<p><br></p><p dir="ltr">Over the past decade, optical frequency combs have spurred significant advancements in both classical ultrafast optics and quantum optics. My research contributes to these two fields, catering to applications in precision metrology and optical networking. In the domain of quantum optics, the study delves into biphoton frequency combs with time-energy entanglement, employing novel electro-optic modulation schemes to enhance sensitivity and enable precise measurements of temporal correlations. Additionally, Bell states, a crucial class of entangled quantum bases, are generated in the frequency domain, showcasing their utility in delay metrology and quantum cryptographic protocols. </p><p dir="ltr">In the realm of classical optical frequency combs, this work explores dynamic steering of pulsed optical beams, holding promise for applications in imaging and remote sensing. The concept of time-efficient dynamic beam steering using a spatial array of optical frequency combs is elucidated and experimentally demonstrated through the utilization of a high-resolution spectral disperser, specifically a virtually imaged phased array (VIPA). Furthermore, integrated photonic designs featuring wavelength-selective switches and spectral dispersers are proposed to enable a versatile on-chip implementation of the beam steering approach. In sum, this research leverages the capabilities of classical and quantum optical frequency combs, with implications for emerging applications such as distributed sensing, quantum networking, and light detection and ranging (LIDAR).</p>

<p dir="ltr">Quantum-enhanced approaches enable high-resolution imaging and sensing with signal-to-noise ratios beyond classical limits. However, operating in the quantum regime is highly susceptible to environmental influences and experimental conditions. Implementing these techniques necessitates highly controlled environments or intricate preparation methods, which can restrict their practical applications. This thesis explores the practical applications of quantum sensing, focusing on thermal sensing with bright quantum sources in biological and electronic contexts. Additionally, I discuss the development of a multimode source for quantum imaging applications and an on-chip atomic interface for scalable light-atom interactions. I built all the experimental setups from the beginning; a microscope setup for nanodiamond-based thermal sensing inside living cells, a four-wave mixing setup using a Rb cell for thermal imaging of microelectronics and multimode source, and a vacuum chamber for on-chip atomic interface.</p><p dir="ltr">Quantum sensing can be realized using atomic spins or optical photons possessing quantum information. Among these, color centers inside diamonds stand out as robust quantum spin defects (effective atomic spins), maintaining their quantum properties even in ambient conditions. In this thesis, I studied the role of an ensemble of color centers inside nanodiamonds as a probe of temperature in a living cell. Our approach involves incubating nanodiamonds in endothelial culture cells to achieve sub-kelvin sensitivity in temperature measurement. The results reveal a temperature error of 0.38 K and a sensitivity of 3.46 K/sqrt(Hz)<i> </i>after 83 seconds of measurement. Furthermore, I discuss the constraints of nanodiamond temperature sensing in living cells, propose strategies to surmount these limitations, and explore potential applications arising from such measurements.</p><p dir="ltr">Another ubiquitous quantum probe is light with quantum properties. Photons, the particles of light, can carry quantum correlations and have minimal interactions with each other and, to some extent, the environment. This capability theoretically allows for quantum-enhanced imaging or sensing of sample’s properties. In this thesis, I report on the demonstration of quantum-enhanced temperature sensing in microelectronics using bright quantum optical signals. I discuss the first demonstration of quantum thermal imaging used to identify hot spots and analyze heat transport in electronic systems.</p><p dir="ltr">To achieve this, we employed lock-in detection of thermoreflectivity, enabling us to measure temperature changes in a micro-wire induced by an electric current with an accuracy better than 0.04 degrees, averaged over 0.1 seconds. Our results demonstrate a nearly 50 % improvement in accuracy compared to using classical light at the same power, marking the first demonstration of below-shot-noise thermoreflectivity sensing. We applied this imaging technique to both aluminum and niobium-based circuits, achieving a thermal resolution of 42 mK during imaging. We scanned a 48 × 48 μm<i> </i>area with 3-4 dB squeezing compared to classical measurements. Based on these results, we infer possibility of generating a 256×256 pixel image with a temperature sensitivity of 42 mK within 10 minutes. This quantum thermoreflective imaging technique offers a more accurate method for detecting electronic hot spots and assessing heat distribution, and it may provide insights into the fundamental properties of electronic materials and superconductors.</p><p dir="ltr">In transitioning from single-mode to multimode quantum imaging, I conducted further research on techniques aimed at generating multimode quantum light. This involved an in-depth analysis of the correlation characteristics essential for utilizing quantum light sources in imaging applications. To achieve the desired multimode correlation regime, I developed a system centered on warm Rubidium vapor with nonlinear gain and feedback processes. The dynamics of optical nonlinearity in the presence of gain and feedback can lead to complexity, even chaos, in certain scenarios. Instabilities in temporal, spectral, spatial, or polarization aspects of optical fields may arise from chaotic responses within an optical <i>x</i>(2) or <i>x</i>(3) nonlinear medium positioned between two cavity mirrors or preceding a single feedback mirror. However, the complex mode dynamics, high-order correlations, and transitions to instability in such systems remain insufficiently understood.</p><p dir="ltr">In this study, we focused on a <i>x</i>(3) medium featuring an amplified four-wave mixing process, investigating noise and correlations among multiple optical modes. While individual modes displayed intensity fluctuations, we observed a reduction in relative intensity noise approaching the standard quantum limit, constrained by the camera speed. Remarkably, we recorded a relative noise reduction exceeding 20 dB and detected fourth-order intensity correlations among four spatial modes. Moreover, this process demonstrated the capability to generate over 100 distinct correlated quadruple modes.</p><p dir="ltr">In addition to conducting multimode analysis to develop a scalable imaging system, I have explored methodologies aimed at miniaturizing light-atom interactions on a chip for the scalable generation of quantum correlations. While warm atomic vapors have been utilized for generating or storing quantum correlations, they are plagued by challenges such as inhomogeneous broadening and low coherence time. Enhancing control over the velocity, location, and density of atomic gases could significantly improve light-atom interaction. Although laser cooling is a common technique for cooling and trapping atoms in a vacuum, its implementation in large-scale systems poses substantial challenges. As an alternative, I focused on developing an on-chip system integrated with atomic vapor controlled by surface acoustic waves (SAWs).</p><p dir="ltr">Surface acoustic waves are induced by an RF signal along the surface of a piezoelectric material and have already been proven to be effective for manipulating particles within microfluidic channels. Expanding upon this concept, I investigated the feasibility of employing a similar approach to manipulate atoms near the surface of a photonic circuit. The interaction between SAWs and warm atomic vapor is expected as a mechanism for controlling atomic gases in proximity to photonic chips for quantum applications. Through theoretical analysis spanning molecular dynamics and fluid dynamics regimes, I identified the experimental conditions necessary to observe acoustic wave behavior in atomic vapor. To validate this theory, I constructed an experiment comprising a vacuum chamber housing Rb atoms and a lithium niobate chip featuring interdigital transducers for launching SAWs. However, preliminary experimental results yielded no significant signals from SAW-atom interactions. Subsequent analysis revealed that observing such interactions requires sensitivity and signal-to-noise ratio (SNR) beyond the capabilities of the current setup. Multiple modifications, including increasing buffer gas pressure and mitigating RF cross-talk, are essential for conclusively observing and controlling these interactions.</p>

In this thesis I develop a formalism for analyzing quantum optics in photonic crystal slab cavities which may be coupled, lossy, and non-orthogonal. Using a tight-binding approximation I find classical coupled-cavity quasimodes which overlap in space and frequency. These classical modes are used to develop a multiphoton basis for quantum optics with non-orthogonal photon states. I develop creation and annihilation operators with a novel commutation relation as a consequence of the nonorthogonality of the quasimodes. With these operators the effective Hamiltonian, number operator, electric field operator and quadrature operators are obtained. The quantum jump technique is applied to handle the effects of loss. This technique is compared with the master equation, and conditions for the quantum jump technique being preferable are described. The quantum jump technique is implemented numerically, allowing for time-dependent linear and X(2) non-linear pumping. I use a combination of analytic results and characteristic functions to examine the evolution of coherent and squeezed states in a single lossy quasimode. The analysis is then extended to two nonorthogonal quasimodes. States are investigated using reduced characteristic functions. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2013-09-27 12:00:10.281

The algebra of SU(2) is ubiquitous in physics, applicable both to the atomic spin states and the polarisation states of light. The method developed by Majorana and Schwinger to represent pure, symmetric spin-states of arbitrary value as a product of spin-1/2 states is a powerful tool that allows for a great conceptual and practical simplification. Foremost, it allows the representation of a qudit on the same geometry as a qubit, i.e., the Bloch sphere. An experimental implementation of the Majorana representation in the realm of quantum optics is presented. The technique allows the projection of arbitrary quantum states from a coherent state input. It is also shown that the method can be used to synthesise arbitrary interference patterns with unit visibility, and without resorting to quantum resources. In this context, it is argued that neither the shape nor the visibility of the interference pattern is a good measure of quantumness. It is only the measurement scheme that allows for the perceived quantum behaviour. The Majorana representation also proves useful in delineating uncertainty limits of states with a particular spin value. Issues with traditional uncertainty relations involving the SU(2) operators, such as trivial bounds for certain states and non-invariance, are thereby resolved with the presented pictorial solution. / <p>QC 20170428</p>

Apresentamos neste trabalho o projeto e a construção de um Oscilador Paramétrico Ótico (OPO), demonstrando o caráter quântico da correlação de intensidade dos feixes sinal e complementar nele produzidos a partir de um feixe de bombeio de 532 nm. Estudamos ainda a compressão quântica de ruído no feixe de bombeio refletido por uma cavidade de OPO, obtendo 38 % de redução (abaixo do limite quântico) no ruído de quadratura de um feixe de 1064 nm produzido por um laser de Nd:YAG. Por fim, observamos a formação de estruturas nos feixes de saída para cavidades com modos transversos degenerados (confocal e concêntrica) e demonstramos pela primeira vez o caráter multimodo transverso das correlações quânticas em um OPO com cavidade confocal. / We present in this work the project and construction of an Optical Parametric Oscillator (OPO), showing the quantum behavior in the intensity correlation of signal and idler beams, generated from a 532 nm pump. We have also studied the quantum noise compression in the pump beam reflected from an OPO cavity, obtaining 38 % of noise reduction below the vacuum fluctuations in the quadrature of a 1064 nm beam coming from a Nd:YAG laser. Finally, we observed the pattern formation in the output beams for transverse degenerate cavities (confocal and concentric) and we show, for the first time to our knowledge, the transverse multimode behavior in the quantum correlation of a confocal OPO.

Estudamos teoricamente a geração de estados emaranhados do campo eletromagnético através do processo de mistura de quatro ondas em uma nuvem de átomos frios em configuração duplo- trabalhando perto da ressonância. Mostra-se que neste caso é possível gerar emaranhamento com uma potência de bombeio muito menor do que na situação em que temos átomos quentes [17]. Baseando-se nos parâmetros da armadilha de átomos de rubídio de nosso laboratório, calcula-se uma violação de 46.5 % do limite imposto pela desigualdade DGCZ [59] para uma frequência de Rabi dos bombeios de =0.8 MHz (neste caso, equivalente a uma potência de 0.3 µW) e uma dessintonia de =20 MHz para uma transição enquanto a outra permanece ressonante. Também foi analisado o emaranhamento entre as bandas laterais dos feixes de prova e conjugado, estudando a estrutura do emaranhamento entre estes quatro modos através do critério positividade sobre transposição parcial em variáveis continuas. Nesta análise, se observaram correlações quânticas entre pares de campos (a banda superior do feixe de prova e a banda inferior do feixe conjugado, e a banda inferior do feixe de prova e a banda superior do feixe conjugado). Estas evidências, junto com as equações de evolução dos feixes, sugerem que a mistura de quatro ondas, dentro das considerações supostas neste trabalho, gera estados nos quais o emaranhamento é exclusivo entre as bandas laterais superior de um feixe com a inferior do outro. [17] Vincent Boyer et al. Science, 321-544 (2008). [59] Lu-Ming Duan et al. Phys. Rev. Lett 84-2722 (2000) / We have theoretically studied the generation of entangled states of the electromagnetic field through the four wave mixing (FWM) process in a cold atomic cloud in a double-, close to resonance configuration. It is shown that in this case it possible to generate entanglement with a pump power much weaker than in the situation which we have hot atoms [17]. Based in the parameters obtained in the magneto-optical trap (MOT) with rubidium at our laboratory, we calculated a violation of 46.5 % of the limit imposed by the DGCZ inequality [59] at a Rabi frequency of the pump fields of =0.8 MHz (in this case, this is equivalent to a pump power of 0.3 µW) and a detuning of =20 MHz in one of the transition, while the other one remains resonant. We also analysed the entanglement between the side bands of the probe and conjugate beams. Using the positive partial transpose criterion in continuous variables, we studied the structure of entanglement within these side bands. In this analysis we observed quantum correlations between pairs of fields (the upper side band of the probe beam with the lower side band of the conjugate beam, and the lower side band of the probe beam with the upper side band of the conjugate beam). These evidences, together with the evolution equations of the beams, suggest that the 4WM process, within the considerations made in this work, generates states where the entanglement is exclusive between the upper side band of one beam and the lower side band of the other. [17] Vincent Boyer et al. Science, 321-544 (2008). [59] Lu-Ming Duan et al. Phys. Rev. Lett 84-2722 (2000).

L'objectif de ce projet de thèse est de mettre en évidence des phénomènes de chiralité optique induits dans des systèmes plasmoniques. La manipulation des différents degrés de liberté de la lumière est mise en évidence par le biais de techniques expérimentales complémentaires basées sur la tomographie en polarisation, la microscopie à fuites radiatives et la microscopie en champ proche optique (SNOM). D'une part, nous rapportons une méthode de caractérisation non-invasive afin de révéler la présence conjointe de chiralité planaire et volumique au sein de métasurfaces plasmoniques. Pour décrire cette chiralité mixte, une généralisation du modèle de Kuhn est développée. D'autre part, nous démontrons deux dispositifs plasmoniques exploitant le couplage spin-orbite optique pour contrôler les moments angulaires de spin et orbitaux de la lumière. En particulier, le mécanisme réciproque de l'effet spin Hall optique est démontré à l'aide de nano-ouvertures en forme de T: la trajectoire des plasmons de surface est adressée dans le moment angulaire de spin des photons. Cette fonctionnalité est ensuite mise en œuvre dans une expérience de brouillage d'interférence. La génération de vortex plasmoniques est également réalisée par le biais de cavités spirales, dont la chiralité conditionne l'intensité et le moment angulaire orbital des vortex. Enfin, une preuve de concept sur la mesure de la densité locale d’états optique, façonnée par un environnement chiral, est démontrée à l'aide d'une sonde SNOM classique et quantique. Ce travail permet de connecter les grandeurs de densité et de flux de chiralité aux interactions lumière-matière. L'étude de la chiralité dans le contexte de la plasmonique ouvre des perspectives prometteuses dans la nano-manipulation optique, la séparation de molécules chirales et le contrôle de sources quantiques. / In this thesis, we aim at demonstrating chiral optical effects in plasmonic systems. The manipulation of the different degrees of freedom of light is evidenced by complementary experimental approaches based on polarisation tomography, leakage radiation microscopy and scanning near-field optical microscopy (SNOM). On one hand, we report on a non-invasive method to reveal the coexistence of surface and bulk chirality in plasmonic metasurfaces. Specifically, we extend the model of Kuhn to describe this chirality mixture. On the other hand, we demonstrate two plasmonic devices which rely on the optical spin-orbit coupling to control the spin and the orbital angular momentum of light. In particular, the reciprocal mechanism of the spin-Hall effect of light is shown using T-shaped nano-apertures: the trajectory of surface plasmons can be encoded in the spin of the photons. This which-path marker is then implemented in an interference erazer experiment. Plasmonic vortex generation is also reported in spiral cavities. The spiral chirality rules the intensity as well as the angular orbital momentum of the singular fields. Finally, as a proof of concept, we demonstrate using a conventional and quantum SNOM probe that the local density of optical states can be structured by a chiral environment. We also connect the density and flux chirality to light-matter interactions. Studying chirality in the context of plasmonics opens promising prospects in the optical nano-manipulation, chiral molecules discrimination and the control of quantum sources.

Tem-se como intuito desse projeto a construção e o desenvolvimento de um Hamiltoniano intensity dependent, cuja interação entre radiação-matéria dependa do número de fótons que residem dentro da cavidade do laser. O Hamiltoniano de Jaynes Cummings é tradicionalmente conhecido por descrever a interação radiação-matéria, e através de uma modificação efetuada no mesmo, criando um Hamiltoniano não-linear em termos dos operadores de criação e aniquilação, pretende-se obter uma nova distribuição do número de fótons dentro de tal cavidade, bem como uma nova estatística em relação ao modelo usual de laser. Para tal,faz-se uso de um modelo de átomo de dois níveis para a descrição da matéria dentro da cavidade, bem como conhecimentos de informação e óptica quântica para o desenvolvimento e análise dos resultados obtidos, como o fator Q de Mandel, juntamente com aplicações de Hamiltonianos não lineares, necessários para o entendimento do projeto. Finalmente, discute-se as consequências da nova distribuição; suas semelhanças e suas diferenças em relação à tradicional, focando nos papéis dos parâmetros do laser. / The purpose of this work is the construction and development of an intensity dependent Hamiltonian, whose interaction between radiation and matter depends on the photon number inside the laser cavity. The Jaynes Cummings\'s Hamiltonian is traditionally known because of its description of the radiation-matter interaction, and through a modification on this hamiltonian, building a non-linear hamiltonian in terms of the creation and anihilation operators, we intend to obtain a new distribuition of the photon number inside the laser cavity, as well as a new statistics regarding the usual laser model. In order to do it, we use two levels atom model to describe the matter inside the cavity, as well as knowledge of quantum optical and quantum information to develop and analyze the obtained results, like the Mandel Q parameter, along with the non-linear hamiltonian applications, necessary to understand this project. Finally, we discuss the consequences of its new distribution, its similarities and diferences about the traditionals, focusing on the roles of the laser parameters.

Apresentamos neste trabalho o projeto e a construção de um Oscilador Paramétrico Ótico (OPO), demonstrando o caráter quântico da correlação de intensidade dos feixes sinal e complementar nele produzidos a partir de um feixe de bombeio de 532 nm. Estudamos ainda a compressão quântica de ruído no feixe de bombeio refletido por uma cavidade de OPO, obtendo 38 % de redução (abaixo do limite quântico) no ruído de quadratura de um feixe de 1064 nm produzido por um laser de Nd:YAG. Por fim, observamos a formação de estruturas nos feixes de saída para cavidades com modos transversos degenerados (confocal e concêntrica) e demonstramos pela primeira vez o caráter multimodo transverso das correlações quânticas em um OPO com cavidade confocal. / We present in this work the project and construction of an Optical Parametric Oscillator (OPO), showing the quantum behavior in the intensity correlation of signal and idler beams, generated from a 532 nm pump. We have also studied the quantum noise compression in the pump beam reflected from an OPO cavity, obtaining 38 % of noise reduction below the vacuum fluctuations in the quadrature of a 1064 nm beam coming from a Nd:YAG laser. Finally, we observed the pattern formation in the output beams for transverse degenerate cavities (confocal and concentric) and we show, for the first time to our knowledge, the transverse multimode behavior in the quantum correlation of a confocal OPO.

Cette thèse de doctorat en co-tutelle a été centrée sur des expériences d’optique quantique faisant intervenir de grands ensembles atomiques. L’étude de l’interaction entre la lumière et la matière et l’augmentation de leur couplage dans ces systèmes sont des étapes fondamentales pour le développement et l’amélioration de protocoles de génération, de stockage et de manipulation d’information quantique. Le travail de thèse exposé ici traite en particulier de l’évolution des techniques de préparation d’ensembles atomiques denses, des protocoles de lumière arrêtée et de lumière stationnaire développés et étudiés expérimentalement. Les ensembles d’atomes froids préparés par refroidissement laser dans les deux réalisations expérimentales ont été portés jusqu’à des épaisseurs optiques de plusieurs centaines, à des températures d’une dizaine de microkelvin. De plus, l’adressage de ces ensembles dans des configurations symétriques ont permis l’étude de protocoles basés sur le renversement temporel de la conversion de lumière en excitations atomiques collectives. Ces améliorations ont mené au stockage de bits quantiques par transparence induite électromagnétiquement, et de lumière cohérente par symétrie temporelle dans une mémoire Raman, tous deux à des record d’efficacité, à de plus de 50%. Ce travail a également conduit à l’étude expérimentale de la lumière stationnaire et de nouveaux protocoles en découlant. / This cotutelle PhD thesis revolves around quantum optics experiments which involve large atomic ensembles. The study of light-matter interaction and its enhancement are crucial steps in the development and progress of quantum information generation, storage and processing protocols. The work presented here focuses on the evolution of large atomic ensemble preparation techniques, on the development and experimental investigation of stopped and stationary light protocols. Laser-cooled atomic ensembles in both experimental realisations have been brought to optical depths of a few hundreds, at temperatures of tens of microkelvin. Moreover, addressing these ensembles in symmetric configurations has enabled the study of protocols based on the temporal reversal of the mapping of light to collective atomic excitations. These enhancements have led to the storage of qubits based on electromagnetically-induced transparency, and the optical storage in a backward-retrieval Raman scheme, both demonstrating efficiency records, above 50%. This work has also led to the experimental investigation of stationary light and new protocols based on it.