PHOTOCONDUCTIVITY OF A QUANTUM BALLISTIC CONTACT

The electron transport through a microscopic constriction in a two-dim ensional quantum channel in an alternating transverse electromagnetic field is considered. A general expression is derived for the photocond uctivity as a function of elements of a multichannel scattering S-matr ix. This expression generalizes the Landauer formula for the conductiv ity of a 2D ballistic point contact (BPC) to the case of inelastic pro cesses of interaction of ballistic electrons with alternating electrom agnetic field. The relation between the symmetry of the S-matrix of el ectrons and the transport properties of the BPC in a nonstationary fie ld is considered, The photoconductivity of a BPC with an adiabatic geo metry is obtained in the semiclassical approximation. (C) 1997 America n Institute of Physics.