Unconventional superconducter holds promise for quantum computing

Technology News | October 14, 2019

By Rich Pell

Materials & processes Memory & Data Storage MPUs/MCUs Analog Digital Signal Processing IoT

The researchers found that a superconducting material called ß-Bi2Pd contains special properties that they say could be the building blocks for technology of the future. In their study, the researchers found that a ring of ß-Bi2Pd naturally exists between two states in the absence of an external magnetic field – current can inherently circulate both clockwise and counterclockwise, simultaneously, through a ring of ß-Bi2Pd.

This has implications for the qubits used in quantum computing, which not only use two states, but also use a superposition of those two states. A famous example of a qubit, say the researchers, is Schrodinger’s cat, a paradox that posits that a hypothetical cat that may be both dead and alive at the same time (see image).

“A more realistic, tangible implementation of qubit can be a ring made of superconducting material, known as flux qubit, where two states with clockwise- and counterclockwise-flowing electric currents may exist simultaneously,” says Chia-Ling Chien, professor of physics at Johns Hopkins and an author on the paper.

In order to exist between two states, qubits using traditional superconductors require a very precise external magnetic field be applied on each qubit, thus making them difficult to operate in a practical manner.

“A ring of ß-Bi2Pd already exists in the ideal state and doesn’t require any additional modifications to work,” says Yufan Li, a postdoctoral fellow in the Department of Physics & Astronomy at Johns Hopkins University and first author of a paper on the study. “This could be a game changer.”

The next step, say the researchers, is to look for a specific type of particle called Majorana fermions within ß-Bi2Pd. Majorana fermions are particles that are also anti-particles of themselves and are the basis for the development of the next level of disruption-resistant quantum computers—topological quantum computers.

Majorana fermions depend on a special type of superconducting material – a so-called spin-triplet superconductor with two electrons in each pair aligning their spins in a parallel fashion – that has thus far eluded scientists. Through a series of experiments, the researchers found that thin films of ß-Bi2Pd have the special properties necessary for Majorana fermions to exist and are hopeful that the discovery of these special properties will lead to finding Majorana fermions in the material.

“Ultimately, the goal is to find and then manipulate Majorana fermions, which is key to achieving fault-tolerant quantum computing for truly unleashing the power of quantum mechanics,” says Li.

For more, see “Observation of half-quantum flux in the unconventional superconductor ß-Bi2Pd.”