1,203 research outputs found
Decoherence and single electron charging in an electronic Mach-Zehnder interferometer
We investigate the temperature and voltage dependence of the quantum
interference in an electronic Mach-Zehnder interferometer using edge channels
in the integer quantum-Hall-regime. The amplitude of the interference fringes
is significantly smaller than expected from theory; nevertheless the functional
dependence of the visibility on temperature and bias voltage agrees very well
with theoretical predictions. Superimposed on the Aharonov-Bohm (AB)
oscillations, a conductance oscillation with six times smaller period is
observed. The latter depends only on gate voltage and not on the AB-phase, and
may be related to single electron charging.Comment: 4 pages, 6 figures, discussion of charging effect change
Counting Statistics and Dephasing Transition in an Electronic Mach-Zehnder Interferometer
It was recently suggested that a novel type of phase transition may occur in
the visibility of electronic Mach-Zehnder Interferometers. Here, we present
experimental evidence for the existence of this transition. The transition is
induced by strongly non-Gaussian noise that originates from the strong coupling
of a quantum point contact to the interferometer. We provide a transparent
physical picture of the effect, by exploiting a close analogy to the
neutrino-oscillations of particle physics. In addition, our experiment
constitutes a probe of the singularity of the elusive full counting statistics
of a quantum point contact.Comment: 7 pages, 4 figures (+Supplement 8 pages, 9 figures
Edge Channel Interference Controlled by Landau Level Filling
We study the visibility of Aharonov-Bohm interference in an electronic
Mach-Zehnder interferometer (MZI) in the integer quantum Hall regime. The
visibility is controlled by the filling factor and is observed only
between and 1.0, with an unexpected maximum near .
Three energy scales extracted from the temperature and voltage dependences of
the visibility change in a very similar way with the filling factor, indicating
that the different aspects of the interference depend sensitively on the local
structure of the compressible and incompressible strips forming the quantum
Hall edge channels.Comment: 5 pages, 5 figures, final version accepted for publication in Phys.
Rev.
Bistability in superconducting rings containing an inhomogeneous Josephson junction
We investigate the magnetic response of a superconducting Nb ring containing
a ferromagnetic PdNi Josephson junction and a tunnel junction in parallel. A
doubling of the switching frequency is observed within certain intervals of the
external magnetic field. Assuming sinusoidal current-phase relations of both
junctions our model of a dc-SQUID embedded within a superconducting ring
explains this feature by a sequence of current reversals in the ferromagnetic
section of the junction in these field intervals. The switching anomalies are
induced by the coupling between the magnetic fluxes in the two superconducting
loops.Comment: 5 pages, 4 figure
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