A particle can be its own anti-particle – this was the phenomenal insight of the mysterious physics genius Ettiore Majorana, who went missing in 1938 and was never found. These particles have been widely searched for and has generated considerable amount of interest in the theoretical physics community, but have not been found. Now, the LHC has been quite actively searching for signatures of these particles.
Condensed Matter physicists join in…
Interestingly, and very importantly, a lot of modern day condensed matter research focusses on the type of signatures that Majorana particles can produce and how they can be detected. It is in this context that wonderful news comes in from a team of Dutch researchers, who have reported seeing signatures for these particles.
Device and Methodology
The team has been fabricated a device which comprises a nanowire forming a junction between a semiconductor and a superconductor. The team then applied a magnetic field parallel to the nanowire and this restricts electrons to only certain energies, creating so-called ‘band gaps’. Electrons can reside only in these band gaps.
The team then measured the conductivity of the material given different gate voltages and found that there are two small peaks in the conductances placed symmetrically about the zero bias voltage. Scientists think that these peaks are due to particles and anti-particles respectively, but they are just the same, i.e. they are Majorana fermions.
The team varied the magnetic field and the bias voltage over large ranges of values, but they dips stayed constant. All of this leads the team to conclude that the charge carriers in nanowire were indeed Majorana fermions.
The work appears here: http://www.sciencemag.org/content/early/2012/04/11/science.1222360.full.pdf