We propose two interesting methods of generating the four-photon W state. These methods use parametric down-conversion processes, linear optical elements, and commercial photon detectors, which are readily feasible un...
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We propose two interesting methods of generating the four-photon W state. These methods use parametric down-conversion processes, linear optical elements, and commercial photon detectors, which are readily feasible under current technology. They can also be used to generate the three-photon W state, the three-photon Greenberger-Horne-Zeilinger state, and the three-photon maximally entangled photon-number state (a typical photon-number entanglement state) by simply changing some experimental components or their parameters. Moreover, assuming we have photon number-resolving detectors, these methods can develop into methods that generate a general n-photon W state. They are expected to become powerful tools for experimental investigations of multipartite entanglement and its applications to quantum information processing.
An experimental scheme for producing a four-photon entangled W state directly from the parametric down-conversion of a two-crystal geometry is proposed. In our scheme, only linear optical elements and photon detectors...
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An experimental scheme for producing a four-photon entangled W state directly from the parametric down-conversion of a two-crystal geometry is proposed. In our scheme, only linear optical elements and photon detectors are required. Sophisticated and fragile interferometric setups are unnecessary.
We report the generation of polarization-entangled photons by cavity-enhanced spontaneous parametric down-conversion. The bandwidth of entangled photons is reduced to that of the optical parometric oscillator and the ...
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We report the generation of polarization-entangled photons by cavity-enhanced spontaneous parametric down-conversion. The bandwidth of entangled photons is reduced to that of the optical parometric oscillator and the conversion rate is enhanced by cavity. The time interval between the conjugate two photon is prolongated so that it can be directly measured by a common detector. The time correlation function of the entangled-photons pair shows a time-oscillatory characteristic. To demonstrate the entanglement, we experimentally obtain two-photon quantum interference for the polarization variable.
Quantum spectroscopy was performed using the frequency-entangled broadband photon pairs generated by spontaneous parametric down-conversion. An absorptive sample was placed in front of the idler photon detector, and t...
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Quantum spectroscopy was performed using the frequency-entangled broadband photon pairs generated by spontaneous parametric down-conversion. An absorptive sample was placed in front of the idler photon detector, and the frequency of signal photons was resolved by a diffraction grating. The absorption spectrum of the sample was measured by counting the coincidences, and the result is in agreement with the one measured by a conventional spectrophotometer with a classical light source.
In this paper, a four-photon entangled state obtained directly from the down-conversion of a two-crystal geometry is analyzed. These two identically cut type-I crystals are oriented with their optic axes aligned in pe...
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In this paper, a four-photon entangled state obtained directly from the down-conversion of a two-crystal geometry is analyzed. These two identically cut type-I crystals are oriented with their optic axes aligned in perpendicular planes. The applications of this kind of four-photon entangled state are also discussed.
Two-photon interference of multimode two-photon pairs produced by an optical parametric oscillator has been observed with an unbalanced interferometer. The time correlation between the multimode two photons has a mult...
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Two-photon interference of multimode two-photon pairs produced by an optical parametric oscillator has been observed with an unbalanced interferometer. The time correlation between the multimode two photons has a multipeaked structure. This property of the multimode two-photon state induces two-photon interference depending on the delay time.
作者：
Y. G. ChenM. OguraH. OkushiDiamond Research Center
National Institute of Advanced Industrial Science and Technology (AIST) and Core Research for Evolutional Science and Technology of Japan Science and Technology Corporation (CREST JST) Umezono 1-1-1 Tsukuba 305-8568 Japan
Experiments of annealing effect of boron-doped homoepitaxial diamond film on Schottky junction properties have been conducted to investigate the origin of the “pinning” states in oxidized surface of diamond. Metals ...
Experiments of annealing effect of boron-doped homoepitaxial diamond film on Schottky junction properties have been conducted to investigate the origin of the “pinning” states in oxidized surface of diamond. Metals of Al, Ni, Au, and Pt are evaporated onto boron-doped diamond films with post thermal annealing less than 800 °C or higher than 900 °C. The current–voltage (I–V) characteristics of Schottky junctions for low-temperature annealing show excellent rectification behavior, indicating the existence of the “pinning” states. After high-temperature annealing, the I–V curves show worse rectification or ohmic properties depending on the metal work function, suggesting the decrement of the density of “pinning” state. Capacitance–voltage measurements for the Schottky diodes show the strong thermal annealing effects on surface region property of the diamond film only after high temperature annealing. A possible explanation is the oxygen-related “pinning” states existing in the oxidized-surface of diamond are annealed out partially during high temperature annealing.
All-optical switching and wide-range wavelength conversion have been demonstrated at 160 Gbit/s using four-wave mixing in a semiconductor optical amplifier. We used the asymmetrical multiple-quantum-well semiconductor...
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All-optical switching and wide-range wavelength conversion have been demonstrated at 160 Gbit/s using four-wave mixing in a semiconductor optical amplifier. We used the asymmetrical multiple-quantum-well semiconductor optical amplifier which allows for a wide 3 dB gain-bandwidth. The cross-correlation measurements show the high-speed switching capability for wavelength routing in optical time division multiplexing networks.
Theta rhythm dependent activity of rat hippocampal cells "theta phase precession" was elucidated based on the hypothesis that theta phase coding enables instantaneous acquisition of experienced events. By us...
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Theta rhythm dependent activity of rat hippocampal cells "theta phase precession" was elucidated based on the hypothesis that theta phase coding enables instantaneous acquisition of experienced events. By using a neural network model of theta phase coding we demonstrate high acquisition abilities of spatial and temporal events. A theoretical prerequisite for this computational power predicts a hippocampal-entorhinal network mechanism to regulate theta phase coding.
We study the magnetoresistance Rxx, and the Hall resistance Rxy in GaAs/AlxGa1−xAs/GaAs bilayer systems, in which the electron channel of each layer is latterally confined in a narrow Hall bar of width W=0.3–5μm. We...
We study the magnetoresistance Rxx, and the Hall resistance Rxy in GaAs/AlxGa1−xAs/GaAs bilayer systems, in which the electron channel of each layer is latterally confined in a narrow Hall bar of width W=0.3–5μm. We observe that intralayer backscattering destroy some states peculiar to the bilayer system. Rxy plateaus at odd filling factors largely deviate from their integer values in monolayer quantum Hall (QH) states due to backscattering, while the normal Rxy plateau is observed from coupled QH states. Examining the backscattering both in the Hall bars and in their voltage probes, we discuss the suppression of the intralayer backscattering between edge channels strongly modified by the interlayer charge transfer between the front and the back channels.
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