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SciTech

'Time crystal' computer can outlive the universe, works on Gallifrey


Scientists have devised a computing device that can theoretically outlive the universe and continue working long after the last star in existence has called it a night.
Shades of Gallifrey! Talk about Time Lord technology.   
Theoretical physicist Frank Wilczek has speculated about the computing capabilities of "time crystals": structures that exhibit repeating patterns not just in the usual spatial dimensions but also in the fourth dimension, time, New Scientist reported.
Computing with time crystals  
If a working time crystal could be made into a computer, it would have rotational states standing in for the 0s and 1s of a conventional computer, the report said.
 
"To make it interesting you want to have different kinds of ions, maybe several rings that affect each other. You can start to think about machines that run on this principle," he said.
 
But building the crystal will be difficult as it needs temperatures close to absolute zero, the New Scientist article said.
 
New Scientist said that to translate the spatial symmetry of a regular crystal into the fourth dimension, the atoms in such a "time crystal" would have to constantly rotate and return to their original location.
 
Also, they would also have to be in their lowest possible energy state, meaning that they would naturally continue to rotate even after the universe's "heat death" —when it will have succumbed to entropy and cooled to a uniform temperature.
 
Superconducting ring
 
Wilczek originally suggested that a superconductive ring could serve as a time crystal if electrons could be made to flow separately rather than in a continuous stream.
 
Although this would ensure a repeating pattern, he could not quite figure out how to do so in practice.
 
That may change soon, as Tongcang Li at the University of California, Berkeley, and colleagues at the University of Michigan in Ann Arbor and Tsinghua University in Beijing, China, have an alternative suggestion that may be possible to build.
 
A first requirement is an ion trap, a device that holds charged particles in place using an electric field.
 
This causes the ions to form a ring-shaped crystal, since ions trapped at extremely low temperatures repel each other.
 
One can then apply a weak static magnetic field, which causes the ions to rotate.
 
Under the laws of quantum mechanics, the rotational energy of the ions must be greater than zero, even when the ring is cooled to its lowest energy state.
 
In such a state, the electric and magnetic fields are no longer needed to maintain the shape of the crystal and the spin of its constituent ions.
 
This results in a time —or, rather, space-time— crystal, because the ion ring now repeats in space as well as in time.
 
"I'm very pleased with it. They've really come up with something that looks like a realizable experimental design," said Wilczek. Theoretical challenges
 
However, building the crystal may pose a challenge as it needs temperatures close to absolute zero to work properly.
 
"The main challenge will be to cool an ion ring to its ground state," said Xiang Zhang, a member of the team who is also at Berkeley.
 
But Xiang said this should be possible in the near future as ion trap technologies improve. So far, there have been no inquiries reported from anyone matching the description of a well-dressed man in a blue box. — TJD, GMA News
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