FW: Physics News Update 619

[Kossmann, Bill]

FYI (second article near the bottom of this message).

Bill


-----Original Message-----
From: physnews at aip.org [mailto:physnews at aip.org]
Sent: Friday, January 03, 2003 10:38
To: BKossmann at DTHR.AB.CA
Subject: Physics News Update 619


PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 619 January 3, 2003   by Phillip F. Schewe, Ben Stein, and James
Riordon

X-RATED INTERFEROMETRY. The appearance of an x-ray interference pattern in
a Fabry-Perot interferometer has been achieved, for the first time, by a
group of physicists at the University of Hamburg (Yuri Shvyd'ko,
yuri.shvydko at desy.de, 49-40-8998-2200). This might lead to a new
generation of x-ray optical devices, such as high-resolution x-ray spectral
filters, or x-ray clocks, and, more important still, a new way of
calibrating length measurements at the atomic scale. X-rays are a potent
type of electromagnetic radiation, with a much higher energy and smaller

[...]

the cavity, the spectral sharpness of the Fabry-Perot interference fringes
was estimated to be less than a micro-electron-volt. This is more than 100
times better than the best x-ray crystal monochromators can do. (Shvyd'ko et
al., upcoming article in  Physical Review Letters; accompanying figure will
be posted on Jan 6 at www.aip.org/mgr/png ; see also related PRL article, 17
July 2002; http://focus.aps.org/story/v6/st2 )

FEASIBLE CHAOTIC ENCRYPTION.   Encryption schemes that hide messages in
chaotic signals have attracted attention in recent years as a means to
transmit information securely (Update 170, 361), but most work has been
either theoretical or strictly limited to laboratory experiments. Now a
group of researchers in Beijing have managed to demonstrate chaotically
encrypted, two-way voice transmission through the Beijing Normal University
computer network. With a 32-bit encryption structure, a 750 MHz personal
computer can encode information at speeds comparable to the widely
recognized Advanced Encryption Standard, and support voice communication at
typical telephone speeds and quality. While no encryption technique is
absolutely impenetrable, the researchers (Hu Gang, Beijing Normal
University, hugang at sun.ihep.ac.cn, 86-10-62208420) explain that their
communication scheme is reasonably secure (it would take an intruder armed
with a personal computer more than a million times the lifetime of the
universe to break the code) as well as being feasible in realistic,
commercial settings. (S. Wang et al., Physical Review E, December 2002.)

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