Quantum Decoherence - heavy matterwave collision-emission
- From: "zekise" <zekise@xxxxxxxxx>
- Date: Wed, 15 Feb 2006 20:19:13 +0000 (UTC)
Hi everybody! As a non-formal layperson (with a science background)
trying to muddle my way to quantum informatics, I have navigated
through a somewhat respectable share of complementarity, entanglement,
decoherence, Scully, Zeilinger, Zurek and Schlosshauer. Several
questions regarding the issue of decoherence of matterwaves have come
up which I have posted on another forum for a while now, but which have
had no takers. I would greatly appreciate any help on any of these
questions - TIA muchly:
Recent interference experiments with massive molecules, such as
fluoro-fullerene C60F48 consisting of atomic mass 1632, see heavy
matterwave experiment http://physicsweb.org/articles/world/18/3/5/1,
show that the interference pattern (IP) will disappear if the FF
molecule emits a thermal photon, or collides with a gas particle, where
the mass of the gas particle is immaterial.
The emission or collision produces an entangled pair with the FF
molecule. Therefore, as shown in entanglement experiments (Scully,
Walborn), the IP fringe disappears and gets obscured by the other
entangled member, and can only be revealed if we capture the entangled
particle, and do a coincidence selection. Original fringe cannot be
revived.
Question 1) Is there such a thing as a "quantum coherent state" for
a single particle? Now in the heavy molecule experiment, Zeilinger et
al used a Talbot-Lau grating to collimate the FF beam. This would be a
necessary step to observe interference. However, if the experiment can
be practically done on a single molecule, would this be necessary? So
is it correct to say that when the FF solid sublimates, and a single
molecule flies at the interferometer, that it is already in a coherent
state? That is, if the molecule is NOT entangled in any manner and
therefore IS isolated (?), it will be in a coherent state?
Question 2) Assume a single FF molecule is coherent and flies through
the interferometer. Assume that we somehow are able to figure out
(calculate) the sublimation ejection trajectory (without perturbation
of the molecule) before the slits, and therefore calculate which slit
the molecule will pass through - would this not put it in a mixed state
and destroy the IP? Would this, if possible, be an example of
non-entangled decoherence? Is there such a thing?
Q3) Now the FF molecule consists of 2,448 particles bound together by
electric and nuclear forces. I assume this entangles the components of
the molecule with each other (?), as they are continuously interacting
with one another. Why is it that this entanglement does not decohere
the molecule, in the manner that an emitted thermal photon does - and
result in IP loss?
Q4) If the FF emits an ionization electron instead of a thermal photon,
I understand this electron can be entangled with the molecule. Is this
always the case, or only if it is emitted in a certain manner? Now
assuming the electron before ionization was entangled with the
molecule, and remains entangled after emission, then what is now
different that results in the IP disappearing due to this emission?
Q5) Do all interactions result in a degree of entanglement? If this is
the case a particle must always be in a state of perpetual entanglement
with a huge number of other particles as force fields can travel quite
a distance. Is it fair to say most particles are entangled with a huge
number of other particles to some degree? Is it possible to have
incomplete (partial) entanglement?
Q6) Assume one photon of a momentum entangled pair of photons is
absorbed by an isolated atom. Under what condition is the entanglement
broken, or that it survives and gets transferred to the atom?
Regards to all
.
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