Scientists at Copenhagen University's Niels Bohr Institute claim to have developed a technique that allows them to use a laser to cool a semiconductor membrane to -269°C.
Published in Nature Physics, the research saw the team at the Institute apply laser technology to the macro world, a feat that has never been achieved before.
Professor Eugene Polzik explained that this would mean "entirely new possibilities for what is called optomechanics, the interaction between optical radiation … and a mechanical motion".
To cool a single atom it is necessary to move the atom towards the laser, at which point the photon striking the atom will slow it down. And once the atom has been impacted to a sufficient extent, its momentum is reduced to near-zero, meaning it would have a temperature of absolute zero.
But frustratingly, this approach only works for atoms travelling towards the laser. Indeed, when the atom is travelling in the same direction as the laser, it simply gains momentum and ultimately heats up.
Although various techniques have been recommended previously to help cool more than one atom at a time, there has been no consistently successful approach. Until now, perhaps.
That's because the research team at Niels Bohr claim to have made a significant breakthrough. Since 2009, the team has worked with gallium arsenide, trying to create a semiconducting membrane with the right dimensions to use in their experiments.
The membrane is more than one square millimeter and only 160 nanometers thick, and according to the research team, it boasts the necessary resonant properties to be subjected to laser cooling.
Explaining the experiment, Koji Usami, an associate professor, said: "We let the membrane interact with the laser light in such a way that its mechanical movements affected the light that hit it.
"We carefully examined the physics and discovered that a certain oscillation mode of the membrane cooled from room temperature down to minus 269° C, which was a result of the complex and fascinating interplay between the movement of the membrane, the properties of the semiconductor and the optical resonances."
Mr Usmai suggested that the new approach could prove useful for cooling components in quantum computers. Additionally, he said that the innovation could be used to create new electrical or mechanical sensors.
