5,064 research outputs found
Diffusion technique stabilizes resistor values
Reduction of the contact resistance stabilizes the values, over a broad temperature range, of resistors used in linear integrated circuits. This reduction is accomplished by p-plus diffusion under the alloyed aluminum contacts
Quantum interference of electrons in a ring: tuning of the geometrical phase
We calculate the oscillations of the DC conductance across a mesoscopic ring,
simultaneously tuned by applied magnetic and electric fields orthogonal to the
ring. The oscillations depend on the Aharonov-Bohm flux and of the spin-orbit
coupling. They result from mixing of the dynamical phase, including the Zeeman
spin splitting, and of geometric phases. By changing the applied fields, the
geometric phase contribution to the conductance oscillations can be tuned from
the adiabatic (Berry) to the nonadiabatic (Ahronov-Anandan) regime. To model a
realistic device, we also include nonzero backscattering at the connection
between ring and contacts, and a random phase for electron wavefunction,
accounting for dephasing due to disorder.Comment: 4 pages, 3 figures, minor change
Investigation of the potentialities of photochemical laser systems. Part I - Survey and analysis Final report, 1 Feb. 1966 - 31 Jan. 1967
Photodissociative laser systems used to convert solar radiation to monochromatic coherent emission - excitation mechanisms, spectroscopy of gases absorbing light, and chemical processe
Quantum ratchets in dissipative chaotic systems
Using the method of quantum trajectories we study a quantum chaotic
dissipative ratchet appearing for particles in a pulsed asymmetric potential in
the presence of a dissipative environment. The system is characterized by
directed transport emerging from a quantum strange attractor. This model
exhibits, in the limit of small effective Planck constant, a transition from
quantum to classical behavior, in agreement with the correspondence principle.
We also discuss parameter values suitable for implementation of the quantum
ratchet effect with cold atoms in optical lattices.Comment: Significant changes: Several text improvements and new results.
Figure 2 modified. Figure 4 adde
The ratchet effect and the transporting islands in the chaotic sea
We study directed transport in a classical deterministic dissipative system.
We consider the generic case of mixed phase space and show that large ratchet
currents can be generated thanks to the presence, in the Hamiltonian limit, of
transporting stability islands embedded in the chaotic sea. Due to the
simultaneous presence of chaos and dissipation the stationary value of the
current is independent of initial conditions, except for initial states with
very small measure.Comment: 5 pages, 6 figure
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