Now showing items 21-40 of 895

    • The Next Geminga: Deep Multiwavelength Observations of a Neutron Star Identified with 3EG J1835+5918 

      Halpern, J. P.; Gotthelf, E. V.; Mirabal, N.; Camilo, F. (IOP, 2002-06-02)
      We describe Chandra, Hubble Space Telescope (HST), and radio observations that reveal a radio-quiet but magnetospherically active neutron star in the error circle of the high-energy γ-ray source 3EG J1835+5918, the brightest ...
    • Demonstration of Nondeterministic Quantum Logic Operations Using Linear Optical Elements 

      Pittman, T. P.; Jacobs, B. C.; Franson, J.D. (American Physical Society (APS), 2002-06-06)
      Knill, Laflamme, and Milburn [Nature (London) 409, 46 (2001)] recently showed that nondeterministic quantum logic operations could be performed using linear optical elements, additional photons (ancilla), and postselection ...
    • The 2001 Superoutburst of WZ Sagittae 

      Patterson, Joseph; Masi, Gianluca; Richmond, Michael W.; Martin, Brian; Beshore, Edward; Skillman, David R.; Kemp, Jonathan; Vanmunster, Tonny; Rea, Robert; Allen, William; Davis, Stacey; Davis, Tracy; Henden, Arne A.; Starkey, Donn; Foote, Jerry; Oksanen, Arto; Cook, Lewis M.; Fried, Robert E.; Husar, Dieter; Novák, Rudolf; Campbell, Tut; Robertson, Jeff; Krajci, Thomas; Pavlenko, Elena; Mirabal, Nestor; Niarchos, Panos G.; Brettman, Orville; Walker, Stan (IOP, 2002-06-10)
      We report the results of a worldwide campaign to observe WZ Sagittae during its 2001 superoutburst. After a 23 yr slumber at V = 15.5, the star rose within 2 days to a peak brightness of 8.2, and showed a main eruption ...
    • 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 ...
    • Measuring the relativistic perigee advance with Satellite Laser Ranging 

      Iorio, Lorenzo; Ciufolini, Ignazio; Pavlis, Erricos C. (IOP, 2002-07-30)
      The pericentric advance of a test body by a central mass is one of the classical tests of general relativity. Today, this effect is measured with radar ranging by the perihelion shift of Mercury and other planets in the ...
    • 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 ...
    • Atmospheric Refraction at Optical Wavelengths: Problems and Solutions 

      Mendes, V. B.; Pavlis, E.C. (NASA, 2002-10)
      Atmospheric refraction is an important accuracy-limiting factor in the application of satellite laser ranging (SLR) to high-accuracy applications. The modeling of that source of error in the analysis of SLR data comprises ...
    • 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 ...
    • European radar altimeter calibration and sea-level monitoring site for Jason-1 and Envisat at the island of Gavdos, Crete, Greece 

      Mertikas, Stelios P.; Pavlis, Erricos C.; Drakopoulos, Panos; Palamartchouk, Kirill (SPIE, 2003-02-14)
      An absolute sea level monitoring and altimeter calibration permanent facility is being established on the isle of Gavdos, south of the island of Crete, Greece. This calibration facility has been chosen because Gavdos is ...
    • 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.