Quantum computing utilizes 3D crystals

By WILLIAM XIE | May 4, 2017


2D liquid crystals are commonly used in smart phone and television display screens.

Researchers at the Institute for Quantum Information and Matter at the California Institute of Technology (Caltech) recently discovered a new state of matter, the 3D quantum liquid crystal.

“We have detected the existence of a fundamentally new state of matter that can be regarded as a quantum analog of a liquid crystal,” David Hsieh, assistant professor of physics at Caltech, said in a press release.

Liquid crystals flow like a liquid but are structurally oriented like a solid. Quantum liquid crystals contain electrons that act nematic, or arrange themselves in a parallel manner.

Quantum liquid crystals are not a foreign concept.  2D quantum liquid crystals were first discovered in 1999 by a Caltech professor. As the name suggests, 2D quantum liquid crystals flow in a flat plane, moving in one particular direction. 2D quantum crystals can also be found in high-temperature superconductors.

“Electrons living in this flatland collectively decide to flow preferentially along the x-axis rather than the y-axis even though there’s nothing to distinguish one direction from the other,” John Harter, a postdoctoral researcher at the Caltech lab, said in a press release.

3D quantum crystals have more states. They can move along three axes, in a forward or backward motion. If a current is run through the material, the motion of the electrons yields a different magnetic strength and magnetic orientation.

The 3D quantum liquid crystal was found, surprisingly, in the metallic pyrochlore Cd2Re2O7 using second harmonic optical anisotropy measurements. In fact, researchers were originally interested in studying the atomic structure of Cd2Re2O7 using second harmonic optical anisotropy and encountered results inexplicable using solely the concept of a 2D quantum liquid crystal.

Like liquid crystals, the new phase spontaneously breaks rotational symmetry.  Their paper, which was published in Science, described how the researchers found that there was a spin-orbit coupling which suggested that the material had a 3D quantum nature.

According to Science Daily, Harter was at first surprised by their findings and questioned their results. They were able to connect the dots when they accounted for the concept of 3D quantum liquid crystals, which was developed by Liang Fu, a physics professor at the Massachusetts Institute of Technology.

Liquid crystals can be found in nature but they can also be created artificially. Liquid crystal displays are commonly found in smartphones, televisions and other display screens.

The researchers question whether the 3D quantum liquid crystals could be implemented in a computer chip.

The nature of the electrons in the 3D quantum liquid crystals may be suitable for advancement in quantum computing, which uses quantum states to increase operating speed. Researchers’ theoretical models show that 3D quantum liquid crystals can have topological superconducting phases.

“3D quantum liquid crystals could be the precursors to topological superconductors we’ve been looking for,” said Hsieh in a press release.

Topological superconductors can stabilize the uncertain nature of quantum computing. Creating topological superconductors using the 3D quantum liquid crystals can open a new field in quantum computing.

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