Emergence, engineering and characterization of nonclassical states of light.
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Date
2026
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Universidad de Concepción
Abstract
Los estados no-clásicos de la luz constituyen un recuros fundamental para las tecnologías cuánticas. Entender como emergen, como pueden ser generados de manera controlada y como pueden ser caracterizados de manera eficiente es aún un desafío central en el área de la óptica cuántica de variable contínua. Esta tesis trata estos aspectos dentro de un marco teórico unificado. Primeramente estudiamos la emergencia de la no-clasicalidad inducida por un Hamiltoniano no lineal en el número de fotones. Considerando la evolución de estados coherentes bajo esta interacción no-lineal, demostramos la aparición universal de características no Gausianas y caracterizamos los estados cuánticos resultantes a través de medidas de no-clasicalidad complementarias, incluyendo la negatividad de la función de Wigner y la información cuántica de Fisher. A continuación, nos enfocamos en la generación controlada de estados noclásicos por medio de un Hamiltoniano tipo Kerr forzado por un campo coherente. En este contexto, evidenciamos la generación determinista de los photon added coherent states. Para caracterizar este proceso de caracterización, introducimos la cantidad de número de fotones remanente, la cual identifica la formación de estos estados durante la evolución y a la vez revela sus características no clásicas. Finalmente, proponemos protocolos de tomografía de estados cuánticos para campos propagantes basados en metasuperficies cuánticas o espejos cuánticos, interfaces ópticas cuya reflectividad está controlada por el estado cuántico de un átomo auxiliar. Al explotar la respuesta óptica condicional de estas interfaces luz–materia, los esquemas propuestos permiten reconstruir funciones de onda y distribuciones de cuasiprobabilidad en el espacio de fases mediante mediciones indirectas sobre un sistema auxiliar de variables discretas. Estos protocolos proporcionan alternativas experimentalmente viables a la tomografía homodina convencional y, a la vez, presentan robustez frente a fluctuaciones de fase óptica. En conjunto, esta tesis establece un enfoque unificado para el estudio de la emergencia, generación y caracterización de estados no clásicos de la luz, combinando la dinámica cuántica no-lineal con nuevos métodos tomográficos para sistemas cuánticos de variables continuas.
Nonclassical states of light constitute fundamental resources for quantum technologies. Understanding how they emerge, how they can be generated in a controlled manner, and how they can be efficiently characterized remains a central challenge in continuous-variable quantum optics. This thesis addresses these aspects within a unified theoretical framework. We first study the emergence of nonclassicality induced by photon-number dependent nonlinear Hamiltonians. Considering the evolution of coherent states under these nonlinear interactions, we demonstrate the universal appearance of non-Gaussian features and characterize the resulting quantum states through complementary measures of nonclassicality, including Wigner-function negativity and quantum Fisher information. We then focus on the controlled generation of nonclassical states by considering a Kerr Hamiltonian driven by a coherent field. Within this framework, we demonstrate the deterministic generation of photon added coherent states. To characterize this generation process, we introduce the remnant photon number witness, which identifies the formation of these states during the evolution while simultaneously revealing their nonclassical character. Finally, we develop quantum state tomography protocols for propagating continuous-variable states based on quantum metasurfaces or quantum mirrors– optical interfaces with switchable reflectivity controlled by the quantum state of an ancillary atom. Exploiting the conditional optical response of these light-matter interfaces, the proposed schemes enable the reconstruction of wavefunctions and phase-space quasiprobability distributions through indirect measurements on an ancillary discrete-variable system. These protocols provide experimentally feasible alternatives to conventional homodyne tomography while exhibiting robustness against optical phase fluctuations. Overall, this thesis establishes a unified approach to the emergence, generation, and characterization of nonclassical states of light, combining nonlinear quantum dynamics with novel tomographic methods for continuous-variable quantum systems.
Nonclassical states of light constitute fundamental resources for quantum technologies. Understanding how they emerge, how they can be generated in a controlled manner, and how they can be efficiently characterized remains a central challenge in continuous-variable quantum optics. This thesis addresses these aspects within a unified theoretical framework. We first study the emergence of nonclassicality induced by photon-number dependent nonlinear Hamiltonians. Considering the evolution of coherent states under these nonlinear interactions, we demonstrate the universal appearance of non-Gaussian features and characterize the resulting quantum states through complementary measures of nonclassicality, including Wigner-function negativity and quantum Fisher information. We then focus on the controlled generation of nonclassical states by considering a Kerr Hamiltonian driven by a coherent field. Within this framework, we demonstrate the deterministic generation of photon added coherent states. To characterize this generation process, we introduce the remnant photon number witness, which identifies the formation of these states during the evolution while simultaneously revealing their nonclassical character. Finally, we develop quantum state tomography protocols for propagating continuous-variable states based on quantum metasurfaces or quantum mirrors– optical interfaces with switchable reflectivity controlled by the quantum state of an ancillary atom. Exploiting the conditional optical response of these light-matter interfaces, the proposed schemes enable the reconstruction of wavefunctions and phase-space quasiprobability distributions through indirect measurements on an ancillary discrete-variable system. These protocols provide experimentally feasible alternatives to conventional homodyne tomography while exhibiting robustness against optical phase fluctuations. Overall, this thesis establishes a unified approach to the emergence, generation, and characterization of nonclassical states of light, combining nonlinear quantum dynamics with novel tomographic methods for continuous-variable quantum systems.
Description
Tesis presentada para optar al grado de Doctor/a en Ciencias con mención en Óptica Cuántica.
Keywords
Quantum optics, Tomography, Photons, Light