Oxford physicists use atomic clocks to hunt for darkish matter

Scientists at the University of Oxford recently published the results of a mind-blowing experiment in which they entwined two atomic clocks at a record-breaking two meters apart.

In front: Atomic clocks have been in widespread use since the 1950s. They are used in myriad applications ranging from managing fairness in the stock market to enabling spacecraft to be navigated at extreme speeds.

The Oxford team’s experiment involved a relatively new wrinkle in the formula called the optical atomic clock.

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While traditional atomic clocks typically rely on exciting atoms (read: zapping them with microwaves) at precise frequencies, the optical variant uses a lattice of laser beams to trap and isolate individual atoms.

With the optical technique, the researchers essentially measure light-emitting atomic transitions in contrast to those that emit microwaves. This allows scientists to make more robust measurements.

What makes the Oxford team’s experiment exciting is that they became entangled two separate atomic clocks about two meters apart.

According to the team’s research paper:

Measurements on independent systems are limited by the standard quantum limit; Measurements on entangled systems can exceed the standard quantum limit to reach the highest precision allowed by quantum theory – the Heisenberg limit.

Background: Scientists have successfully entangled atomic clocks at the microscopic level, but to the best of our knowledge, this is the greatest distance at which two optical atomic clocks have ever been entangled.

In essence, the Oxford team have managed to create a two-node network of atomic clocks at a very useful distance – one that could theoretically be scaled up.

Furthermore, hypothetically speaking, there is no limit to the number or type of nodes that could be added to a network of entangled atomic clocks.

Scientists currently use a math-based consensus between tens or hundreds of different atomic clocks to get the most accurate readings possible. But entangled clocks are theoretically capable of much greater accuracy.

Take fast: The possible implications for this research are enormous. The more accurately we can measure the passage of time, the closer we can come to solving some of the universe’s greatest mysteries.

If we’re able to engineer a vast network of atomic clocks spreading out into space, it’s possible we could begin to construct a sort of inverted picture of the universe that reveals dark matter in real time.

US and Canadian researchers predicted the usefulness of such a network in a 2014 article detailing a dark matter detector based on synchronized atomic clocks:

During the encounter with an expansive dark matter object as it sweeps through the network, initially synchronized clocks become desynchronized. Time differences between spatially separated clocks are expected to have a unique signature that encodes the spatial structure of the defect and its interaction strength with atoms.

In other words, if dark matter is out there, the Oxford team’s recent breakthrough could be our best lead yet. And the best thing is that there are not many downsides to continuing this research. Even if the dark matter theory doesn’t work, there are countless practical applications for more accurate atomic clocks.

H/t: Mike Mcrae, Science Alert

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