Thursday, March 06, 2008
Quantum clocks were recently harnessed to outperform current atomic clocks by 10 times at the National Institute of Standards and Technology (NIST). By coupling the quantum states of trapped ions (electrically charged atoms), their natural vibration frequencies were synchronized to 17 digits of accuracy-the most ever measured. Based on aluminum and mercury ions, the new clocks stay accurate to within 1 second every billion years, compared with 80 million years for the current atomic-clock standard at NIST. According to NIST, such ultra-accurate clocks are useful for synchronizing telecommunications networks, space navigation, satellite positioning and deep-space communications, and could enable new types of gravity sensors for exploring underground natural resources here on Earth. Physicists also hope to use the new clocks to plumb cosmological mysteries, such as whether the ultimate yardstick in nature--the fine-structure constant (a dimensionless quantity that characterizes the strength of electromagnetic interactions)--is changing over time.
Posted by R. Colin Johnson at 11:32 AM