Apr 28 2010
The hands of a clock tell the whole story. Technical factors place limits on the precision of the reading. For physicists, so-called shot noise also imposes such a limit. It occurs for example when electric current has to overcome a barrier. At present, all precision measurements work close to this limit. Physicists from Heidelberg University have now demonstrated that this limit can be surpassed by drawing on concepts from quantum mechanics. They have published their findings in the online edition of Nature.
"To work close to this classical precision limit while drawing on the fundamental theory of quantum mechanics as it stands at the moment, we had to cool atomic gases to extremely low temperatures 0.000 000 01°K above absolute zero," reports Prof. Dr. Markus Oberthaler, head of the "Synthetic Quantum Systems" research group at Heidelberg University’s Kirchhoff Institute of Physics and co-author of the Nature study. The stability of the lab set-up was taken to such an extreme that read-off precision was defined by the classical shot-noise limit. To undercut that limit, quantum-mechanical resources were then generated via systematic manipulation of the microscopic interaction between the atoms. Professor Oberthaler refers to this newly developed method as "so outstanding that we were able to realise the worldwide biggest quantum-entangled system of 170 particles, ten times more particles than ever before. Subsequently measurements were performed that explicitly surpassed the classical precision limit in a way that was recognisable to the naked eye.
"It is by no means unlikely that this achievement in fundamental physics will have a bearing on our everyday lives. "We are already surrounded by precision physics," says Professor Oberthaler. "In almost every car there are navigation devices based on the principle of precise time measurement. At present this measurement is operating very close to the classical precision limit. If we want to improve the time standard, these findings point to a new way of doing so."
Source: Universität Heidelberg