Atomic timekeeping, on the go
What time is it? The answer, no matter what your initial reference may be — a wristwatch, a smartphone, or an alarm clock — will always trace back to the atomic clock. The international standard for time is set by atomic clocks — room-sized apparatuses that keep time by measuring the natural vibration of atoms in a vacuum. The frequency of atomic vibrations determines the length of one second — information that is beamed up to GPS satellites, which stream the data to ground receivers all over the world, synchronizing cellular and cable networks, power grids, and other distributed systems. Now a group at MIT and Draper Laboratory has come up with a new approach to atomic timekeeping that may enable more stable and accurate portable atomic clocks, potentially the size of a Rubik’s cube. The group has outlined its approach in the journal Physical Review A. While chip-sized atomic clocks (CSACs) are...