Spotting the spin of the Majorana fermion under the microscope

Researchers at Princeton University have detected a unique quantum property of an elusive particle notable for behaving simultaneously like matter and antimatter. The particle, known as the Majorana fermion, is prized by researchers for its potential to open the doors to new quantum computing possibilities.

In the study published this week in the journal Science, the research team described how they enhanced an existing imaging technique, called scanning tunneling microscopy, to capture signals from the Majorana particle at both ends of an atomically thin iron wire stretched on the surface of a crystal of lead. Their method involved detecting a distinctive quantum property known as spin, which has been proposed for transmitting quantum information in circuits that contain the Majorana particle.

"The spin property of Majoranas distinguishes them from other types of quasi-particles that emerge in materials," said Ali Yazdani, Princeton's Class of 1909 Professor of Physics. "The experimental detection of this property provides a unique signature of this exotic particle."

The finding builds on the team's 2014 discovery, also published in Science, of the Majorana fermion in a single atom-wide chain of iron atoms atop a lead substrate. In that study, the scanning tunneling microscope was used to visualize Majoranas for the firsttime, but provided no other measurements of their properties.

"Our aim has been to probe some of the specific quantum properties of Majoranas. Such experiments provide not only further confirmation of their existence in ourchains, but open up possible ways of using them." Yazdani said.