coherent states due to intrinsic quantum noise. We propose a framework to combine this protocol with classical preprocessing, taking into account error-correction for the optical channel and establishing a strong provable security guarantee. Integrating a state-of-the-art solution for fast authenticated encryption is straightforward, but in this case the security analysis requires heuristic reasoning. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Thesis (Ph.D.)--Tufts University, 2004. / Adviser: Lawrence H. Ford. Submitted to the Dept. of Physics. Includes bibliographical references (leaves 154-155). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph.D) -- Australian National University, 2005.

Thesis (Ph.D.)--Physics, Georgia Institute of Technology, 2008. / Committee Chair: Eric A. Carlen; Committee Member: Jean Bellissard; Committee Member: Michael Loss; Committee Member: Predrag Cvitanovic.

Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2008. / Turgay Uzer, Committee Chair ; M. Raymond Flannery, Committee Member ; Chandra Raman, Committee Member ; Dragomir Davidovic, Committee Member ; Chongchun Zeng, Committee Member.

Esta dissertação descreve o movimento quântico de uma partícula numa barreira de potencial parabólica, condicionalmente este sistema é chamado de oscilador invertido. Determinamos estados quânticos semiclássicos como família de estados coerentes generalizados (ECG), sendo construídos através da adaptação do trabalho de Malkin e Man´ko, determinando-se um operador que seja integral do movimento, parametrizado por algumas constantes e reconhecido como operador de aniquilação, cujos auto-estados tem características dos estados comprimidos. Discutimos suas propriedades e observamos que é possível comparar ECG do oscilador invertido com ECG da partícula livre e oscilador harmônico obtidos na literatura. Também é feito um estudo do movimento puramente quântico (tunelamento) nas barreiras de potenciais do oscilador invertido e oscilador invertido truncado, por meio das soluções estacionárias exatas e aproximadas (JWKB), comparando os resultados obtidos em cada situação. / This dissertation describes the motion of a particle in a quantum potential barrier parabolic, this system is conditionally called inverted oscillator. Determined quantum states semi-classics like family generalized coherent states (GCS), being constructed by adapting work Malkin\'s and Man\'ko, determining an operator who is integral of the motion, parameterized for some constants and recognized as annihilation operator, whose eigenstates have characteristics of squeezed states. We discuss its properties and note that it is possible to compare the GCS of inverted oscillator with GCS the particle free and harmonic oscillator obtained in the literature. Also made a study of the movement purely quantum (tunneling) in the barriers potential inverted oscillator and truncated inverted oscillator by means of exact and approximate stationary solutions (JWKB), comparing the results obtained in each situation.

Fung, Shu Hong = 量子點內自旋弱量度的散粒噪聲相關理論 / 馮書航. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 80-85). / Abstracts in English and Chinese. / Fung, Shu Hong = Liang zi dian nei zi xuan ruo liang du de san li zao sheng xiang guan li lun / Feng Shuhang. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Review on measurement theory --- p.5 / Chapter 2.1 --- Weak measurement --- p.5 / Chapter 2.2 --- POVM formalism --- p.7 / Chapter 2.3 --- Noise spectroscopy --- p.8 / Chapter 3 --- Review on spin decoherence --- p.11 / Chapter 3.1 --- Longitudinal relaxation --- p.12 / Chapter 3.2 --- Transverse relaxation --- p.12 / Chapter 3.3 --- Inhomogeneous broadening --- p.13 / Chapter 3.4 --- Typical relaxation timescales --- p.14 / Chapter 4 --- Proof-of-principle setup --- p.15 / Chapter 4.1 --- Faraday rotation --- p.15 / Chapter 4.2 --- Polarization beam splitter --- p.17 / Chapter 4.3 --- Quantum state of the system --- p.19 / Chapter 5 --- Weak measurement on the spin --- p.22 / Chapter 5.1 --- POVM of measurement --- p.22 / Chapter 5.2 --- POVM of dephasing --- p.25 / Chapter 5.3 --- Interval distribution operator --- p.26 / Chapter 5.4 --- Interval distribution function without dephasing --- p.27 / Chapter 5.5 --- Second order correlation function without dephasing --- p.31 / Chapter 5.6 --- Interval distribution function with dephasing --- p.34 / Chapter 5.7 --- Second order correlation function with dephasing --- p.40 / Chapter 5.8 --- Effect of inhomogeneous broadening on g(2)(t) --- p.42 / Chapter 5.9 --- Third order correlation function --- p.43 / Chapter 5.10 --- Monte Carlo simulation --- p.44 / Chapter 5.11 --- Results and discussion --- p.46 / Chapter 5.11.1 --- Characteristics and implications of g(2)(t) --- p.46 / Chapter 5.11.2 --- "Characteristics and implications of g(3)(t1,t2)" --- p.47 / Chapter 6 --- Interval distribution function with random force models --- p.49 / Chapter 6.1 --- Impact collision model --- p.51 / Chapter 6.2 --- Modified diffusion model --- p.53 / Chapter 6.3 --- Difficulties in the calculation of g(2)(t) --- p.54 / Chapter 6.4 --- Kn as a measured quantity --- p.57 / Chapter 7 --- Conclusion --- p.59 / Chapter A --- Alternative derivation of k and higher order corrections --- p.62 / Chapter B --- Evaluation of integrals in the exponential --- p.70 / Chapter B.1 --- Integral of the form ∫ts + ∫vu --- p.70 / Chapter B.2 --- Integrals of the form ∫ts + ∫vu + ∫yz --- p.72 / Chapter C --- Evaluation of four-click events --- p.74 / Bibliography --- p.76

Thesis (Ph. D.)--University of Chicago, Dept. of Chemistry, August 2001. / Includes bibliographical references. Also available on the Internet.

PolarizaÃÃo quÃntica tem sido usada extensivamente no processo da informaÃÃo quÃntica e emaranhamento quÃntico à essencial para muitas Ãreas de pesquisas, incluindo computaÃÃo quÃntica. Nesse trabalho foi realizada uma investigaÃÃo do grau de polarizaÃÃo e do emaranhamento de uma famÃlia de estados quÃnticos conhecidos como estados coerentes de fÃtons adicionados. Tais estados podem ser Ãteis na distribuiÃÃo quÃntica de chaves e distribuiÃÃo de emaranhamento. Usamos os parÃmetro de Stokes e a funÃÃo Q para demonstrar que, de uma forma geral, a polarizaÃÃo de uma superposiÃÃo de dois estados coerentes bimodais de fÃtons adicionados aumenta significantemente com o nÃmero de fÃtons adicionados. TambÃm utilizamos a concorrÃncia para mostrar que a quantidade de emaranhamento nas superposiÃÃes citadas apresenta um comportamento que depende se o nÃmero de fÃtons adicionados em cada modo sÃo iguais ou diferentes. / Polarization has been used extensively in quantum information processing, and quantum entanglement is essential to many areas of research, including quantum computing. Here we investigate the degree of polarization and the entanglement of a family of quantum states known as photon-added entangled coherent states. Such states could serve as means of entanglement distribution and quantum key distribution. Using the quantum Stokes parameters and the Q function, we demonstrated that, in general, the polarization of a superposition of two two-mode photon-added coherent states increases significantly with the number of added photons. And using the concurrence, we showed that the amount of entanglement in this kind of superposition presents a behavior that is dependent on whether or not the number of added photons on each mode is the same.

Esta dissertação descreve o movimento quântico de uma partícula numa barreira de potencial parabólica, condicionalmente este sistema é chamado de oscilador invertido. Determinamos estados quânticos semiclássicos como família de estados coerentes generalizados (ECG), sendo construídos através da adaptação do trabalho de Malkin e Man´ko, determinando-se um operador que seja integral do movimento, parametrizado por algumas constantes e reconhecido como operador de aniquilação, cujos auto-estados tem características dos estados comprimidos. Discutimos suas propriedades e observamos que é possível comparar ECG do oscilador invertido com ECG da partícula livre e oscilador harmônico obtidos na literatura. Também é feito um estudo do movimento puramente quântico (tunelamento) nas barreiras de potenciais do oscilador invertido e oscilador invertido truncado, por meio das soluções estacionárias exatas e aproximadas (JWKB), comparando os resultados obtidos em cada situação. / This dissertation describes the motion of a particle in a quantum potential barrier parabolic, this system is conditionally called inverted oscillator. Determined quantum states semi-classics like family generalized coherent states (GCS), being constructed by adapting work Malkin\'s and Man\'ko, determining an operator who is integral of the motion, parameterized for some constants and recognized as annihilation operator, whose eigenstates have characteristics of squeezed states. We discuss its properties and note that it is possible to compare the GCS of inverted oscillator with GCS the particle free and harmonic oscillator obtained in the literature. Also made a study of the movement purely quantum (tunneling) in the barriers potential inverted oscillator and truncated inverted oscillator by means of exact and approximate stationary solutions (JWKB), comparing the results obtained in each situation.