Scientists Say They Can Reverse Time in a Quantum System

An international team of scientists claim to have found a way to speed up, slow down, and even reverse the clock of a given system by taking advantage of the unusual properties of the quantum world, Spanish newspaper El País reports.

In a series of six papers, the team from the Austrian Academy of Sciences and the University of Vienna detailed their findings. The familiar laws of physics don't map intuitively onto the subatomic world, which is made up of quantum particles called qubits that can technically exist in more than one state simultaneously, a phenomenon known as quantum entanglement.

Now, the researchers say they've figured out how to turn these quantum particles' clocks forward and backward.

"In a theater, [classical physics], a movie is projected from beginning to end, regardless of what the audience wants," Miguel Navascués, a researcher at the Austrian Academy of Sciences' Institute of Quantum Optics and Quantum Information who worked on the research, told El País.

"But at home [the quantum world], we have a remote control to manipulate the movie," he added. "We can rewind to a previous scene or skip several scenes ahead."

"We have made science fiction come true!" the researcher exclaimed.

By developing a "rewind protocol," the team says they were able to revert an electron to a previous state. In experiments, they say they were able to demonstrate the use of a quantum switch to revert a photon to its original state before passing through a crystal.

While it's an exciting prospect, scaling up the technique could prove extremely difficult, if not impossible.

"If we could lock a person in a box with zero external influences, it would be theoretically possible," Navascués told El País. "But with our currently available protocols, the probability of success would be very, very low."

And there's an even bigger catch as well.

"Also, the time needed to complete the process depends on the amount of information the system can store," Navascués added. "A human being is a physical system that contains an enormous amount of information. It would take millions of years to rejuvenate a person for less than a second, so it doesn’t make sense."

Besides, the system is only able to revert the state of a given particle. To speed up time, though, the researchers have an ace up their sleeves.

"We discovered that you can transfer evolutionary time between identical physical systems," Navascués explained. "In a year-long experiment with ten systems, you can steal one year from each of the first nine systems and give them all to the tenth."

Instead of recreating "Back to the Future," the researchers see more mundane practical applications of their discovery. For instance, qubit states of a quantum processor could be reversed, effectively allowing researchers to undo errors during their development.

More on the quantum world: Aliens May Be Creating Black Holes to Store Quantum Information, Scientists Say

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