From: Jim Choate <ravage@ssz.com>
Date: Sat, 15 Jun 1996 15:38:13 +0800
To: cypherpunks@toad.com
Subject: update.275 (fwd)
Message-ID: <199606150224.VAA07948@einstein.ssz.com>
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Forwarded message:
>From physnews@aip.org Fri Jun 14 18:39:08 1996
Date: Fri, 14 Jun 96 16:45:16 EDT
From: physnews@aip.org (AIP listserver)
Message-Id: <9606142045.AA11832@aip.org>
To: physnews-mailing@aip.org
Subject: update.275


PHYSICS NEWS UPDATE                         
The American Institute of Physics Bulletin of Physics News
Number 275  June 14, 1996    by Phillip F. Schewe and Ben Stein

THE FIRST QUANTUM COMMUNICATION USES "TRITS"
INSTEAD OF BITS.  For the first time, physicists have exploited
the laws of quantum mechanics to send data, and with their
technique have conveyed information more efficiently than with
traditional means.     In contrast to a traditional computer, in which
messages consist of tiny electric pulses encoded in binary form
(i.e., streams of 0s and 1s), researchers at the University of
Innsbruck in Austria send messages consisting of single photons
which can be coded as 0s, 1s, and 2s, setting up a base three system
called "trits."  The Innsbruck group (Harald Weinfurter,
harald.weinfurter@uibk.ac.at) converts a single ultraviolet photon
into two photons whose properties are quantum mechanically
interlinked, or "entangled."  Devices then encode a 0, 1, or 2 onto
one of the photons by performing an operation on it (such as
flipping its spin or shifting its phase); since the devices are blind to
the initial state of the photon, they change the overall properties of
the entangled photon pair without determining its final state.  The
two photons are recombined and then the interlinked pair travels
towards a network of detectors.  Two-photon interference creates
three different sets of detection possibilities in the Innsbruck setup
that reveal the quantum state of the entangled pair and whether the
photon was encoded with a  0, 1, or 2.  The physics of
entanglement has been exploited in numerous recent experiments,
to build quantum logic gates (Update 250) and perform an atom-level demonstration of Schrodinger's cat (Update 273), but until
now it has never been used for quantum communication---encoding
a message at one location and receiving it at another. Furthermore,
the same information contained in a typical ASCII character,
normally requiring the use of 8 bits, can also be transmitted using
only 5 trits.  (K. Mattle et al, Physical Review Letters, 17 June
1996.  More information and graphics can be found at
http://www.uibk.ac.at/c/c7/c704/qo/photon/_qdc)

THE CLOSEST EXTRA-SOLAR PLANET yet discovered orbits
the star Lalande 21185, only 8.1 light years from Earth.  George
Gatewood of the University of Pittsburgh observed a telltale wobble
in the light coming from the star, indicating the presence of a
Jupiter-sized planet circling the star in a Saturn-sized orbit. 
Gatewood's data, presented at the meeting of the American
Astronomical Society in Madison, WI, even hinted at the possibility
of other planets in the same solar system. (Washington Post, 12
June.)  Also,  another planet has been found by Geoff Marcy of San
Francisco State and Paul Butler of Berkeley, who announced two
new planets in January 1996.  Their new find is a Jupiter-sized
planet orbiting the star Rho Cancri (40 light years from Earth) at a
distance of only 0.1 astronomical units.  It completes a "year" in
only about two Earth weeks.  (Sky & Telescope, July 1996)

A MOVIE OF THE CRAB NEBULA provides new details about
pulsar dynamics.  At the heart of the nebula is a pulsar (the remnant
of a 1000-year-old supernova) which casts powerful streams of
particles into the surrounding debris-filled medium.  The Hubble
Space Telescope has recorded a sequence of pictures which show
where much of the pulsar's energy goes.  One surprise was how
quickly the landscape alters: noticeable changes in the region around
the pulsar sometimes occurred in a matter of days.  A second
surprise is that the outward flow of energy is confined largely to
two zones: jets shooting out from the poles and wisps of material in
the pulsar's equatorial plane.  (Science News, 8 June; Science, 7
June.)