A quantum network of atomic clocks could create even more accurate and stable time-keeping devices than present atomic clocks, reports a paper published online this week in Nature Physics. Such a network could have technological applications as well as provide a resource for Earth science studies and fundamental tests of relativity and quantum gravity.

The modern world relies heavily on accurate time-keeping, for instance for the operation of the Global Positioning System, or synchronization in high-frequency financial trading.

Based on a combination of precision metrology and quantum technologies, Peter Komar, Mikhail Lukin and colleagues show that a network of atomic clocks sharing quantum entanglement would achieve a time-keeping stability better than that of any individual clock. Distributed around the Earth and on satellites, the clock network could maintain and synchronize time standards across multiple parties in real-time - a true world clock. Furthermore, by its very nature, this quantum network of atomic clocks would be protected against quantum-cryptographic attacks.