Quantum transport in the presence of a finite-range time-modulated potential

Abstract

Quantum transport in a narrow constriction and in the presence of a finite-range time-modulated potential is studied. The potential takes the form V(x,t) = V-0 theta(x)theta(a-x)cos(omega t), with a the range of the potential and x the transmission direction. Intrasubband transitions for the electrons and for arbitrary omega are made possible by the finiteness in the potential range. Our results show that, as the chemical potential mu increases, the dc conductance G exhibits dip structures when mu is at nn omega above the threshold energy of a subband. These structures in G are found in both the small a (a similar to lambda) and the large a (a much greater than lambda) regime. These dips are associated with the formation of quasi-bound-states. Our results can be reduced to the limiting case of a delta-profile oscillating potential when both a much less than lambda and V(0)a much less than 1 are satisfied. The assumed form of the time-modulated potential is expected to be realized in a gate-induced potential configuration.