From: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: Progress Report FTL QM Communication
Organization: Whole Earth 'Lectronic Link
Date: Tue, 1 Sep 1992 01:53:26 GMT


Progress Report on FTL Communication
by Jack Sarfatti

#1 In the LBL Internet article on tachyons, it is asserted that tachyon
waves cannot be used for FTL communication. This is debatable since the
argument appears to ignore dispersion in a wavepacket in E^2 = p^2 - m^2
(c=1) in which the group (particle) speed dE/dp > c while the phase
(wavefront) speed E/p < c. The error in the LBL article is the confusion
the subluminal wavefront speed of the tachyon with the superluminal
particle speed which would be the signal speed. The FTL particle speed
of tachyonic signal propagation is due to interference between the
different frequencies in the wavepacket which was ignored in the LBL
article.

#2 Even if I am wrong in #1, the LBL article's point does not apply to
FTL and BIT (backward-in-time) "nonmetrical" spin phase communication on
the nonlocal quantum connection which does not require direct signal
propagation along the family of worldlines (geodesic and non-geodesic)
connecting the transmitting event T with the receiving event R. The
signal propagation between T and R is the "Feynman zig zag"(Costa de
Beauregard) via the event S that emitted the photon pair in which the
transmitter photon is detected at T and the receiver photon is detected
at R.

#3 My initial design (I) had a transmitter consisting of a calcite
crystal cut and positioned such that the incident photon path splits
into E and O separated paths with perpendicular linear polarizations
determined by the actual orientation of the calcite in space when the
photon locally interacts with it at event T.

#4 The E path passes a variable phase shift plate, whose setting is phi,
on which the message is encoded for a stream of successive paired
photons from the worldline of S.

#5 The phase plate E output is reflected by a mirror into input port E
of a beam recombiner.

#6 The O path passes a half-wave plate oriented at 45 degrees to the
plane of O polarization. The half-wave plate rotates the O polarization
by 90 degrees to line up with the E polarization.

#7 Therefore, the half-wave plate is a "spin quantum eraser" which
destroys the distinguishability of the two alternative Feynman histories
for the transmitter photon in spin fiber space beyond space-time.

#8 The E output from the half-wave plate is fed into the second O input
port of the beam recombiner.

#9 Therefore, the two output ports of the beam recombiner each contain
contributions from the two input ports. However, in the case of pair-
correlated light the E and O inputs to the recombiner remain
distinguishable because of the nonlocal quantum connection to non-
overlapping (i.e., orthogonal) polarization states of the twin receiver
photon created with the transmitter photon at event S.

#10 This distant quantum connection destroys the normally expected local
first order coherence (fringe visibility) with changing phase plate
setting.

#11 The receiver calcite at event R is misaligned by angle x relative to
the orientation of the transmitter calcite at T. The receiver calcite
splits the incident receiver photon path into e and o paths each fed
into their own receiver counters.

#12 The phase shift between reflected and transmitted outputs (for
single input) of the transmitter recombiner (aka "beam splitter") is b.

#13  In design I, the two recombiner outputs are fed to different photon
counters. In that case the standard quantum mechanical prediction is
that the difference of the count rates for the two receiver detectors is
proportional to

R(t) = p[e] - p[o] = sin[2x] cos[phi(t)] cos[b]  (for Design I)      (1)

#14 Aephraim Steinberg and referee A from Phys. Rev. Letters and others
both remarked that local unitarity of the transmitter photon state
transformation at the beam splitter require b = pi/2 so that cos[b] = 0
because

r*t + rt* = |r||t|cosb = 0                                      (2)

Therefore, R(t) = 0 and FTL communication is not possible by this
device, they conclude.

#15 Apart from this point the Phys. Rev. Letter referee A does not
dispute my basic set up and method in deriving the quantum equations for
a general transformation at the beam splitter.

#16 After thinking about #14 I discovered that if we recombine the beam
splitter outputs into a single specially designed clamped counter (i.e.,
Design II), rather than two, then quantum mechanics predicts that the
cos[b] factor in equation (1) of #13 is no longer there because a common
factor of (r+t) is in every term of the pair amplitude rather than
separate terms having either r or t (r is complex reflection transfer
function and t is transmission function). Indeed, now unitarity at the
beam splitter helps us rather than kills us, because it implies:

(r*+t*)(r+t) = r*r + t*t + r*t + rt* = 1                        (3)

and standard quantum mechanics gives

R(t) = (r*+t*)(r+t)sin[2x] cos[phi(t)] = sin[2x] cos[phi(t)]    (4)

#17 The conventional wisdom that unitarity prevents faster-than-light
(FTL) and backwards-in-time (BIT) communication is thus refuted by this
counter-example.

#18 We get BIT in a "delayed choice" (Wheeler) geometry in which T is in
the frame-invariant timelike future of R. The nonlocal quantum forces of
Bohm's "quantum potential" prevent causal paradoxes and provide "La
Forza del Destino". Cal Tech's Kip Thorne et-al have given equivalent
arguments for traversable wormhole time machines permitting closed
timelike worldlines in general relativity.

#19 We might even get Design I to work by doing a fluctuation analysis.
For example, if the power spectrum of b fluctuations at the transmitter
beam splitter is not white noise (i.e., f^0) or even pink noise
(i.e.,f^-1) but is at least brown noise (f^-2) and better yet black
noise (f^-(2+epsilon)) then the memory allows windows of opportunity to
surf on the long time b fluctuations and send fast messages inside the b
fluctuations. The point is that doing something to enhance the b
fluctuation correlations in a short length of T worldline while quieting
the phi and x fluctuations would permit FTL and BIT messages. However,
Design II means we do not have to go to all this trouble. The nature of
quantum noise, especially quantum spin noise is of intrinsic interest
for the coming advanced ultra-fast ultra-intelligent nanotech quantum
computers.




Xref: sparky sci.physics:13675 sci.math:10621 comp.sys.sun.wanted:1361