Dear Professor ,
I am sending you a
paper entitled “Haunted Quantum Entanglement” that
was presented
at the Joint Spring Meeting of the Ohio Sections of the
APS and
AAPT (http://meetings.aps.org/link/BAPS.2009.OSS.P1.27)
. I
think you might be interested in it. Another paper of
mine you might
be interested in is at: http://cdsweb.cern.ch/record/1019984?ln=en
.
Below you will find a general description of how I arrived
at the idea
of haunted quantum
entanglement.
Sincerely,
Dr. Douglas Snyder
Los
Angeles,
CA
-----------------------------------------------------------------------------------------------
First,
Mermin’s articles in AJP and Physics Today on EPR from years
ago
made a particular impression upon me regarding the need
to
associate measurements on each of two entangled particles
after
measurements on each of the particles in order to
decipher
information.
After reading Mermin’s articles, I
read Greenberger and YaSin’s
haunted measurement article in
Foundations of Physics. In their
article, they
demonstrated that one could undo a which-way
measurement.
Greenberger and YaSin did this with a neutron
traveling
through an interferometer for which there was a movable
mirror system
along one arm. When the neutron struck the
first mirror of the
movable mirror system, there was a which-way
measurement. When the
neutron finished interacting with the
movable mirror system, the
neutron and mirror system were
returned to their original states,
i.e., the states they had
before the neutron struck the first mirror
of the movable mirror
system. The neutron exhibited interference when
it exited
the interferometer. Greenberger and YaSin’s result
depended
essentially on the isolation of the interactions of the
neutron and
movable mirror system from the environment.
I
next read Scully’s article in Nature on the quantum eraser where
he
and his colleagues showed that one could get interference in
the forms
of fringes and anti-fringes after having conducted a
which-way
measurement. In line with Mermin’s articles,
Scully’s fringes and
anti-fringes relied on associating
measurements on each of two
entangled particles in order to
decipher information.
I thought perhaps one could adapt
Greenberger and YaSin’s haunted
measurement which concerned a
single particle to entangled particles.
One might then have a
haunted entanglement. Scully had an atom pass
through a
micromaser cavity system and emit a photon in one of the
two
cavities. Scully emphasized that the atom’s emission of
the photon
did not affect the motion of the atom in any
significant way. The
atom passes through a double slit and
begins its travel to a detection
screen. Between the double
slit and the detection screen, shutters
open for each micromaser
cavity and a photodetector is exposed between
the two micromaser
cavities. The photon may or may not be detected.
One
possibility is associated with the fringe pattern of the atom
at
the detection screen, and the other possibility is associated
with the
anti-fringe pattern of the atom at the detection screen.
According to
Scully, which-way information for the atom was
firmly established with
the atom’s passage through the double
slit. When the atom passes
through the double slit, the
emitted photon is in one or the other of
the micromaser cavities.
The entanglement of the atom and photon
indicates through
which slit the atom passed since there is a one to
one
correspondence between a micromaser cavity and slit. The sum
of
the fringe and anti-fringe patterns is an overall distribution
pattern
characteristic of which-way information that is
established from the
atom’s passage through the double slit while
the photon is in only one
of the micromaser cavities.
I
adapted Scully’s method in the following way. I thought
that
instead of two shutters and a photodetector, use just a
single shutter
between the micromaser cavities. If the
shutter opens, one loses
which-way information for the photon.
If the shutter remains closed
until after the atom passes
through the double slit screen, the atom
exhibits a which-way
distribution at the detection screen (no
interference) in a
series of runs of the setup in this mode. If the
shutter
opens before the atom reaches the double slit screen, the
atom
exhibits interference at the detection screen, the same form
of
distribution the atom would exhibit if there were no
micromaser cavity
system for the atom to pass through on its way
to the double slit
screen. (We are not dealing here with
fringes and anti-fringes.)
With the opening of the shutter in the
manner noted, the entanglement
is essentially lost and can be
considered to have been a haunted
entanglement. I have
thought this method gets around the need for
associating
measurements on each of two entangled particles in order
to
derive information. One controls whether a developing
entanglement
is allowed to be fully established or instead
effectively eliminated
through what happens with the shutter
between the micromaser cavities.
After adapting Scully’s
experiment to show haunted quantum
entanglement, I developed an
implementation using photons alone.
I have attached records
from the APS server of the poster
presentations made at annual
meetings beginning in 2005.
I should note that when I use the
term "hidden" in my papers, I
generally mean
"isolated."
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hqe_aps_ohio.pdf
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new_aps_quantum_papers.doc
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