2 research outputs found
Quantum pump driven fermionic Mach-Zehnder interferometer
We have investigated the characteristics of the currents in a pump-driven
fermionic Mach-Zehnder interferometer. The system is implemented in a conductor
in the quantum Hall regime, with the two interferometer arms enclosing an
Aharonov-Bohm flux . Two quantum point contacts with transparency
modulated periodically in time drive the current and act as beam-splitters. The
current has a flux dependent part as well as a flux independent
part . Both current parts show oscillations as a function of frequency
on the two scales determined by the lengths of the interferometer arms. In the
non-adiabatic, high frequency regime oscillates with a constant
amplitude while the amplitude of the oscillations of increases
linearly with frequency. The flux independent part is insensitive to
temperature while the flux dependent part is exponentially
suppressed with increasing temperature. We also find that for low amplitude,
adiabatic pumping rectification effects are absent for semitransparent
beam-splitters. Inelastic dephasing is introduced by coupling one of the
interferometer arms to a voltage probe. For a long charge relaxation time of
the voltage probe, giving a constant probe potential, and the part
of flowing in the arm connected to the probe are suppressed with
increased coupling to the probe. For a short relaxation time, with the
potential of the probe adjusting instantaneously to give zero time dependent
current at the probe, only is suppressed by the coupling to the
probe.Comment: 10 pages, 4 figure
Current-voltage correlations in interferometers
We investigate correlations of current at contacts and voltage fluctuations
at voltage probes coupled to interferometers. The results are compared with
correlations of current and occupation number fluctuations at dephasing probes.
We use a quantum Langevin approach for the average quantities and their
fluctuations. For higher order correlations we develop a stochastic path
integral approach and find the generating functions of voltage or occupation
number fluctuations. We also derive a generating function for the joint
distribution of voltage or occupation number at the probe and current
fluctuations at a terminal of a conductor. For energy independent scattering we
found earlier that the generating function of current cumulants in
interferometers with a one-channel dephasing or voltage probe are identical.
Nevertheless, the distribution function for voltage and the distribution
function for occupation number fluctuations differ, the latter being broader
than that of former in all examples considered here.Comment: 23 pages, 10 figures, minor changes, additional appendix, added
reference