Quantum physicists at the University of Colorado Boulder and the National Institute of Standards and Technology (NIST) have made a breakthrough in optical atomic clocks by leveraging the power of quantum entanglement. This advancement could lead to the development of new quantum technologies, including sensors that can measure subtle changes in the environment, such as shifts in Earth’s gravity with elevation.
Quantum Clocks with the Help of Entanglement
It would be a room full of grandfather clocks, all ticking at different speeds. Now think at the atomic level of that scenario. Indeed, this is what quantum physicists have accomplished by embodying a wide variety of “clocks” in just one clock.
The research team made their groundbreaking device by trapping and cooling down a cloud of strontium atoms before shooting it with an intense laser. That spinning process causes the electrons whirling in circular orbits around the atoms to jump between energy levels, and this results in a kind of natural “ticking” that happens more than a trillion times a second. So all the researchers have to do is make a four-pack of these atoms quantum entangle–linking groups of them such that if you know one, you also know three more 14 meters away—that in effect creates a single clock out of four.
Quantum Mechanical clock Limit Pushed
That number might seem overly precise, but optical atomic clocks are extremely sensitive — the instruments have been able to detect differential levels of gravity as small as a fraction of a millimeter. Yet these systems must operate amidst the intrinsic uncertainty of quantum physics which can constrain their ability to measure time down to small fractions of a second.
This is due in part to their research’s discovery that quantum entanglement can enable certain measurements that cannot be performed between far distant points. Through their creation of entangled pairs, groups of four, and even groups of eight atoms, the team showed that this type of collective behavior can exist in a realm where too few individual atoms lead only to chaos. That means the entangled clocks would be able to reach a precision over a shorter period, something he calls “the Holy Grail” for optical atomic clocks.
THE KEY OF THE FUTURE: Quantum Technology
Their breakthrough has implications well beyond timekeeping. The technique for creating and manipulating quantum entanglement at the atomic level could lead to new quantum technologies such as more advanced sensors and machines.
The optical atomic clock’s entanglement methods, for instance, could potentially serve as “multi-qubit gates” — the very basics any quantum computer would need. Someday, the devices could even beat traditional computers at certain tasks, potentially upending fields such as cryptography, materials science, and drug discovery.
As Kaufman describes, these quantum systems promise that they can be “designed” with properties we have never seen before anywhere in the universe — and there are a lot of tunable knobs to twist for future technology. Even though the current clock only works for roughly 3 milliseconds, this novel work by the team lays a foundation to move even deeper into what it takes to control things at the quantum frontier.
