Entanglement Protocol May Improve Synchronization of Atomic Clocks

In the June 4 issue of Science, physicists at the National Institute of Standards and Technology in Boulder, Colo., report an entanglement setup that promises applications in atomic clocks. The method combines approaches from precision spectroscopy and quantum information to improve the signal-to-noise ratio in the output signal.

Using pulses from two ultraviolet lasers, the researchers created a three-particle entangled system of beryllium ions. The ions were exposed to two detuned laser beams that acted as a phase gate for encoding quantum state information. After 2 µs, the scientists applied a decoding pulse to the system and recorded the total fluorescence, representing the quantum state of the ions, as a function of the offset phase.

Averaging the results of 1000 such experiments, they found that the performance of the apparatus was 45 percent better than could be expected from an ideal setup that employed three nonentangled particles. The approach is scalable to systems with a greater number of particles, and the researchers hope that it may be used to reduce the time required to synchronize atomic clocks.