Quantum Computer One Step Closer Thanks to Breakthrough

Researchers have succeeded in initializing and reading nuclear spins

Graphene is considered the next big thing in technology, thanks to the material's various traits, but it is still something that will improve on what already exists, instead of a new idea. The real leap forward will happen when quantum computers become reality.

A quantum computer is controlled by the laws of quantum physics and, in theory, should be able to carry out complicated calculations and large data searches at speeds far beyond those of today's best supercomputers.

Should everything finally fall into place, we may even be looking at desktop PCs that work better than building-sized conglomerates.

That is decades in the future though. In the meantime, we can only keep an eye on each small step forward.

Fortunately, the latest step isn't quite so small. Professor Weimin Chen and his colleagues at Linköping University have figured out how to initialize and read nuclear spins, relevant to qubits for quantum computers to room temperature.

The advantage of using the nuclear spin as a qubit is that the nucleus of an atom, made of both protons and neutrons, is well protected, nearly immune to electromagnetic disturbance.

Now, to finally enable quantum PCs, each qubit needs to be assigned a well-defined value, either 1 or 0. Then, all the atomic nuclei would have to spin in the same direction (clockwise or counterclockwise) in order to initiate spin-based qubits.

Strongly spin polarized electrons are key here, which function perfectly at lower temperatures. The spin orientation in the electrons can easily be lost at room temperature though.

With help from German and American colleagues, the team of researchers from Linköping University has solved the problem by making a spin filter that works at room temperature, by letting electrons with the desired spin through, but screening out the others.

“You could say that a quantum computer can think several thoughts simultaneously, while a traditional computer thinks one thought at a time,” said Weimin Chen, professor in the division of functional electronic materials at the department of physics, chemistry and biology at LiU.

“We prove experimentally that the measurable magnetic field from the nuclei, as well as the strong polarization of the nuclear spins in the material at room temperature, comes from the dynamic polarization of the nuclear spin in the extra added Ga atoms.”

The polarization of the nuclear spin happens very quickly, possibly in less than a nanosecond (one billionth of a second). Using free electrons allows controlling the polarization, thus letting the information be both initiated and read.

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