Improved technologies for a single photon source

Recently quantum logic operations were shown to be possible without the need for nonlinear interactions between single photons. This “Linear Optics Quantum Computing” (LOQC) approach accomplishes logic operations by combining ancilla photons with target and control qubits into a carefully designed interferometer with single photon detectors determining the correct logical operations. This approach however is considered to be nondeterministic in nature i.e. the desired results only occur some fraction of the time. Amazingly the probability of a successful logic operation was shown to increase with the number N of ancilla photons provided to the system. As this number N of single photons becomes large the probability of success approaches unity. The primary challenge toward implementing such an approach is the creation of a high quality reliable source of these single photons.;The efforts of this research have been directed towards improving both the heralding efficiency and heralding rates of a high performance fiber-coupled single photon source based on an ultrafast pulsed beam-like Type-II parametric down conversion (PDC) source. Entangled photons generated from PDC are inherently broadband (many frequencies) and exit the nonlinear crystal at varying angles (different directions). This makes coupling the photons into single-mode fibers, a desirable feature for quantum computing, difficult. In response to these difficulties we have explored applying multi-layered thin film broadband anti-reflection coatings onto the ends of single-mode fibers using the technique of RF Planar Magnetron Sputtering in an effort to increase the coupling efficiency of the beam-like down converted photons. In addition, we have explored theoretically the broadband nature of novel phase matching geometries to increase heralding rates and minimize photon losses. With the ability to tailor coupling fibers to various down conversion sources we hope to increase both the heralding efficiency and heralding rate to levels needed for a broad range of future experiments.