We won't be seeing it in a DeLorean any time soon, but a team of quantum physicists have succeeded in sending a simulated particle back in time. Using an IBM quantum computer and a 'time reversal' algorithm, the researchers reversed the particle's ageing by a millionth of a second.
It's an amazing achievement, but doesn't necessarily translate to time travel in the real world. The team were quick to point out that the circumstances necessary for the particle to take its virtual trip back through time are vanishingly unlikely to actually occur outside a simulation.
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“We demonstrate that time-reversing even ONE quantum particle is an insurmountable task for nature alone,” one of the physicists, Dr Valerii M Vinokur of Argonne National Laboratory, told the New York Times (opens in new tab).
One small step back for man...
Unlike the device you're reading this on, which processes a series of 0s and 1s called bits, a quantum computer uses subatomic particles called qubits, which can exist in multiple states at the same time (both 0 and 1). This means quantum computers can store much more information and compute issues much more quickly.
The IBM computer used by the research team (which is available online (opens in new tab) to the public) has just five qubits, only two or three of which were used for the time-reversal experiment.
The qubits were prepared in a way that simulated an 'artificial atom', then blasted with a pulse of microwaves that shifted them into a more complex state. This 'evolution process' lasted a millionth of a second.
A second microwave pulse reversed the phase, reverting the qubits to their original 'youthful' state and essentially turning back the clock.
Anyone hoping to build their own flux capacitor is out of luck, but it's still a fascinating breakthrough. “In graphic language, we convert spreading rings in the pond into the rings that are ready to go back to their origin,” Dr Vinokur said.