Browsing by Author "Pittman, Todd B."
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Item Microcavities Using Holey Fibers(OSA Publishing, 2007) Hendrickson, Scott M.; Pittman, Todd B.; Franson, James D.Microcavities consisting of microstructured holey fibers and separate end mirrors have been constructed and tested. These devices exhibit excellent transverse-mode confinement and the ability to control the percentage of power guided outside of the fiber core. As a result, these devices may be a useful tool for enhancing the interaction between light and an atomic medium.Item Multi-Particle Interferometry Based on Double Entangled States(NASA, 2013-09) Pittman, Todd B.; Shih, Yanhua; Strekalov, D. V.; Sergienko, A. V.; Rubin, M. H.A method for producing a 4-photon entangled state based on the use of two independent pair sources is discussed. Of particular interest is that each of the pair sources produces a two-photon state which is simultaneously entangled in both polarization and space-time variables. Performing certain measurements which exploit this double entanglement provides an opportunity for verifying the recent demonstration of nonlocality by Greenberger, Horne, and Zeilinger.Item Periodic single-photon source and quantum memory(SPIE, 2004-02-03) Pittman, Todd B.; Fitch, Michael J.; Jacobs, Bryan C.; Franson, Jason M.Although there has been tremendous progress in the development of true “on-demand” single-photon sources, periodic or “pseudodemand” single-photon sources can be a sufficient resource for many optical quantum information processing applications. Here we review a recent experimental demonstration of a periodic single-photon source based on parametric down-conversion photon pairs, optical storage loops, and high-speed switching. We also review an experiment in which high speed switching and storage loops were used to implement a periodic quantum memory device for polarization-encoded single-photon qubits. Finally, we describe a method in which two of these periodic quantum memory devices are used to facilitate the production of a periodic source of entangled photon pairs. These experiments and proposals are all motivated within the context of linear optics quantum computing.Item Photon-number-resolving detection using time-multiplexing(Taylor & Francis, 2009-07-03) Achilles, Daryl; Silberhorn, Christine; Sliwa, Cezary; Banaszek, Konrad; Walmsley, Ian A.; Fitch, Michael J.; Jacobs, Bryan C.; Pittman, Todd B.; Franson, James D.Detectors that can resolve photon number are needed in many quantum information technologies. In order to be useful in quantum information processing, such detectors should be simple, easy to use, and be scalable to resolve any number of photons, as the application may require great portability such as in quantum cryptography. Here we describe the construction of a time-multiplexed detector, which uses a pair of standard avalanche photodiodes operated in Geiger mode. The detection technique is analysed theoretically and tested experimentally using a pulsed source of weak coherent light.Item Quantum Computing Using Linear Optics(THE JOHNS HOPKINS UNIVERSITY) Pittman, Todd B.; Jacobs, Bryan C.; Franson, James D.Item Simple circuit of linear optics logic gates(SPIE, 2004-10-19) Pittman, Todd B.; Jacobs, Bryan; Franson, JamesWe review an experimental demonstration of a simple irreversible circuit of two probabilistic exclusive-OR (XOR) gates for single-photon qubits. We describe the operation of the individual linear-optics gates and the overall circuit in terms of two-photon and three-photon quantum interference effects. We also discuss future plans for quantum circuits using single-photon qubits from stored parametric down-conversion sources.Item Transmission degradation and preservation for tapered optical fibers in rubidium vapor(OSA Publishing, 2013) Lai, Meimei; Franson, James D.; Pittman, Todd B.The use of subwavelength diameter tapered optical fibers (TOFs) in warm rubidium vapor has recently been identified as a promising system for realizing ultralow-power nonlinear optical effects. However, at the relatively high atomic densities needed for many of these experiments, rubidium atoms accumulating on the TOF surface can cause a significant loss of overall transmission through the fiber. Here we report direct measurements of the time scale associated with this transmission degradation for various rubidium density conditions. Transmission is affected almost immediately after the introduction of rubidium vapor into the system, and declines rapidly as the density is increased. More significantly, we show how a heating element designed to raise the TOF temperature can be used to reduce this transmission loss and dramatically extend the effective TOF transmission lifetime.Item Zeno logic gates using microcavities(OSA Publishing, 2007) Franson, James D.; Pittman, Todd B.; Jacobs, Bryan C.The linear optics approach to quantum computing has several potential advantages, but the logic operations are probabilistic. We review the use of the quantum Zeno effect to suppress the intrinsic failure events in these kinds of devices, which would produce deterministic logic operations without the need for ancilla photons or high-efficiency detectors. The potential advantages of implementing Zeno gates using microcavities and electromagnetically induced transparency are discussed.