MIT researchers show quantum entanglement could make atomic clocks more accurate

MIT researchers have designed a method that they say could help build the most precise atomic clock to date. Their approach could help scientists explore questions such as the effect of gravity on the passage of time and whether time changes as the universe gets older. More accurate atomic clocks would even be sensitive enough to detect dark matter and gravitational waves.

The researchers, who published their findings in a paper in Nature, used a different method from existing atomic clocks to achieve greater accuracy. Instead of measuring randomly oscillating atoms, their design centers around quantumly entangled atoms. The atoms are correlated in a way that's "impossible according to the laws of classical physics."

The team entangled around 350 atoms of ytterbium. The rare earth element's atoms oscillate at the same frequency as visible light, or 100,000 times more often per second than cesium, the element used in other atomic clocks. If scientists can track those oscillations precisely, they "can use the atoms to distinguish ever smaller intervals of time," MIT notes.

Were the most advanced atomic clocks adapted to use this method and they'd been around since the beginning of the universe (some 14 billion years ago), researchers believe they'd be accurate to within less than a tenth of a second. The most advanced atomic clocks would be off by around half a second over the same timeframe with their current setups.

Update (12/18): An earlier version of this article said researchers built an atomic clock based on this technique. According to the team, their goal is to build one, however so far “what we have done is a demonstration that quantum entanglement could help build the most precise clock.”