Boffins use radio waves to cool silicon micro-cantilever

US scientists from the National Institute of Standards and Technology (NIST) have used radio waves to cool silicon micro-cantilever. Cantilevers are created by ion etching through silicon.

Washington, Sept 16 : US scientists from the National Institute of Standards and Technology (NIST) have used radio waves to cool silicon micro-cantilever. Cantilevers are created by ion etching through silicon.

For years, scientists have used visible and ultraviolet laser light years to cool trapped atoms - and more recently larger objects - by reducing the extent of their thermal motion.

Now, applying a different form of radiation for a similar purpose, NIST physicists have used radio waves to dampen the motion of a miniature mechanical oscillator containing more than a quadrillion atoms.

Scientists say this is a cooling technique that may open a new window into the quantum world using smaller and simpler equipment.

There might 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, they said.

As part of their research, the scientists used a RF circuit to cool a 200 x 14 x 1,500 micrometer silicon cantilever - a tiny diving board affixed at one end to a chip and similar to the tuning forks used in quartz crystal watches - vibrating 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.

The research team now hopes to extend the RF method to higher frequencies at cryogenic temperatures, to 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 behaviour should emerge.

The study is scheduled for publication in a forthcoming issue of Physical Review Letters.

ANI