301 research outputs found

    Ultrafast slow-light: Raman-induced delay of THz-bandwidth pulses

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    We propose and experimentally demonstrate a scheme to generate optically-controlled delays based on off-resonant Raman absorption. Dispersion in a transparency window between two neighboring, optically-activated Raman absorption lines is used to reduce the group velocity of broadband 765 nm pulses. We implement this approach in a potassium titanyl phosphate (KTP) waveguide at room temperature, and demonstrate Raman-induced delays of up to 140 fs for a 650-fs duration, 1.8-THz bandwidth, signal pulse; the available delay-bandwidth product is ≈1\approx1. Our approach is applicable to single photon signals, offers wavelength tunability, and is a step toward processing ultrafast photons.Comment: 5+4 pages, 4+2 figure

    Time-bin to Polarization Conversion of Ultrafast Photonic Qubits

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    The encoding of quantum information in photonic time-bin qubits is apt for long distance quantum communication schemes. In practice, due to technical constraints such as detector response time, or the speed with which co-polarized time-bins can be switched, other encodings, e.g. polarization, are often preferred for operations like state detection. Here, we present the conversion of qubits between polarization and time-bin encodings using a method that is based on an ultrafast optical Kerr shutter and attain efficiencies of 97% and an average fidelity of 0.827+/-0.003 with shutter speeds near 1 ps. Our demonstration delineates an essential requirement for the development of hybrid and high-rate optical quantum networks

    Observation of high-order quantum resonances in the kicked rotor

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    Quantum resonances in the kicked rotor are characterized by a dramatically increased energy absorption rate, in stark contrast to the momentum localization generally observed. These resonances occur when the scaled Planck's constant hbar=(r/s)*4pi, for any integers r and s. However only the hbar=r*2pi resonances are easily observable. We have observed high-order quantum resonances (s>2) utilizing a sample of low temperature, non-condensed atoms and a pulsed optical standing wave. Resonances are observed for hbar=(r/16)*4pi r=2-6. Quantum numerical simulations suggest that our observation of high-order resonances indicates a larger coherence length than expected from an initially thermal atomic sample

    IMPACT EVALUATION OF AN ENERGY SAVINGS PLAN PROJECT AT THE LINDE DIVISION OF UNION CARBIDE CORPORATION

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    This impact evaluation of an energy conservation measure (ECM) that was recently installed at the Linde Division of Union Carbide Corporation (Linde) was conducted far the Bonneville Power Administration (Bonneville) as part of an evaluation of its Energy Savings Plan (ESP) Program. The Program makes acquisition payments to firms that install energy conservation measures in their industrial processes. The objective of this impact evaluation was to assess how much electrical energy is being saved at Linde as a result of the ESP and to determine how much the savings cost Bonneville and the region. The impact of the ECM was evaluated with a combination of engineering analysis, financial analysis, site visit and interviews, and submittal reviews (Linde's Completion Report and Abstract). The ECM itself consists of replacing the plant's nitrogen feed compressor with a larger unit, which allows the plant to meet its argon demand using less compressed air and which results in net energy savings. Energy savings resulting from this ECM were 4,376,500 kWh/yr for the first two years after installation, but, because of a change in Linde's market position, long-term savings are expected to be lower at 2,549,200 kWh/yr. Linde considers energy consumption and savings on a per ton basis to be proprietary, so they are not reported here. The ECM cost 361,4.96toinstall,andLindereceivedpaymentof361,4.96 to install, and Linde received payment of 161,426 from Bonneville for the acquisition of energy savings. This ECM would not have been implemented without the acquisition payment from Bonneville. The levelized cost of these energy savings to Bonneville will be 4.5 mills/kWh over the ECM's expected 15-year life, and the levelized cost to th.e region will be 5.9 mills/kWh

    Potential for ultrafast dynamic chemical imaging with few-cycle infrared lasers

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    We studied the photoelectron spectra generated by an intense few-cycle infrared laser pulse. By focusing on the angular distributions of the back rescattered high energy photoelectrons, we show that accurate differential elastic scattering cross sections of the target ion by free electrons can be extracted. Since the incident direction and the energy of the free electrons can be easily changed by manipulating the laser's polarization, intensity, and wavelength, these extracted elastic scattering cross sections, in combination with more advanced inversion algorithms, may be used to reconstruct the effective single-scattering potential of the molecule, thus opening up the possibility of using few-cycle infrared lasers as powerful table-top tools for imaging chemical and biological transformations, with the desired unprecedented temporal and spatial resolutions.Comment: 16 pages, 6 figure
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