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 is taken the form
V(x,t)=
V
0
θ(x)θ(a−x)cos(ωt)
, with
a
the range of the potential and
x
the transmission direction. As the chemical potential
μ
is increasing, the dc conductance
G
is found to exhibit dip, or peak, structures when
μ
is at
nℏω
above the threshold energy of a subband. These structures in
G
are found in both the small
a
(
a≪
λ
F
) and the large
a
(
a≫
λ
F
) regime. The dips, which are associated with the formation of quasi-bound states, are narrower for smaller
a
, and for smaller
V
0
. The locations of these dips are essentially fixed, with small shifts only in the case of large
V
0
. Our results can be reduced to the limiting case of a delta-profile oscillating potential when both
a
and
V
0
a
are small. The assumed form of the time-modulated potential is expected to be realized in a gate-induced potential configuration.