Exotic state of matter propels quantum computing theory

July 23, 2014 by Anne Ju

So far it exists mainly in theory, but if invented, the large-scale quantum computer would change computing forever. Rather than the classical data-encoding method using binary digits, a quantum computer would process information millions of times faster through the use of quantum states of matter.

But there's a reason computers aren't in every home yet. Scientists are still working on how to make a computer do calculations reliably on the . Cornell physicists have come up with a key piece of the theoretical puzzle, bringing science one step closer to revealing the first quantum computer.

Abolhassan Vaezi, a Bethe postdoctoral fellow working with Eun-Ah Kim, associate professor of physics, authored a paper published earlier this month in Physical Review X that answers a long-standing problem in quantum computing. He made a "fractional topological superconductor," an exotic state of matter in which emergent quasi-particles perform quantum computations without error.

To work on quantum computing, physicists explore electronic interactions in two dimensions, where never-before-seen states of matter can exist. The states are exotic because particles can carry what's called fractional charges – that is, rather than being limited to a charge of 1 (1 electron), within two-dimensional planes, charges can have a value of, for example, 1/3. In this theoretical realm, quantum computation could become reality.

Scientists had already theorized that for a system to be robust and able to store data effectively, it would have to employ such fractionalized excitations of particles, some of which are called non-Abelian anyons. The simplest example of a non-Abelian anyon is called a Majorana fermion, which has been conjectured to exist in many physical systems and to form the basis for fault tolerance, meaning resistant to error.

In his paper, Vaezi demonstrates more efficient non-Abelian quasi-particles, Fibonacci anyons, through the use of a superconducting vortex, at the interface of a 2/3 fractional quantum Hall-superconductor structure. He demonstrates how this system undergoes a phase transition to the Fibonacci state that is the most coveted platform for building fault-tolerant quantum computers.

This discovery provides a novel mechanism for how to make universal topological quantum computers.

Explore further: Physicists move one step closer to quantum computer

More information: Abolhassan Vaezi. "Superconducting Analogue of the Parafermion Fractional Quantum Hall States." Phys. Rev. X 4, 031009 – Published 15 July 2014. DOI: 10.1103/PhysRevX.4.031009

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Steve 200mph Cruiz
5 / 5 (3) Jul 23, 2014
A lot of aspects of quantum mechanics remind me a lot of when chemistry was alchemy, nobody knew why chemical reactions worked, but something interesting usually happened when they messed around.
The alchemists never found out how to create gold, but as we learned about atomic structures because of these early chemists, we could now create gold if we really wanted to using the strong and weak forces, it just turns out to be a waste of every ones time haha.
I don't really care if the goal of a quantum computing is ever achieved, the discoveries made on the path to it will be even more profound and maybe in comparison, quantum computers as they are currently envisioned will be a waste of time, which is saying something.
Jul 24, 2014
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