appendix c
c o n t r o v e r s y c o n c e r n i n g t h e
r e l a t i o n s h i p b e t w e e n b o h r s p r i n c i p l
o f c o m p l e m e n t a r i t y a n d h e i s e n b e r g s
u n c e r t a i n t y p r i n c i p l e
The nature of the relationship between Heisenberg’s uncertainty pri
and Bohr’s complementarity, sparked by the work of Scully et al. (1991
been a matter of some controversy. The claim of Scully et al. that
experiment o√ers definitive evidence of the loss of interference witho
disturbance caused by the detector has been contested by Storey et al. (1
Storey et al. argue that complementarity is always enforced by the uncer
relations, that is, by an uncontrollable momentum transfer (disturba
thereby arguing that it is the more fundamental principle than comple
tarity, in contradiction to Scully et al. and the point of view that I espouse
Wiseman and Harrison (1995) argue that the kind of random mome
kick that Storey et al. enlist to explain the destruction of the interfe
pattern is in general not the same as the classical notion but rather a st
nonlocal beast involving the ‘‘more subtle idea of momentum-kick a
tudes’’ (within an entangled state!) (for more details, see Wiseman
1997). Furthermore, Wiseman and Harrison argue that while the Ein
recoiling-slit gedanken experiment may be—but need not be—understo
terms of uncontrolled classical momentum kicks, this is not the case f
experiment suggested by Scully et al. (and confirmed by Eichmann
[1993]). However, as Wiseman and Harrison point out, such a cla
analysis of the recoiling-slit experiment is based on a naive-realist inter
tion of the uncertainty principle, which, needless to say, Bohr defin
disclaims. (There may be a lot of controversy concerning Bohr’s philos
physics, but no scholar will argue that Bohr is a naive realist.)
See also the results of Dürr et al. (1998b), who specifically examin
mechanical e√ects of which-path detection experimentally and show
‘‘the back action onto the atomic momentum [i.e., momentum kick o
turbance] implied by Heisenberg’s position-momentum uncertainty re
cannot explain the loss of interference’’ (33). Rather, they argue th
‘‘correlations between the which-way detector and the atomic motion
the entanglement of ‘‘object’’ and ‘‘apparatus’’] destroy the interfe
fringes’’ (33). They also make the point that ‘‘correlations between the
fering particle and the detector system are produced in any whic
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