“Through these links, Hearst Magazines and Yahoo may earn a commission or revenue for some items.”
Here’s what you’ll learn in this story:
-
Atomic clocks will lose only 1 second in accuracy in 10 million years. They are used in many ways, including the GPS in your car.
-
Now scientists have found a way to bypass the laws of quantum physics and create a significantly more stable and accurate atomic clock.
-
In the future, such a device could allow us to precisely navigate interstellar travel, or be a tool for predicting earthquakes or studying dark matter in greater detail.
It’s a beautiful, sunny day and you’re driving up and down the highway, getting directions from your phone’s super-accurate GPS mapping app. Although these automatic references may seem effortless, they are actually the result of signals sent to satellites more than 12,000 miles above you.
Inside each of these satellites is the beating heart of an atomic clock.
Unlike the wall clocks you might find in your grandmother’s kitchen, atomic clocks keep extremely accurate time by tracking the movement of electrons in atoms. They measure the frequencies of electromagnetic radiation required for an electron to jump energy levels or oscillate in atoms of elements such as rubidium or strontium. While less accurate clocks will experience a noticeable change in accuracy over time, an atomic clock will only lose 1 second in accuracy over 10 million years.
In addition to being powerful tools for measuring time and navigating distant environments, even interstellar space, atomic clocks of the future could be used to explore fundamental scientific questions, such as understanding dark matter or predicting when earthquakes will occur.
Yet for all its strengths, scientists are not yet satisfied with what atomic clocks can do. Scientists are working to create atomic clocks that could be more accurate and more portable. To achieve these goals, they use the methods of quantum mechanics, the physics of the smallest particles of matter, atoms and subatomic particles.
“All these clocks are essentially quantum,” he said Vladan VuletićPh.D., professor of physics at MIT. This is because these systems are designed to detect and measure the atomic and subatomic movement of atoms inside clocks.
Two recently published studies Nature and Scientific progress explored quantum techniques that could improve the accuracy of atomic clocks. Vuletić is the senior author Nature research that used quantum mechanical techniques to improve the stability of atomic clocks in a subspecies of ultra-precise clocks called optical atomic clocks.
In these clocks, the ytterbium atoms oscillate at an even higher frequency than standard atomic clocks, so they can measure time intervals as small as 100 trillionths of a second.
But their precision also makes them susceptible to quantum distortions known as “noise,” which make it difficult to measure the vibrations of atoms. You can think of it as hitting a “quantum limit,” Vuletic said. It’s an idea related to the Heisenberg Uncertainty Principle, which dictates that there is a limit to how much you can know or measure about a quantum system, specifically what physical properties of a particle you can measure. If you identify one property accurately, you will know another property less accurately.
In their work, Vuletić and colleagues demonstrated that entanglement of ytterbium atoms inside the clock with high-oscillation laser light allows double the precision of an optical atomic clock.
“If you increase the number of particles, your accuracy will be better… [but] you always have a finite number of particles, Vuletić said. – With quantum mechanics [entanglement]… you can design future clocks that work better for a given number of particles. Entanglement, or correlation as some physicists like to call it, is a quantum phenomenon in which particles bind to each other, even when they are at large distances, so that measuring a property of one particle is instantly replaced by another. This Einstein timidly called “spooky action at a distance.”
Physicists from the University of Sydney in Australia have taken a different approach to this problem of overcoming the quantum limit. Their works were published in Scientific progress seems to – but not quite – turn the rules of quantum mechanics on their head. In this paper, the researchers demonstrated a way to precisely measure both the position and momentum of a quantum system simultaneously while maintaining Heisenberg’s uncertainty principle.
This is possible because the protocol focuses on measuring small changes at high levels of sensitivity, ignoring larger, “global” information about the system. The researchers liken it to trying to read an analog watch that only has a minute hand; you can know the information about what time it is very precisely, but the information about what time it is will be lost.
“Another way to explain it is that we’re actually throwing information away,” said the first author Kristof ValahuPhD. “We only care about very small changes, so we can get to this new uncertainty and bypass the Heisenberg Uncertainty Principle.”
This work has many applications for improving quantum sensing, including improving the accuracy of atomic clocks, said the senior author, Tingrei Tandoctoral degree, email
An emerging subspecies of atomic clocks that use highly charged ions can achieve greater accuracy than clocks based on strontium or ytterbium, Tan said, but it is much more difficult to measure these clocks directly.
“To get around it, they rely on a technique called quantum logic spectroscopy… [which] Tan, a quantum physicist at the University of Sydney, Australia, relies on the precise measurement of small displacements of position and momentum. [these] small shifts”.
While space-based GPS is still a long way off for interstellar missions, these types of clocks could certainly play a role, Vuletić and Tan said. This could look like pinging a network of atomic clocks in space, or even wearing a watch on board during missions. Whether you’re on Earth or in space, good timekeeping is essential for navigation, Tan said. Highly accurate and stable atomic clocks will help calculate the spacecraft’s current location “accurately” and even enable autonomous navigation.
No matter what the future holds for interstellar GPS or atomic clocks, Tan said there’s never been a better time to explore the quantum science behind the technology.
You may also like it