Which phase is measured in the Aharonov-Bohm interferometer?
Amnon Aharony
Tel Aviv University
When a wave splits through two slits, one obtains an
interference pattern which depends on the phase difference
between the two paths. Recently, experiments studied
mesoscopic solid state interferometers, based on two
narrow paths. A magnetic flux enclosed between the
paths generates a Aharonov-Bohm phase difference,
yielding a current which is periodic in the flux. This
dependence on the flux has been used to measure a phase
shift, interpreted as the intrinsic phase of the transmission
via a quantum dot located on one of the paths. In the
present talk I show that the measured phase shift is usually
not representing this intrinsic phase; except for very
specific conditions (not yet discussed in the textbooks
which discuss the Aharonov-Bohm interferometer),
the measured phase shift is due to losses of current out of
the paths. I then discuss possible arrangements which may
still yield the desired intrinsic phase.