Bangladeshi ends 85-year wait for massless particle
Eighty five years after Hermann Weyl, a physicist and mathematician, proposed Weyl fermions, a massless particle that also carried an electric charge, a team of scientists led by a Bangladeshi has found its existence.
The team at the Princeton University in the USA, led by Zahid Hasan, made the groundbreaking discovery while the journal Science published the results of their research in detail on 16 July.
In a telephone conversation with the Prothom Alo, Zahid told this correspondent that this discovery will usher in a new era of electronics where the main features will be speedy and accurate.
When asked how different the devices in the new era will be, Zahid said, “For an example, the mobile phones made using this technology will be less susceptible to heat after longer use. Because, this particle has no mass and it does not wander around like electrons.”
“A Weyl semimetal is a crystal which hosts Weyl fermions as emergent quasiparticles and admits a topological classification that protects Fermi arc surface states on the boundary of a bulk sample. This unusual electronic structure has deep analogies with particle physics and leads to unique topological properties,” Zahid’s team said in the abstract of the paper.
“We report the experimental discovery of a Weyl semimetal, TaAs. Using photoemission spectroscopy, we directly observe Fermi arcs on the surface, as well as the Weyl fermion cones and Weyl nodes in the bulk of TaAs single crystals. We find that Fermi arcs terminate on the Weyl nodes, consistent with their topological character. Our work opens the field for the experimental study of Weyl fermions in physics and materials science,” it added.
“For years, scientists thought neutrinos were Weyl fermions. However, in 1998, physicists discovered neutrinos do have mass and the hunt for Weyl fermions began,” Zahid said.
“These results are very exciting for me personally, since I've been involved significantly in the theoretical discovery of Weyl semimetals a few years ago,” said physicist Anton Burkov at the University of Waterloo in an interview of international journal IEEE Spectrum. “It’s very exciting to finally see them discovered experimentally in real materials.”
The team of researchers led by physicist Zahid Hasan has detected Weyl fermions within in large crystals and also observed that the fermions can only exist within the crystals.
However, Zahid thinks they might have to wait around 10 to 20 years for the new era electronics.
Graphene has already received vast popularity as an element of new era electronics. People have been producing transistor, optical photo sensor and nanosensor using graphene for a long time. But producing graphene is a troublesome task.
The Nobel Prize in Physics 2010 was awarded jointly to Andre Geim and Konstantin Novoselov for the invention of graphene.
Prof Arshad Momen, chairman of Dhaka University’s Theoretical Physics department told Prothom Alo, “Weyl semimetal could be used for serving those purposes which are being done by graphene. But, graphene is tough to be produced as it is two-dimensional. In comparison to graphene, Weyl fermion is easy to be produced and changed as it is three-dimensional.”
“It looks more attracting for me to hear the existence of Weyl fermion rather than its usages. Echoing Einstein, I can say God has used a wonderful mathematical concept in nature,” Arshad Momen added.
Zahid Hasan is the eldest son of lawyer father Rahmat Ali and housewife mother Nadira Begum. He has a younger brother and daughter. He passed his SSC from Dhanmondi Government Boys' High School and HSC from Dhaka College with great results.
Zahid studied at Texas University in Austin, USA where he worked under Nobel laureate Steven Weinberg.
Steven inspired Zahid to work on experiment-based physics. Later, he started working at Princeton University as a physics teacher.
He is now a professor of physics at Princeton University.
Zahid received worldwide acclaim last year for his discovery of topological insulator.