Factorizability
Erwin Schrödinger told
separability principle (his
Trennungsprinzip) would not apply to
entangled particles.
Schrödinger challenged Einstein's
EPR paper that two systems that had previously interacted can be treated as
separated systems, and that a two-particle wave function
ψ12 can be
factored into a
product of separated wave functions for each system, e.g.,
ψ12 →
ψ1 ψ2.
The particles cannot separate (become disentangled), Schrödinger knew, until another quantum interaction (a
measurement or environmental decoherence)
collapses the wave function ψ
12 and separates them.
Schrödinger wrote about disentanglement...
To disentangle them we must
gather further information by experiment, although we knew as much as anybody
could possibly know about all that happened. Of either system, taken
separately, all previous knowledge may be entirely lost, leaving us but one
privilege: to restrict the experiments to one only of the two systems. After reestablishing
one representative by observation, the other one can be inferred
simultaneously. In what follows the whole of this procedure will be called the
disentanglement...
Attention has recently [viz., EPR] been called to the obvious but very disconcerting fact
that even though we restrict the disentangling measurements to one system, the
representative obtained for the other system is by no means independent of the
particular choice of observations which we select for that purpose and which by
the way are entirely arbitrary. It is rather discomforting that the theory should
allow a system to be steered or piloted into one or the other type of state at the
experimenter's mercy in spite of his having no access to it. This paper does not
aim at a solution of the paradox, it rather adds to it, if possible.
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