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Newly Discovered State of Matter Could Be a Breakthrough for Quantum Computing

Quantum spin liquids seem to defy the laws of nature.

by Sarah Emerson
Apr 4 2016, 8:07pm

Image: Getty/PM Images

Physicists have finally detected the existence of a mysterious new state of matter known as quantum spin liquid in a real material.

This new discovery is not only exciting in its own right, it presents vast possibilities for the future of quantum computing. Physicists at the Massachusetts Institute of Technology have theorized that quantum spin liquids could help to store data, improve calculations, and prevent the decay of the crux of quantum computing called the "qubit."

Quantum spin liquids, according to an MIT professor, could potentially eliminate the impurities in material around qubits that can cause it to change its quantum state unexpectedly.

Excitation of a spin liquid on a honeycomb lattice with neutrons. Image: Genevieve Martin, Oak Ridge National Laboratory

"It's an important step for our understanding of quantum matter," said co-author Dr. Dmitry Kovrizhin, a condensed matter theorist at the University of Cambridge, in a statement. "It's fun to have another new quantum state that we've never seen before—it presents us with new possibilities to try new things."

An international team of researchers theorized quantum spin liquids 40 years ago, and their existence was first discovered back in 2012 when physicists from the National Institute of Standards and Technology confirmed the presence of a spin liquid state in a mineral called Herbertsmithite.

Quantum spin liquids, according to the new study published in the journal Nature Materials, are known for their property of electron splitting, but researchers had never observed this take place in a real material. This new state of matter causes electrons—"thought to be indivisible building blocks of nature"—to break apart into fractional particles called Majorana fermions, which physicists were recently able to detect in a two-dimensional material similar to graphene.

"Until recently, we didn't even know what the experimental fingerprints of a quantum spin liquid would look like," said Dr. Kovrizhin. "One thing we've done in previous work is to ask, if I were performing experiments on a possible quantum spin liquid, what would I observe?"

Researchers were able to use neutron scattering techniques to successfully match their results to those of one of the main theoretical models for quantum spin liquids called the Kitaev model, the study says.

In order to understand the way quantum spin liquids function, you can think about the way that normal magnetic materials work. In magnetic materials, electrons will act as rotating bar magnets that align themselves according to their poles when cooled down to a low enough temperature.

However, in a magnetic material containing a spin liquid state, those electrons will constantly fluctuate and "even if that material is cooled to absolute zero, the bar magnets would not align but form an entangled soup caused by quantum fluctuations," researchers found.

To detect these fluctuations, physicists observed the electrons in their test material, alpha-ruthenium chloride, and found the patterns created in the quantum spin liquid matched those predicted in an earlier theory.

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