Using ‘spooky action at a distance’ to link atomic clocks

An experiment carried out by the University of Oxford researchers combines two unique and one can say even mind-boggling discoveries, namely, high-precision atomic clocks and quantum entanglement, to achieve two atomic clocks that are “entangled.” This means the inherent uncertainty in measuring their frequencies simultaneously is highly reduced. “If you can measure the frequency difference between these two clocks that are in different locations, that opens up a host of applications,” says Raghavendra Srinivas, from the Department of Physics, Clarendon Laboratory, University of Oxford, U.K., who is an author of the Nature paper. Their work is a proof-of-principle demonstration that two strontium atoms separated in space by a small distance, can be pushed into an “entangled state” so that a comparison of their frequencies becomes more precise. Dr. Srinivas says, “The key development here is that we could improve the fidelity and the rate of this remote entanglement to the point where it’s actually useful for other applications, like in this clock experiment.” For their demonstration, the researchers used strontium atoms for the ease in generating remote entanglement.