Coherent resonant transport through a mesoscopic system with quantum ac microwave field |
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Authors: | H-K Zhao J Wang |
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Institution: | (1) Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China, CN;(2) Department of Physics, Beijing Institute of Technology, Beijing 100081, China, CN |
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Abstract: | The time-dependent transport through an ultrasmall quantum dot coupling to two electron reservoirs is investigated. The quantum
dot is perturbed by a quantum microwave field (QMF) through gate. The tunneling current formulae are obtained by taking expectation
values over coherent state (CS), and SU(1,1) CS. We derive the transport formulae at low temperature by employing the nonequilibrium
Green function technique. The currents exhibit coherent behaviors which are strongly associated with the applied QMF. The
time-dependent currents appear compound effects of resonant tunneling and time-oscillating evolution. The time-averaged current
and differential conductance are calculated, which manifest photon-assisted behaviors. Numerical calculations reveal the similar
properties as those in classical microwave field (CMF) perturbed system for the situations concerning CS and squeezed vacuum
SU(1,1) CS. But for other squeezed SU(1,1) CS, the tunneling behavior is quite different from the system perturbed by a single
CMF through gate. Due to the quantum signal perturbation, the measurable quantities fluctuate fiercely.
Received 28 May 1998 |
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Keywords: | PACS 73 40 -c Electronic transport in interface structures - 73 20 Dx Electron states in low-dimensional structures (superlattices quantum well structures and multilayers) - 72 10 Bg General formulation of transport theory |
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