Semiconductor cooling with the help of quantum and nanophysics: Research

Researchers have devised a new way to cool semiconductors by using the combination of quantum physics and nanophysics.

This research has been done by researchers at the Niels Bohr Institute, University of Copenhagen, and published online in January 22 issue of the journal of Nature Physics.

Koji Usami working in lab

“In experiments, we have succeeded in achieving a new and efficient cooling of a solid material by using lasers.  We have produced a semiconductor membrane with a thickness of 160 nanometers and an unprecedented surface area of 1 by 1 millimeter. In the experiments, 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 degrees 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,” explains Koji Usami, associate professor at Quantop at the Niels Bohr Institute.

Researchers have cooled gas clouds of cesium atoms to about near absolute zero minus 273 degrees centigrade with the help of focused lasers and have developed entanglement between two atomic systems.

“For some time we have wanted to examine how far you can extend the limits of quantum mechanics – does it also apply to macroscopic materials? It would mean entirely new possibilities for what is called optomechanics, which is the interaction between optical radiation, i.e. light, and a mechanical motion,” explains Professor Eugene Polzik, head of the Center of Excellence Quantop at the Niels Bohr Institute at the University of Copenhagen.

“Efficient cooling of mechanical fluctuations of semiconducting nanomembranes by means of light could also lead to the development of new sensors for electric current and mechanical forces. Such cooling in some cases could replace expensive cryogenic cooling, which is used today and could result in extremely sensitive sensors that are only limited by quantum fluctuations,” Professor Polzik added.


K. Usami, A. Naesby, T. Bagci, B. Melholt Nielsen, J. Liu, S. Stobbe, P. Lodahl & E. S. Polzik, (2012). Optical cavity cooling of mechanical modes of a semiconductor nanomembrane. doi:10.1038/nphys2196

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