An optomechanical system consists of an optical cavity coupled to a mechanical oscillator. The system used for this work was a silica microsphere. In a silica microsphere, the optical cavity is formed by light that is confined by total internal reflection while circulating around the equator of the sphere. The mechanical oscillator is the mechanical breathing motion of the sphere itself. The optical cavity and mechanical oscillator are coupled by radiation pressure and by the mechanical oscillator physically changing the length of the optical cavity. The optomechanical analog to electromagnetically induced transparency (EIT), known as optomechanically induced transparency (OMIT), has previously been studied in its steady state. One topic of this dissertation is an experimental study of OMIT in the time domain. The results of these experimental demonstrations continue comparisons between EIT and OMIT, while also building a foundation for optomechanical light storage. In OMIT, an off-resonance control laser controls the interaction between on-resonance light and the mechanical oscillator. Optomechanical light storage makes use of this arrangement to store an optical signal as a mechanical excitation, which is then retrieved at a later time as an optical signal. This is done by using two temporally separated off-resonance control laser pulses. This technique is extremely flexible in frequency and displays a storage lifetime on the order of microseconds. Use of optomechanical systems for quantum mechanical applications is hindered by the thermal background noise of the mechanical oscillator. Addressing this issue by first cooling the mechanical oscillator is costly and fraught with difficulties. The final topic presented in this dissertation deals with this issue through the use of an optomechanical dark mode. Two optical modes can interact with the same mechanical mode. The dark mode is a state that couples the two optical modes but is decoupled from the mechanical oscillator. While our specific optomechanical system is limited by its somewhat modest optomechanical cooperativity, this conversion process can, in principle, preserve the quantum state of the signal, even at room temperature, opening the possibility for this technique to be applied in quantum information processing.

Modern fiber-optic networks leverage massive parallelization of communications channels in the spectral domain, as well as low-noise recovery of optical signals, to achieve high rates of information transfer. However, quantum information imposes additional constraints on optical transport networks – the no-cloning theorem forbids use of signal regeneration and many network protocols are premised on operations like Bell state measurements that prize spectral indistinguishability. Consequently, a key challenge for quantum networks is identifying a path to high-rate and high-fidelity quantum state transport.<div><br></div><div>To bridge this gap between the capabilities of classical and quantum networks, we developed techniques that harness spectral multiplexing of quantum channels, as well as that support frequency encoding. In relation to the former, we demonstrated reconfigurable connectivity over arbitrary subgraphs in a multi-user quantum network. In particular, through flexible provisioning of the pair source bandwidth, we adjusted the rate at which entanglement was distributed over any user-to-user link. To facilitate networking protocols compatible with both spectral multiplexing and frequency encoding, we synthesized a Bell state analyzer based on mixing outcomes that populate different spectral modes, in contrast to conventional approaches that are based on mixing outcomes that populate different spatial paths. This advance breaks the tradeoff between the fidelity of remote entanglement and the spectral distinguishability of photons participating in a joint measurement.<br></div><div><br></div><div>Finally, we take steps toward field deployment by developing photonic integrated circuits to migrate the aforementioned functionality to a chip-scale platform while also achieving the low loss transmission and high-fidelity operation needed for practical quantum networks.<br></div>

Ce manuscrit expose le développement de ressources fondamentales pour les communications quantiques à longues distances basées sur les technologies des fibres optiques télécoms et des guides d'onde optiques non linéaires. Après une introduction générale sur les communications quantiques, cette thèse est structurée en trois parties principales. La première partie illustre le développement de deux sources pour la génération de paires de photons intriqués en polarisation et émis à une longueur d'onde télécom via conversion paramétrique spontanée (SPDC) dans des guides d'ondes non linéaires intégrés sur niobate de lithium périodiquement polarisé. Les sources s'appuient respectivement sur un accord de phase de type-II et un accord de phase de type-0 et sur des solutions de filtrage et d'interférométrie mises en place après le cristal non linéaire. Dans la seconde partie, sont discutées les réalisations de deux sources de photons uniques annoncés haut débit. La première s'appuie sur le multiplexage spatial sur puce de photons uniques annoncés. La seconde exploite le multiplexage temporel passif grâce à l'utilisation d'un laser télécom cadencé à 10 GHz. Enfin, nous présentons une approche tout-optique visant la synchronisation de sources distantes de paires de photons intriqués, agencées selon une architecture de type relais quantique distribué. Cette technique innovante repose sur l'utilisation d'un laser télécom impulsionnel en tant qu'horloge optique de référence. Cette horloge autorise la synchronisation de l'émission de paires de photons dans la bande C des télécoms en deux lieux distants. Des résultats préliminaires d'interférence à deux photons sont montrés et discutés. / This manuscript reports the development of fundamental resources for long distance quantum communication based on fibre telecom technology and non-linear optical waveguides. After a general introduction on quantum communication, the thesis is structured along three parts. The first part illustrates the development of two photonic polarization entanglement sources suitable for quantum networking. Both sources generate paired photons at telecom wavelength via spontaneous parametric down conversion (SPDC) in periodically poled lithium niobate waveguides (PPLN/W). They rely on type-II and type 0 phase matching, respectively. In the second part, two high quality heralded single photon sources are highlighted. The first one relies on on-chip generation and spatial multiplexing of heralded single photons towards achieving higher bit rates. The second one takes advantage of passive temporal multiplexing of a single SPDC process. Finally, an all-optical approach towards efficient and accurate synchronization of remote entangled photon pair sources within quantum relay architecture over long distances is presented. This particular synchronization technique highlights the use of ultra-fast picosecond pulsed telecom fiber laser, operating at 2.5 GHz repetition rate, acting as a master optical clock, enabling to accurately synchronize the emission of photon pairs in the telecom C-band of wavelengths at two remote locations. This innovative approach is applied for synchronizing two remote PLLN/W based sources operated at 2.5 GHz, and preliminary results on two-photon interference obtained with single photons coming from each source are shown and discussed.