The method of faster than light (FTL) communication suggested below,
assuming it fails, must fail due to all photons, both those absorbed and
those passed, becoming non-entangled upon passing through the first filter.
This is counter-intuitive in that one would expect the photons
successfully passing though the filter H1, being non-absorbed and further
being not committed to a polarization direction, to remain entangled. It
is, for example, possible (probability about 12.5 percent) for a single
photon to pass through H1, D1 and V1. This means that such a photon in
effect got to "roll the dice" regarding its polarization direction each
time it went through a filter. Its polarization direction is not fixed
until it hits filter H2. It passed, like a chameleon that changes color,
through *both* filters H1 and V1 without absorption, so had no commitment
to any specific polarization direction until finally absorbed. It
therefore seems counter-intuitive that its conjugate is dis-entagled
immediately when the local photon passes through the first filter H1, even
though both photons of the pair are still in free-flight and still free to
act like chameleons, rolling the dice when confronted with each subsequent
polarizing filter.
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Simple FTL Communication Method (Draft #2)
A method of communication is proposed here that uses the instantaneous
teleportation of quantum state of entangled photons to communicate a signal
faster than light speed. The method depends on the fact that when the
polarization state of one member of an entangled pair of photons is
determined, i.e. measured, the conjugate photon will then be measured in
the conjugate state.
The method consists of the following steps:
1. Use of an entangled photon generator which creates two channels of
unpolarized yet entangled photons: the local channel and the communication
channel. The photons in the communication channel are conjugates of their
entangled counterparts in the local channel. The polarization direction of
conjugate pairs, once eventually determined, is mutually orthogonal.
2. A delay is provided in the local channel by use of a fiber delay loop or
other delaying mechanism such that a communication signal is only imposed
upon the local channel photons at about the time of but before receipt of
the paired communication channel photons at the destination. The local
channel is assumed to be located entirely at the transmitting site.
Alternatively the entangled photon generator can be located at the half-way
point between sender and receiver, Alice and Bob, and beam one channel to
each.
3. Photons in the local channel, after sufficient delay, are routed through
one of two paths, the long path or the short path. This switching can be
achieved using a fast electromechanical mirror or other means. In the long
path the photons are routed through a horizontal filter H1, then a diagonal
filter D1, then a vertical filter V1 and then through another horizontal
filter H2, In the short path the local photons are directed through a
horizontal filter H3 and then a vertical filter V3.
4. Photons in the communication channel are passed through a vertical
polarized filter V4 at Bob's location and the remaining signal detected.
(Alternatively a horizontal filter could be used by Bob or Bob can separate
the communication channel beam into horizontal and vertically polarized
components using a calcite crystal and measure the comparative brightness
of the two. Alice can similarly use calcite or other beam splitting means
instead of filters.)
5. The timing of switching between the long and short paths of the local
channel is manipulated by Alice so as to send meaningful messages to Bob.
In the short path every local path photon is in effect measured by Alice as
being either horizontally or vertically polarized, and with a 0.5
probability of being either. In fact, as an alternative to using
polarizing filters, Alice could actually separate the local beam into two
halves and actually measure individual photon polarizations or even just
relative beam brightness. Half the photons are absorbed by H3 and thus
measured as vertical, and the remaining half are absorbed by V3 and thus
measured as horizontal. Bob should detect 50/50 polarization on his end
when Alice is directing the local photons through the short path.
When the long path is used it is well known that the beam emerging from
filter V1 is not null and in fact has about an eighth of the brightness of
the original beam. The beam emerging from V1, being vertically polarized,
is then fully absorbed by the subsequent H2 filter. Since 50 percent of
the local photons are absorbed by H1 and thus detected as vertical, and
12.5 percent of the photons are finally absorbed by H2 and thus detected as
vertically polarized, most of the local beam, at least 62.5 percent, is
detected as vertically polarized. Bob should thus at a slightly later time
detect most of the conjugates, at least 62.5 percent, as horizontally
polarized. Alice need do no actual photon detection to achieve the
communication. Bob need do no individual photon detection to achieve the
communication. The communication is achieved by simply measuring beam
brightness changes following polarization based separation at Bob's
location. This has many advantages in both signal reliability and device
cost. This assumes a beam of sufficient intensity can be obtained so that
a 25 percent difference in intensity can be rapidly measured with
sufficient confidence to be useful for communications.
An experiment requiring the simplest possible message would involve sending
a bit (actually only a change of channel state) via a one-way FTL
communication channel and returning it via a second one-way return FTL
communication channel, and repeating this process to establish an
oscillation. To demonstrate FTL communication it is then necessary to
transmit over a sufficient distance D that the oscillation frequency, f, is
faster than the oscillation frequency F = c/D that can be achieved by
light. A 10 km communication link (each way) need only cycle faster than
about 15 kHz to break the light speed barrier.
Regards,
Horace Heffner
