2,618 research outputs found
Numerical Analysis of the Transient Response of Advanced Thermal Protection Systems for Atmospheric Entry
Equations for the transfer of heat through thermal protection shields are derived in finite difference form. These equations are applicable to charring ablators, impregnated ceramics, subliming ablators, heat sinks, and insulating materials and have been programed for solution on a high-speed digital computer. In the program, thermal properties can be functions of temperature. Provision is made for analysis of heat shields subjected to simultaneous convective and radiative heat inputs. Some typical results are presented. Limited comparisons with experimental results are made
Saturation of atomic transitions using sub-wavelength diameter tapered optical fibers in rubidium vapor
We experimentally investigate ultralow-power saturation of the rubidium D2
transitions using a tapered optical fiber (TOF) suspended in a warm Rb vapor. A
direct comparison of power-dependent absorption measurements for the TOF system
with those obtained in a standard free-space vapor cell system highlights the
differences in saturation behavior for the two systems. The effects of
hyperfine pumping in the TOF system are found to be minimized due to the short
atomic transit times through the highly confined evanescent optical mode guided
by the TOF. The TOF system data is well-fit by a relatively simple empirical
absorption model that indicates nanoWatt-level saturation powers.Comment: 6 pages, 6 figure
Cyclical Quantum Memory for Photonic Qubits
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 device. The
memory device utilized a simple free-space storage loop, providing a cyclical
read-out that could be synchronized with the cycle time of a quantum computer.
The coherence of the photonic qubits was maintained during switching operations
by using a high-speed polarizing Sagnac interferometer switch.Comment: 4 pages, 5 figure
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