wireless transmission of quantum code over a distance of 144,kilometers (89 miles)

Sean McGrath sean at manybits.net
Fri Mar 16 12:16:41 EDT 2007

-------- Original Message --------

The American Institute of Physics Bulletin of Physics News
Number 815   March 16, 2007 by Phillip F. Schewe, Ben Stein

kilometers (89 miles) between two Canary Islands has been
demonstrated by a team of researchers in Europe.  At the APS March
Meeting, Anton Zeilinger of the University of Vienna
(anton.zeilinger at univie.ac.at) described how he and his colleagues
transmitted single photons from an astronomical observatory in La
Palma Island to another one in Tenerife.  The transmitted photons'
polarization states (representing 0s and 1s) formed the basis of a
"quantum key," a stream of information that could be used to
decipher a longer encrypted message.  The researchers used single
photons because they are more secure than groups of photons, from
which an eavesdropper could pluck information about the key.  To
detect potential eavesdroppers even better, the researchers
entangled the outgoing particles of light with photons kept at the
transmitting station. They used astronomy stations because their
telescopes are sensitive enough to detect individual photons.  The
data transmission rate was low, only 178 photons in 75 seconds, but
the photons are able to travel longer distances in free space
(potentially thousands of kilometers or more) than they are in fiber
optic cables (100 km) before they become undetectable.  In a
proposed experiment to be coordinated by the European Space Agency
(ESA, which operates the Tenerife telescope and which participated
in the Canary Islands experiment) the International Space Station
can transmit entangled key to two earthbound stations separated by
distances ten times greater or more. (For a preprint, see Ursin et
al., quant-ph/0607182)

PHYSICS NEWS UPDATE is a digest of physics news items arising
from physics meetings, physics journals, newspapers and
magazines, and other news sources.  It is provided free of charge
as a way of broadly disseminating information about physics and
physicists. For that reason, you are free to post it, if you like,
where others can read it, providing only that you credit AIP.
Physics News Update appears approximately once a week.

AUTO-SUBSCRIPTION OR DELETION: By using the expression
"subscribe physnews" in your e-mail message, you
will have automatically added the address from which your
message was sent to the distribution list for Physics News Update.
If you use the "signoff physnews" expression in your e-mail message,
the address in your message header will be deleted from the
distribution list.  Please send your message to:
listserv at listserv.aip.org
(Leave the "Subject:" line blank.)

Sean McGrath
sean at manybits.net

The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at metzdowd.com

More information about the cryptography mailing list