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Physics

Quantum information science

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Displaying 851 - 875 of 924

Tunable Delay of Einstein-Podolsky-Rosen Entanglement

February 18, 2009
Author(s)
Alberto M. Marino, Raphael C. Pooser, Vincent Boyer, Paul D. Lett
Entanglement is an important quantum resource which displays correlations between two subsystems that are stronger than the ones that can be obtained classically. This makes it the basis for a number of applications, such as quantum information processing

Optimization of photon pair generation in dual-element PPKTP waveguide1

January 5, 2009
Author(s)
Xiao Tang, Oliver T. Slattery, Lijun Ma
A compact scheme for high-speed frequency doubling and down-conversion on a single dual-element PPKTP waveguide is investigated. Optimal temperature is achieved and photon pair coincidence is observed at over GHz repetition rate with pulsed pump input

Building Quantum Computers

December 1, 2008
Author(s)
Emanuel H. Knill
In theory, quantum computers can be used to efficiently factor numbers, quadratically speed up many search and optimization problems, and enable currently impossible physics simulations. At first, quantum states appeared to be too fragile for implementing

Measuring intensity correlations with a two-element superconducting nanowire single-photon detector

November 24, 2008
Author(s)
Eric Dauler, Martin Stevens, Burm Baek, Richard J. Molnar, Scott A. Hamilton, Richard Mirin, Sae Woo Nam, Karl Berggren
Second-order intensity correlation measurements were made using a two-element superconducting nanowire single photon detector (SNSPD) without the need for an optical beam splitter. This approach can be used to obtain a 50-ps full width at half maximum

Josephson phase qubit circuit for the evaluation of advanced tunnel barrier materials

November 21, 2008
Author(s)
Jeffrey S. Kline, Haohua Wang, Seongshik Oh, John M. Martinis, David P. Pappas
We have found that crystalline Josephson junctions have critical current density control problems which decrease circuit yield. We present a qubit circuit designed to accommodate a factor-of-five variation in critical current density for the evaluation of

Long-distance entanglement-based quantum key distribution over optical fiber

November 10, 2008
Author(s)
Toshimori Honjo, Sae Woo Nam, Hiroki Takesue, Qiang Zhang, H. Kamada, Y. Nishida, O. Tadanaga, M. Asobe, Burm Baek, Robert Hadfield, Shigehito Miki, Mikio Fujiwara, Masahide Sasaki, Z. Wang, K. Inoue, Yoshihisa Yamamoto
We report the first entanglement-based quantum key distribution (QKD) experiment over a 100-km optical fiber. We used superconducting single photon detectors based on NbN nanowires that provide high-speed single photon detection for the 1.5-υm telecom band

Diagnosis of Pulsed Squeezing in Multiple Temporal Modes

August 26, 2008
Author(s)
Scott C. Glancy, Emanuel H. Knill, Thomas Gerrits, Tracy S. Clement, Martin J. Stevens, Sae Woo Nam, Richard P. Mirin
When one makes squeezed light by downconversion of a pulsed pump laser, many temporal / spectral modes are simultaneously squeezed by different amounts. There is no guarantee that any of these modes matches the pump or the local oscillator used to measure

Hanbury Brown-Twiss interferometry without a beamsplitter

August 19, 2008
Author(s)
Martin J. Stevens, Eric Dauler, Burm Baek, Richard J. Molnar, Scott A. Hamilton, Karl Berggren, Richard P. Mirin, Sae Woo Nam
We demonstrate Hanbury-Brown Twiss interferometry without a beamsplitter, by employing a single-mode optical fiber coupled to a multi-element superconducting nanowire single-photon detector.

Improved multiplexed Infrared Single Photon Detectors

August 11, 2008
Author(s)
Sergey V. Polyakov, Alan L. Migdall, V Schettini, Ivo P. Degiovanni, Giorgio Brida, F Piacentini
We discuss a scheme for a photon-counting detection system that overcomes the difficulties of photon-counting at high rates at telecom wavelengths. Our method uses an array of N detectors and a 1-by-N optical switch with a control circuit to direct input

Spectrally Bright and Broad Fiber-Based Heralded Single-Photon Source

July 29, 2008
Author(s)
Elizabeth A. Goldschmidt, M D. Eisaman, Jingyun Fan, Sergey V. Polyakov, Alan L. Migdall
We present the first experimental characterization of a heralded single-photon source based on spontaneous four-wave-mixing in a single-mode microstructure fiber. We measure the second-order correlation function, g(2)(0), to be far below the classical

Ultra fast quantum key distribution over a 97-km installed telecom fiber with wavelength-division-multiplexing clock synchronization

July 21, 2008
Author(s)
Akihiro Tanaka, Mikio Fujiwara, Sae Woo Nam, Yoshihiro Nambu, Seigo Takahashi, Wakako Maeda, Ken-ichiro Yoshino, Shigehito Miki, Burm Baek, Z. Wang, Akio Tajima, Masahide Sasaki, Akihisa Tomita
We demonstrated ultra fast BB84 quantum key distribution (QKD) transmission at 625 MHz clock rate through a 97 km field-installed fiber using practical clock synchronization based on wavelength-division-multiplexing (WDM). We succeeded in over-one-hour

High-efficiency, ultra-low-noise all-fiber photon pair source

June 20, 2008
Author(s)
Shellee D. Dyer, Martin J. Stevens, Burm Baek, Sae Woo Nam
We demonstrate an all-fiber photon pair source with the highest coincidence-to-accidental ratio (CAR) reported to date in the fiber optic telecom C-band. We achieve this through careful optimization of pair production efficiency as well as careful

Designing high electron mobility transistor heterostructures with quantum dots for efficient, number-resolving photon detection

May 1, 2008
Author(s)
Mary A. Rowe, Eric Gansen, M. Greene, Danna Rosenberg, Todd E. Harvey, Mark Su, Robert Hadfield, Sae Woo Nam, Richard P. Mirin
We describe the design of the epitaxial layers for an efficient, photon-number-determining detector that utilizes a layer of self-assembled quantum dots as an optically addressable gate in a field-effect transistor. Our design features a dedicated

Distribution of time-energy entanglement over 100 km fiber using superconducting single-photon detectors

April 14, 2008
Author(s)
Qiang Zhang, Hiroki Takesue, Sae Woo Nam, Carston Langrock, Xiuping Xie, Burm Baek, Martin M. Fejer, Yoshihisa Yamamoto
In this letter, we report an experimental realization of distributing entangled photon pairs over 100 km of dispersion-shifted fiber. In the experiment, we used a periodically poled lithium niobate waveguide to generate the time-energy entanglement and

An Optical Fiber-Based Source of Polarization-Entangled Photon Pairs

September 10, 2007
Author(s)
Jingyun Fan, M D. Eisaman, Alan L. Migdall
We describe an achromatic, phase-stable, broadband source of polarization-entangled photon pairs with high spectral brightness that uses four-wave mixing in a fiber Sagnac interferometer. We achieved a polarization-entangled two-photon coincidence rate of

Custom Hardware to Eliminate Bottlenecks in QKD Throughput Performance

September 5, 2007
Author(s)
Alan Mink
The National Institute of Standards and Technology (NIST) high-speed quantum key distribution (QKD) system was designed to include custom hardware to support the generation and management of gigabit data streams. As our photonics improved our software
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