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Date: Thu, 17 Feb 2011 20:21:32 -0500
From: "James M. Atkinson" <jm..._at_tscm.com>
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Organization: Granite Island Group
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Subject: Researchers use magnets to tune supercooled gallium arsenide semiconductors
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The use of super magnets to do impressive things to TSCM antennas has
been around for a while, but Dr. Du's research takes this same thing to
the detector itself to tweak the systems to well over 100 GHz.
I own a number of these magnets, and they are way more powerful than a
refrigerator magnet and one can shoot across the room and kill someone
if they get away from you. The cool trick it to drop a paper clip to the
floor six feet away from one of these magnets and watch it shoot across
the room like a bullet when the magnetic field grabs it.
-jma
http://www.rfglobalnet.com/article.mvc/Rice-Physicists-Discover-Ultrasensitive-0001?user=205614&source=nl:29497
Rice Physicists Discover Ultrasensitive Microwave Detector
December 9, 2010
Researchers use magnets to tune supercooled gallium arsenide semiconductors
Physicists from Rice University and Princeton University have discovered
how to use one of the information technology industry's mainstay
materials - gallium arsenide semiconductors - as an ultrasensitive
microwave detector that could be suitable for next-generation computers.
The discovery comes at a time when computer chip engineers are racing
both to add nanophotonic devices directly to microchips and to boost
processor speeds beyond 10 gigahertz (GHz).
"Tunable photon-detection technology in the microwave range is not
well-developed," said Rice physicist Rui-Rui Du, the study's lead
author. "Single-photon detectors based on superconductors in the 10-GHz
to 100-GHz range are available, but their resonance frequency has been
difficult to tune. Our findings suggest that tunable single-photon
detection may be within reach with ultrapure gallium arsenide."
The study, which is available online and due to appear in print this
week in Physical Review Letters, is the latest result from a long-term
collaboration between Du and Princeton University physicist Loren
Pfeiffer, whose group produces the world's purest samples of gallium
arsenide. For the new study, Rice graduate student Yanhua Dai cooled one
of Pfeiffer's ultrapure samples to below 4 degrees Kelvin -- the
temperature of liquid helium. She then bombarded the sample with
microwaves while applying a weak magnetic field -- approximately the
same strength as that of a refrigerator magnet. Du and Dai were
surprised to find that microwaves of a specific wavelength resonated
strongly with the cooled sample. They also found they could use the
magnet to tune this resonance to specific microwave frequencies.
Du said previous experiments have typically measured weak resonance
effects from microwaves. "A signal level of 1 percent is a common
measurement. In our case, the change was a thousand times that much."
While the team does not yet understand the mechanism that leads to such
a sensitive reaction, they are eagerly pursuing follow-up research to
try to prove they can use the effect for single-photon measurements.
A photon is the smallest possible unit of light or electromagnetic
radiation. By incorporating devices that create, transmit and measure
digital information via photons, rather than with electrons, makers of
computer chips hope to produce computers that are both faster and more
powerful.
"The clock speed of a new computer right now is about 2 GHz," Du said.
"For the next generation, the industry is shooting for around 100 GHz,
which is a microwave device. The phenomenon we've observed is in this
region, so we hope it may be useful for them."
Additional co-authors include Princeton scientist Ken West. The research
was supported by the National Science Foundation.
SOURCE: Rice University
--
James M. Atkinson
President and Sr. Engineer
"Leonardo da Vinci of Bug Sweeps and Spy Hunting"
Granite Island Group
jm..._at_tscm.com
http://www.tscm.com/
(978) 546-3803
Received on Sat Mar 02 2024 - 00:57:15 CST