Ad. Parks et al., OBSERVATION AND MEASUREMENT OF AN OPTICAL AHARONOV-ALBERT-VAIDMAN EFFECT, Proceedings - Royal Society. Mathematical, physical and engineering sciences, 454(1979), 1998, pp. 2997-3008
Citations number
15
Categorie Soggetti
Multidisciplinary Sciences
Journal title
Proceedings - Royal Society. Mathematical, physical and engineering sciences
The notion of the weak value of a quantum mechanical observable has re
cently been introduced by Aharonov ct al., hereafter referred to as AA
V. Their analysis led to the controversial result that the weak values
for an observable can lie well outside its associated eigenvalue spec
trum. We have performed an experiment similar to one proposed by Knigh
t ct al. and demonstrated that weak values can be observed and that th
ey exhibit the properties described by AAV within the regime of validi
ty defined by Duck et al. It is shown that these properties are produc
ed by interference phenomena that result from the loss of 'welcher Weg
' information. We have also identified an intrinsic 'weak energy' whic
h appears in the equation of motion for the weak value of an observabl
e and have shown that it can be non-vanishing only for systems which a
re both preselected and postselected. It is noted that such a 'weak sp
in-rotation coupling energy' can be associated with our experiment and
that it is manifested in our experimental data. We suggest that prese
lection and postselection measurement techniques could be useful for t
he creation and study of physical phenomena that might be otherwise un
observable.