Quantum timekeeping
Physicists are exploring the mind-blowing possibilities of linking a new generation of atomic clocks
QUANTUM TIMEKEEPING Atomic clocks are so precise that physicists can measure time to the quintillionth (10-18) of a second with confidence. An entangled clock could do even better.
S. Egts
The best clock in the world has no hands, no pendulum, no face or digital display. It’s a jumble of lasers, wires and strontium atoms in Jun Ye’s lab at the National Institute of Standards and Technology (NIST) in Boulder, Colo. He keeps it cooled to about three millionths of a degree above absolute zero.
The clock, described by Ye in the Feb. 6 Nature, is so precise that had it begun ticking when Earth formed 4.5 billion years ago, it would not yet have gained or lost a second. Over that span, a Swiss quartz watch would stray at least a few thousand years.
Ye’s atomic, or optical, clock is impressive, but it’s just one step toward an ambitious timekeeping goal. He and his colleagues at JILA, a joint institute of NIST and the University of Colorado Boulder, envision 10 or more atomic clocks, installed in satellites and international labs, and
