We investigate a mechanism for extracting heat from metallic conductors based
on the energy-selective transmission of electrons through a spatially
asymmetric resonant structure subject to ac driving. This quantum refrigerator
can operate at zero net electronic current as it replaces hot by cold electrons
through two energetically symmetric inelastic channels. We present numerical
results for a specific heterostructure and discuss general trends. We also
explore the conditions under which the cooling rate may approach the ultimate
limit given by the quantum of cooling power.Comment: 4 pages, 3 figures; published version, typos correcte
We present a scattering theory of the electromotive force and internal
resistance of an electron pump. The characterization of the device performance
in terms of only two parameters requires the assumption of incoherent multiple
scattering within the circuit and complete thermalization among electrons
moving in a given direction. The electromotive force is shown to be of the
order of the driving frequency in natural units. In an open setup, the
electromotive force adds to the voltage difference between reservoirs to drive
the current, both facing a contact resistance which is absent in the case of a
closed circuit of uniform width
We explore the possibility of inducing in heterostructures driven by an ac
gate voltage the coherent current suppression recently found for nanoscale
conductors in oscillating fields. The destruction of current is fairly
independent of the transport voltage, but can be controlled by the driving
amplitude and frequency. Within a tight-binding approximation, we obtain
analytical results for the average current in the presence of driving. These
results are compared against an exact numerical treatment based on a
transfer-matrix approach.Comment: 18 pages, 4 figures, elsart style, corrected proo
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