[108155] in Cypherpunks
CDR: update.413 (fwd)
daemon@ATHENA.MIT.EDU (Jim Choate)
Sat Feb 6 17:39:08 1999
From: Jim Choate <ravage@einstein.ssz.com>
To: cypherpunks@einstein.ssz.com
Date: Sat, 6 Feb 1999 16:14:31 -0600 (CST)
Reply-To: Jim Choate <ravage@einstein.ssz.com>
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Date: Thu, 4 Feb 1999 11:03:43 -0500 (EST)
From: AIP listserver <physnews@aip.org>
Subject: update.413
PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 413 February 4, 1999 by Phillip F. Schewe and Ben
Stein
THE FIRST 3D PHOTONIC CRYSTAL operating at a
wavelength of 1.5 microns, the all-important preferred wavelength
for light traveling down optical fibers, has been devised by
scientists at Sandia (Shawn Lin, slin@sandia.gov). Basically, a
photonic crystal is to light what a semiconductor is to electrons:
some photon energies are permitted while others are excluded.
The exclusion comes about by a careful interleaving of materials
with very different indices of refraction. The Sandia crystal is
actually a tiny pile of criss-crossed polysilicon rods with air in
between. Photonic crystals will be ingredients in future optical
transistors---by deflecting light they will be able to act as optical
switches at THz speeds; by trapping light they will be able to
produce optical amplification within cavities. The crystals will
also be part of other optical integrated circuit components such as
low-power nanolasers and as waveguides. (Optics Letters, 1 Jan
1999; see also Physics Today, Jan 1999.)
MAGNETOELECTRONICS, SPIN ELECTRONICS, AND
SPINTRONICS are different names for the same thing: the use of
electrons' spins (not just their electrical charge) in information
circuits. One magnetoelectronic device is the magnetic hard drive
based on the giant magnetoresistance (GMR) effect. In a GMR
material, consisting of a stack of alternating layers of magnetic and
nonmagnetic atoms, a small magnetic field can produce a large
change in electrical resistance. Already a billion dollar business,
GMR read heads will boost disk drive densities from 1 to 20 Gbits,
and GMR might be incorporated into random access memory units
as well (Gary Prinz, Science, 27 Nov 1998). The latest
demonstration of spin versatility is the organized movement of a
herd of spins over a lateral distance of 100 microns. In an
experiment at UC Santa Barbara, David Awschalom first aligned
the spins of a swarm of electrons and then nudged them across a
semiconductor strip without the spin bunch falling apart. Such
coherence will be necessary if spin currents are to transport
information from place to place, particularly in quantum
computers. (Nature, 14 Jan 1999.)
THE ROLE OF PHYSICS IN BIOLOGY is a venerable one. The
[text deleted]
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There is a coherent plan in the universe, though
I don't know what it's a plan for.
Fred Hoyle
The Armadillo Group ,::////;::-. James Choate
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