Now showing items 21-40 of 676

    • Discovery of a 136 Millisecond Radio and X-Ray Pulsar in Supernova Remnant G54.1+0.3 

      Camilo, F.; Lorimer, D. R.; Bhat, N. D. R.; Gotthelf, E. V.; Halpern, J. P.; Wang, Q. D.; Lu, F. J.; Mirabal, N. (IOP, 2002-06-26)
      We report the discovery of a pulsar with period P = 136 ms and dispersion measure 308 cm⁻³ pc in a deep observation of the supernova remnant (SNR) G54.1+0.3 with the Arecibo radio telescope. Timing measurements of the new ...
    • Time-dependent Optical Spectroscopy of GRB 010222: Clues to the Gamma-Ray Burst Environment 

      Mirabal, N.; Halpern, J. P.; Kulkarni, S. R.; Castro, S.; Bloom, J. S.; Djorgovski, S. G.; Galama, T. J.; Harrison, F. A.; Frail, D. A.; Price, P. A.; Reichart, D. E.; Ebeling, H.; Bunker, A.; Dawson, S.; Dey, A.; Spinrad, H.; Stern, D. (IOP, 2002-07-01)
      We present sequential optical spectra of the afterglow of GRB 010222 obtained 1 day apart using the Low-Resolution Imaging Spectrometer (LRIS) and the Echellette Spectrograph and Imager (ESI) on the Keck Telescopes. Three ...
    • Quantum logic operations using linear optical elements 

      Franson, J.D.; Jacobs, B. C.; Pittman, T.B. (OSA Publishing, 2002-08)
      Knill, Laflamme, and Milburn [1] have shown that probabilistic quantum logic operations can be implemented using linear optical elements, such as beam splitters and phase shifters, additional photons (ancilla) and ...
    • High-Fidelity Quantum Logic Operations Using Linear Optical Elements 

      Franson, J.D.; Donegan, M. M.; Fitch, M.J.; Jacobs, B. C.; Pittman, T.B. (American Physical Society (APS), 2002-09-04)
      Knill, Laflamme, and Milburn [Nature (London) 409, 46 (2001)] have shown that quantum logic operations can be performed using linear optical elements and additional ancilla photons. Their approach is probabilistic in the ...
    • Single photons on pseudodemand from stored parametric down-conversion 

      Pittman, T.B.; Jacobs, B. C.; Franson, J.D. (American Physical Society (APS), 2002-10-10)
      We describe the results of a parametric down-conversion experiment in which the detection of one photon of a pair causes the other photon to be switched into a storage loop. The stored photon can then be switched out of ...
    • Demonstration of feed-forward control for linear optics quantum computation 

      Pittman, T.B.; Jacobs, B. C.; Franson, J.D. (American Physical Society (APS), 2002-11-14)
      One of the main requirements in linear optics quantum computing is the ability to perform single-qubit operations that are controlled by classical information fed forward from the output of single-photon detectors. These ...
    • Cyclical quantum memory for photonic qubits 

      Pittman, T.B.; Franson, J.D. (American Physical Society (APS), 2002-12-05)
      We have performed a proof-of-principle experiment in which qubits encoded in the polarization states of single photons from a parametric down-conversion source were coherently stored and read out from a quantum memory ...
    • High-Resolution Grating Spectroscopy of GRB 020405 with the Chandra Low Energy Transmission Grating Spectrometer 

      Mirabal, N.; Paerels, F.; Halpern, J. P. (IOP, 2002-12-16)
      We present high-resolution X-ray spectroscopy of GRB 020405 obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-Ray Observatory starting 1.68 days after the burst. The spectrum ...
    • Predictive Mining of Time Series Data in Astronomy 

      Perlman, Eric; Java, Akshay (2003-01-01)
      We discuss the development of a Java toolbox for astronomical time series data. Rather than using methods conventional in astronomy (e.g., power spectrum and cross-correlation analysis) we employ rule discovery techniques ...
    • Search for a Point-Source Counterpart of the Unidentified Gamma-Ray Source TeV J2032+4130 in Cygnus 

      Mukherjee, R.; Halpern, J. P.; Gotthelf, E. V.; Eracleous, M.; Mirabal, N. (IOP, 2003-02-05)
      We have made a multiwavelength study of the overlapping error boxes of the unidentified γ-ray sources TeV J2032+4130 and 3EG J2033+4118 in the direction of the Cygnus OB2 association (d = 1.7 kpc) in order to search for a ...
    • Progress in Linear Optics Quantum Computing 

      Franson, J.D.; Donegan, M. M.; Fitch, M.J.; Jacobs, B. C.; Pittman, T.B. (2003-05-09)
    • Improved single-photon detector performance 

      Fitch, M.J.; Donegan, M. M.; Jacobs, B. C.; Pittman, T.B.; Franson, J.D. (OSA Publishing, 2003-06)
      High efficiency single-photon detectors are needed for many applications including quantum cryptography and linear-optics quantum computing. We present experimental results showing improved detection efficiency of silicon ...
    • Single-photon source and quantum memory 

      Pittman, T.B.; Donegan, M. M.; Fitch, M.J.; Jacobs, B. C.; Franson, J.D. (OSA Publishing, 2003-06)
      We have experimentally demonstrated a new kind of single-photon source and a cyclical quantum memory device for photonic qubits. These initial experiments involved storage loops, active switching, and parametric down-conversion ...
    • High-Fidelity Quantum Logic Operations and Entangled Ancilla States 

      Franson, J.D.; Donegan, M. M.; Fitch, M. J.; Jacobs, B. C.; Pittman, T. B. (OSA Publishing, 2003-06)
      We describe a high-fidelity approach to linear optics quantum computing in which the quantum logic operations always produce an output. A method for generating the required entangled states is also described.
    • Quantum logic operations in optical fibers 

      Jacobs, B. C.; Fitch, M. J.; Pittman, T.B.; Franson, J.D. (OSA Publishing, 2003-06)
      We have recently demonstrated several probabilistic quantum logic operations using linear optics and post selection. Here we show how the fidelity of these devices can be increased using fibers to reduce optical mode ...
    • GRB 021004: A Possible Shell Nebula around a Wolf-Rayet Star Gamma-Ray Burst Progenitor 

      Mirabal, N.; Halpern, J. P.; Chornock, Ryan; Filippenko, Alexei V.; Terndrup, D. M.; Armstrong, E.; Kemp, J.; Thorstensen, J. R.; Tavarez, M.; Espaillat, C. (IOP, 2003-06-06)
      The rapid localization of GRB 021004 by the HETE-2 satellite allowed nearly continuous monitoring of its early optical afterglow decay, as well as high-quality optical spectra that determined a redshift of z3 = 2.328 for ...
    • Violation of Bell’s Inequality with Photons from Independent Sources 

      Pittman, T.B.; Franson, J.D. (American Physical Society (APS), 2003-06-19)
      We report a violation of Bell’s inequality using one photon from a parametric down-conversion source and a second photon from an attenuated laser beam. The two photons were entangled at a beam splitter using the postselection ...
    • Experimental controlled-NOT logic gate for single photons in the coincidence basis 

      Pittman, T. P.; Fitch, M. J.; Jacobs, B. C.; Franson, J. D. (American Physical Society (APS), 2003-09-26)
      We report a proof-of-principle demonstration of a probabilistic controlled-NOT gate for single photons. Single-photon control and target qubits were mixed with a single ancilla photon in a device constructed using only ...
    • Photon-number resolution using time-multiplexed single-photon detectors 

      Fitch, M. J.; Jacobs, B. C.; Pittman, T.B.; Franson, J.D. (American Physical Society (APS), 2003-10-10)
      Photon-number-resolving detectors are needed for a variety of applications including linear-optics quantum computing. Here we describe the use of time-multiplexing techniques that allow ordinary single-photon detectors, ...
    • Accurate Astrometry of 22 Southern Hemisphere Radio Sources 

      Fey, Alan L.; Ojha, Roopesh; Jauncey, David L.; Johnston, Kenneth J.; Reynolds, John E.; Lovell, James E. J.; Tzioumis, Anastasios K.; Quick, Jonathan F. H.; Nicolson, George D.; Ellingsen, Simon P.; McCulloch, Peter M.; Koyama, Yasuhiro (IOP, 2003-12-03)
      Milliarcsecond-accurate radio positions for 22 southern hemisphere extragalactic sources are reported. These positions are derived from Mark III very long baseline interferometry observations made between 2003 February and ...