1104.0772 (Shih-Yuin Lin)

Instantaneous projective measurements spatially local in a relativistic
quantum field    [PDF]

Shih-Yuin Lin

Suppose the postulate of measurement in quantum mechanics can be extended to
quantum field theory, then a local projective measurement at some moment on an
object locally coupled with a relativistic quantum field will result a
projection or collapse of the wave functional of the combined system defined on
the whole time-slice associated with the very moment of the measurement, if the
relevant degrees of freedom have nonzero correlations. This implies that the
wave functionals in the same Hamiltonian system but defined in different
reference frames would collapse on different time-slices passing through the
same local event where the measurement was done. Are these post-measurement
states consistent with each other? We illustrate that the quantum states of the
Raine-Sciama-Grove detector-field system started with the same initial Gaussian
state defined on the same initial time-slice, then collapsed by the
measurements on the point-like detectors on different time-slices in different
frames, will evolve to the same state of the combined system up to a coordinate
transformation when compared on the same final time-slice. Such consistency is
by virtue of the covariance of the mode functions and the spatial locality of
the measurement events.

View original: http://arxiv.org/abs/1104.0772