Majorana particles, which were predicted 80 years ago by Italian theoretical physicist Ettore Majorana, could become critical building blocks for quantum computers because of their unusual properties which make them resistant to external interference and prevent loss of quantum information.
"The discovery could make it possible to control Majorana fermions and realise robust topological quantum computing," explained Dr. Joe Qiu, manager of the Solid-State Electronics Program within the Engineering Sciences Directorate at the Army Research Office, an element of the U.S. Army Research Laboratory, located at Research Triangle Park in Durham, North Carolina.
Quantum computers are quicker and more efficient than classical computers and could, potentially, lead to significant improvements in situational awareness with the capability to process large amount of available data.
"Prior experimental approaches based on semiconductor nanowires on superconductors have produced inconclusive signals which could also be attributed to other effects," Qiu said. "This experiment using stacked layers of magnetic topological insulator and superconductor has demonstrated the clearest and most unambiguous evidence of the particles as predicted by theory so far."
The research is a result of collaboration between a team of researchers including electrical engineers, physicists and material scientists and was led by Prof. Kang Wang, a UCLA distinguished professor of electrical engineering, of physics and of materials science and engineering, who also holds UCLA's Raytheon Chair in Electrical Engineering.
"Because the Majorana particle is its own anti-particle, carrying zero electrical charge, it is viewed as the best candidate to carry a quantum bit, or qubit, the unit of data that would be the foundation of quantum computers. Unlike 'bits' of data in standard computers, which can be represented as either 0s or 1s, qubits have the ability to be both 0s and 1s, a property that would give quantum computers exponentially more computing power and speed than today's best supercomputers," Qiu said.
The Majorana particle has been the focus of research for quantum computing because its neutral charge makes it resistant to external interference and gives it the ability to leverage and sustain a quantum property known as entanglement. Entanglement allows two physically separate particles to concurrently encode information, which could generate enormous computing power.
For their research, the team set up a superconductor, a material that allows electrons to flow freely across its surfaces without resistance, and placed above it a thin film of a new quantum material called topological insulator, to give the engineers the ability to manipulate the particles into a specific pattern. After sweeping a very small magnetic field over the setup, the researchers found the Majorana particles' distinct quantized signal in the electrical traffic between the two materials.
In the experiment, Majorana particles travelled along the topological insulator's edges in a distinct braid-like pattern.
The researchers said the next step in their research will be to explore how to use Majorana particles in quantum braiding, which would knit them together to allow information to be stored and processed at super high speeds.