When Cher sang that he wanted to go back in time, she could have taken the career of a pop star and done quantum computer research if she really meant those words. This is a possible gift from a recent study by Scientific Reports. In the report physicists reveal how they could turn back the clock on a quantum computer by a fraction of a second. Well, so to speak.
Researchers from the United States, Russia and Switzerland sent a quantum bit (called Qbit) from a more complicated one to an earlier, simpler one. The work was done with an IBM quantum computer.
"Here we show that the complex conjugation necessary for time reversal is exponentially unlikely in nature, but one can design a quantum algorithm that includes complex conjugation and thus reverse a given quantum state," the researchers write in their abstract , "The use of this algorithm on an IBM quantum computer allows us to experimentally demonstrate reverse-time dynamics for a two-level electron."
As the MIT Technology Review magazine emphasizes, this is not . Reversal of the passage of time. It's more like rewinding a video and backtracking ̵
"At a fundamental level, we have elucidated the quantum mechanical origin of the irreversibility of time," said Valerii Vinokour, a researcher at the Argonne National Laboratory in Illinois, told Digital Trends. "The second law of thermodynamics states that a thermodynamic system can not develop backwards from the state of high entropy to the state of low entropy. Our novelty is that it turned out that even the simplest purely quantum mechanical state evolves with increasing complexity so that even the simplest pure quantum state can not spontaneously reverse its evolution.
In addition to some of the high-fideline questions on cosmology and the universe, the work could also have more immediate implications by helping to eliminate noise and errors from programs written for quantum computing.
Unfortunately, one thing does not seem to lead to a real working time machine for transporting people to build on the Back to the Future style jumps. "Not really, no contribution to the time travel concept," said Vinokour. "Time travel is a different and unrelated beast that I would refrain from commenting on."
Is not that what someone would say if had built a time machine? (Disclaimer: You really have not built one.)