NASA Research Improves Atomic Clocks

NASA Tech Briefs, Mar 2004

NASA-funded researchers are using a property of quantum mechanics called entanglement to improve atomic clocks. Entangled clocks could be as much as 1,000 times more stable than their non-entangled counterparts. This improvement would benefit pilots, farmers, hikers, and anyone else using the Global Positioning System (GPS). Each of the GPS satellites carries four atomic clocks. By triangulating time signals broadcast from orbit, GPS receivers on the ground can pinpoint their own location on Earth.

Through its Office of Biological and Physical Research, NASA recently awarded a grant to Alex Kuzmich, a physicist at the Georgia Institute of Technology, to study how quantum entanglement can be applied to atomic clocks. "The ability to measure time with very high precision is an invaluable tool for scientific research and for technology," Kuzmich said.

Two entangled particles can appear to influence each other instantaneously, whether they are in the same room or at opposite ends of the universe. Quantum entanglement occurs when two or more particles interact in a way that causes their fates to become linked. Collectively, they constitute a single quantum state.

Entangling the atoms in an atomic clock, Kuzmich explained, reduces the inherent uncertainties in the system. In an entangled atomic clock, precision is directly proportional to the number of atoms, so four times more atoms means a four-times better clock. Kuzmich plans to use the lasers already built into atomic clocks to create the entanglement.

For more information, visit http://science.nasa.gov/headlines/ y2004/23jan_entangled.htm; contact Alex Kuzmich at alex. kuzmich@physics.gatech.edu.