Photonic quantum computers and communication systems

Quantum information processors have been proposed to solve classically intractable or unsolvable problems in computing, sensing, and secure communication. There has been growing interest in photonic implementations of quantum processors as they offer relatively long coherence lengths, precise state manipulation, and efficient measurement. In this thesis, we first present experimental techniques to generate on-chip, photonic quantum processors and then discuss protocols for fast and secure quantum communication. In particular, we describe how -to combine the outputs of multiple stochastic single-photon sources using a photonic integrated circuit to generate an efficient source of single photons. We then show designs for silicon-based quantum photonic processors that can be programmed to implement a large class of existing quantum algorithms and can lead to quicker testing of new algorithms than was previously possible. We will then present the integration of large numbers of highefficiency, low-timing jitter single-photon detectors onto a silicon photonic integrated circuit. To conclude, we will present a quantum key distribution protocol that uses the robust temporal degree of freedom of entangled photons to enable fast, secure key exchange, as well as experimental results for implementing key distribution protocols using silicon photonic integrated circuits. Thesis Supervisor: Dirk Englund Title: Assistant Professor