Modeling and Experimental Observation of Hong-Ou-Mandel Interference Towards Quantum Teleportation

Abstract This dissertation investigates the generation and experimental study of photon pairs pro- duced via spontaneous parametric down-conversion (SPDC), using a sophisticated optical system designed for high-precision quantum optics research. Central to our approach is the MIRA 900 laser, a flexible and tunable femtosecond pulsed laser used to produce photon pairs through SPDC in a nonlinear crystal. While the employed Sagnac interferometer is capable of generating polarization-entangled photon pairs, for the purpose of Hong-Ou-Mandel (HOM) interference measurements presented in this work, the source was configured to emit separable states (e.g., HH) to ensure maximum indistinguishability at the beam splitter. The interferometer’s stability and phase insensitivity, along with polarization-maintaining fibers and adjustable opti- cal delay lines, were essential for achieving precise temporal overlap between the photon pairs—a critical condition for observing the HOM effect. To improve the accuracy of quantum interference measurements, we evaluated several types of photon detectors, including SPD OEM NIR, PDM-IR, and superconducting nanowire single-photon detectors (SNSPDs). Among these, SNSPDs demonstrated the best performance due to their extremely low background noise and high timing precision, both of which are crucial for accurate coincidence detection. Further enhancements were achieved by incorporating a periodically poled potas- sium titanyl phosphate (PPKTP) waveguide crystal, which significantly improved phase- matching efficiency and photon pair generation rates. Additionally, narrowband spectral filters were used to enhance coherence and HOM interference visibility under specific experimental conditions. The results of this study emphasize the importance of precise wavelength selection, timing synchronization, and optimized detection in advancing quantum technologies. These findings have significant implications for quantum communication, quantum key distribution (QKD), and photonic quantum computing.