JUL 28, 2017 1:00 PM PDT

The Confirmed Discovery of Majorana Fermion

WRITTEN BY: Daniel Duan

In a recent publication in the prestigious journal Science, a joint research team comprised of physicists from Stanford, UC Irvine and UCLA announced that they had confirmed the existence of Majorana fermion.

It is impossible to understand their claim and the implication of their discovery without digging through some of the most intriguing chapters in the history of physics. In the standard model, each fermion (such as proton, neutron, electron, neutrino, and quark) particle has its antiparticle. The two are mirrored images, share the same mass, but have opposite electric charge. This idea was first put forward by physicist Paul Dirac, as a deduction from his name sake equation that describes the wave function of electrons. In 1932 the observation of positron, the antiparticle of electron, verified the matter-antimatter theory. Like many good dramas in life, physicist Ettore Majorana added a new twist to the idea. In 1937, he predicted that among the fermions there should be a class of particles that are their own antiparticles, and they are thus named Majorana fermions.

Ettore Majorana. Credit: Wikipedia

Related: the Standard Model of Physics

The original prediction applied only to fermions that have no charge such as neutrino. Scientists have long suspected neutrino is a Majorana fermion. Currently, there are four experiments underway to find out if the neutrino is indeed its own antiparticle. The EXO-200 at the Enriched Xenon Observatory in New Mexico is one of them. Because these experiments are extraordinarily difficult, no definitive conclusion will be reached anytime soon.

Though some continue to seek out the elementary Majorana particle, others propose that the observation of Majorana particle-like behavior in quasiparticles is the next closest thing. (In the field of condensed matter physics, a quasiparticle is a quantum of energy in a system of many bodies that behave like one single particle.) In another word, instead of looking for one particle, why not create a quasiparticle that bears the signature of Majorana fermions?

Majorana quasiparticles observed in superconducting topological insulator. Majorana fermions (red, and purple) travel through a topological insulator. Electrons (green) travel on the edges of the topological insulator. Credit: Beijing Sondii Technology Co Ltd

This is the angle the team of US scientists approaches the problem. To observe Majorana Fermion-like quasiparticles, they first created a superconducting topological insulator by coupling a thin film insulator with a layer of superconductor. On this device, electrons can travel along two edges of the insulator without resistance. Then the researchers swept a magnet over the insulator, which slowed down, stopped and switched the direction of the flow of electrons abruptly. During cycles of this modulated movement, Majorana quasiparticles emerged in pairs and traveling through the insulator. While one member of each pair got deflected out of the path, the other continued forward. Like the electrons, they slowed down, stopped and changed direction under the influence of the magnet. But unlike the electrons, their movement bore the signature of Majorana fermion - the half-integer quantized conductance plateaus.

The team of scientists called their quasiparticles as “Angel Particle,” quoting the matter-antimatter explosive appearing in the Dan Brown’s thriller Angels and Demons. Since Majorana fermions are their own antiparticles, therefore they are only angels - no demons.

Dr. Shoucheng Zhang, a theoretical physicist and one of the senior authors, expressed his excitement over the findings: “Our team predicted exactly where to find the Majorana fermion and what to look for as its ‘smoking gun’ experimental signature. This discovery concludes one of the most intensive searches in fundamental physics, which spanned exactly 80 years.”

Source: Stanford University/Science

About the Author
  • Graduated with a bachelor degree in Pharmaceutical Science and a master degree in neuropharmacology, Daniel is a radiopharmaceutical and radiobiology expert based in Ottawa, Canada. With years of experience in biomedical R&D, Daniel is very into writing. He is constantly fascinated by what's happening in the world of science. He hopes to capture the public's interest and promote scientific literacy with his trending news articles. The recurring topics in his Chemistry & Physics trending news section include alternative energy, material science, theoretical physics, medical imaging, and green chemistry.
You May Also Like
AUG 14, 2020
Chemistry & Physics
Cosmic Rays Might Have Played a Role in Shaping Our Genetic Materials
AUG 14, 2020
Cosmic Rays Might Have Played a Role in Shaping Our Genetic Materials
DNA, whose signature double helix structure scored Watson and Crick (and Frankland presumably according to many) a Nobel ...
SEP 12, 2020
Chemistry & Physics
Colorimetric sensor detects presence of airborne pathogens
SEP 12, 2020
Colorimetric sensor detects presence of airborne pathogens
The development of a novel colorimetric sensor may bring some mental relief to your COVID-19 anxieties. According to the ...
OCT 09, 2020
Chemistry & Physics
COVID-19 transmitted in a fractal nature
OCT 09, 2020
COVID-19 transmitted in a fractal nature
New research published under the title “Fractal signatures of the COVID-19 spread” in the journal Chaos ...
OCT 26, 2020
Chemistry & Physics
Fighting mesothelioma with gold nanotubes
OCT 26, 2020
Fighting mesothelioma with gold nanotubes
New research published in the journal Small details how gold nanotubes could be used to treat mesothelioma cancer. ...
NOV 20, 2020
Chemistry & Physics
The Passing of a Neutrino Hunting Pioneer
NOV 20, 2020
The Passing of a Neutrino Hunting Pioneer
Masatoshi Koshiba, a revered Japanese physicist known for his groundbreaking work on cosmic neutrino detection, passed a ...
NOV 15, 2020
Chemistry & Physics
Chemical reactivity flowcharts assist chemists in interpreting reaction outcomes
NOV 15, 2020
Chemical reactivity flowcharts assist chemists in interpreting reaction outcomes
New research published in Organic Letters from Purdue University scientists presents the design and development of ...
Loading Comments...