Skip to comments.'Radio wave cooling' offers new twist on laser cooling
Posted on 09/15/2007 6:11:31 PM PDT by ckilmer
Public release date: 14-Sep-2007
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Contact: Laura Ost
National Institute of Standards and Technology (NIST)
Visible and ultraviolet laser light has been used for years to cool trapped atomsand more recently larger objectsby reducing the extent of their thermal motion. Now, applying a different form of radiation for a similar purpose, physicists at the National Institute of Standards and Technology (NIST) have used radio waves to dampen the motion of a miniature mechanical oscillator containing more than a quadrillion atoms, a cooling technique that may open a new window into the quantum world using smaller and simpler equipment.
Described in a forthcoming issue of Physical Review Letters,* this demonstration of radio-frequency (RF) cooling of a relatively large object may offer a new tool for exploring the elusive boundary where the familiar rules of the everyday, macroscale world give way to the bizarre quantum behavior seen in the smallest particles of matter and light. There may be technology applications as well: the RF circuit could be made small enough to be incorporated on a chip with tiny oscillators, a focus of intensive research for use in sensors to detect, for example, molecular forces.
The NIST experiments used an RF circuit to cool a 200 x 14 x 1,500 micrometer silicon cantilevera tiny diving board affixed at one end to a chip and similar to the tuning forks used in quartz crystal watchesvibrating at 7,000 cycles per second, its natural resonant frequency. Scientists cooled it from room temperature (about 23 degrees C, or 73 degrees F) to -228 C (-379 F). Other research groups have used optical techniques to chill micro-cantilevers to lower temperatures, but the RF technique may be more practical in some cases, because the equipment is smaller and easier to fabricate and integrate into cryogenic systems. By extending the RF method to higher frequencies at cryogenic temperatures, scientists hope eventually to cool a cantilever to its ground state near absolute zero (-273 C or -460 F) , where it would be essentially motionless and quantum behavior should emerge.
Laser cooling is akin to using the kinetic energy of millions of ping-pong balls (particles of light) striking a rolling bowling ball (such as an atom) to slow it down. The RF cooling technique, lead author Kenton Brown says, is more like pushing a child on a swing slightly out of synch with its back-and-forth motion to reduce its arc. In the NIST experiments, the cantilevers mechanical motion is reduced by the force created between two electrically charged plates, one of which is the cantilever, which store energy like electrical capacitors. In the absence of any movement, the force would be stable, but in this case, it is modulated by the cantilever vibrations. The stored energy takes some time to change in response to the cantilevers movement, and this delay pushes the cantilever slightly out of synch, damping its motion.
* K.R. Brown, J. Britton, R.J. Epstein, J. Chiaverini, D. Leibfried, and D.J. Wineland. 2007. Passive cooling of a micromechanical oscillator with a resonant electric circuit. Physical Review Letters. [Forthcoming].
Exactly what I was hoping for. This changes everything.
"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus
Yep. The entire world as we perceive it doesn't exist. It's all just a dream. Wait a minute, that means this discovery is part of a dream too...
Yep. The entire world as we perceive it doesn’t exist. It’s all just a dream.
And the dreamers themselves are just part of the dream. I think someone once said that reality is the one illusion that we all share. But, then, on the other hand, we don’t actually all share it. I think I will start drinking beer by the case again, somehow things seemed more simple then.
This sounds like the opposite of microwaves heating things up.....
Or radio waves.
“Reality is merely an illusion, albeit a very persistent one.”
- Albert Einstein
This is different, I’ll need to read it later, bmflr.
Department of Physics and Astronomy, Georgia State University
post-1985 | Carl R. (Rod) Nave
Posted on 12/28/2004 12:57:07 PM EST by SunkenCiv
ANOTHER COOL IDEA FROM TEXAS
(Physicists at UT Discovered “quantum refrigerator” to Cool Atoms)
U-WIRE | Aug. 10, 2005 | Amanda Pinkston
Posted on 08/13/2005 5:13:42 PM EDT by nickcarraway
Reflections of Absolute Zero
ScienceNOW Daily News | 9 April 2007 | Phil Berardelli
Posted on 04/10/2007 12:46:53 AM EDT by neverdem
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