581 research outputs found
Quantum transport in chains with noisy off-diagonal couplings
We present a model for conductivity and energy diffusion in a linear chain
described by a quadratic Hamiltonian with Gaussian noise. We show that when the
correlation matrix is diagonal, the noise-averaged Liouville-von Neumann
equation governing the time-evolution of the system reduces to the Lindblad
equation with Hermitian Lindblad operators. We show that the noise-averaged
density matrix for the system expectation values of the energy density and the
number density satisfy discrete versions of the heat and diffusion equations.
Transport coefficients are given in terms of model Hamiltonian parameters. We
discuss conditions on the Hamiltonian under which the noise-averaged
expectation value of the total energy remains constant. For chains placed
between two heat reservoirs, the gradient of the energy density along the chain
is linear.Comment: 6 pages, to appear in J. Chem. Phy
ORGANIZATIONAL-ECONOMIC ASPECTS OF SHIPPING COMPANIES BUSINESS DEVELOPMENT ON RUSSIAN SEA CRUISE MARKET
In the article the tendencies of development of the Russian sea cruises market are considered, the state of the organization Russian service onboard foreign cruise companies is analyzed, the major cruise companies represented in Russia are highlighted and SWOT-analysis of Russian tour operators is done
Microwave-Induced Dephasing in One-Dimensional Metal Wires
We report on the effect of monochromatic microwave (MW) radiation on the weak
localization corrections to the conductivity of quasi-one-dimensional (1D)
silver wires. Due to the improved electron cooling in the wires, the MW-induced
dephasing was observed without a concomitant overheating of electrons over wide
ranges of the MW power and frequency . The observed dependences of
the conductivity and MW-induced dephasing rate on and are in
agreement with the theory by Altshuler, Aronov, and Khmelnitsky \cite{Alt81}.
Our results suggest that in the low-temperature experiments with 1D wires,
saturation of the temperature dependence of the dephasing time can be caused by
an MW electromagnetic noise with a sub-pW power.Comment: 4 pages with 4 figures, paper revised, accepted by Phys Rev Let
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