Events in Physics
Professor Tapash Chakraborty, University of Manitoba, Canada
Physics Departmental Colloquium
Title: "Elusive Tachyons in topological insulators"
By: Professor Tapash Chakraborty
Universiteit Antwerpen, Belgium (sabbatical leave) and University of Manitoba, Canada (permanent address)
Date: Wednesday 24th October
Time: 16.30pm
Place: PLT
Abstract: In this talk, I shall discuss some unique properties of the surface states at the junction of two topological insulators. We discovered that these states, under certain conditions exhibit superluminal (tachyonic) dispersion of Dirac fermions. Tachyons have eluded detection until now, despite diligent efforts by particle physicists worldwide. Tachyons have remained a mystery for over five decades. Not much is known about their physical properties, as they were generally defined as `hypothetical particles that have never been found in nature'.
Although superluminal excitations are known to exist in optical systems, this is the first demonstration of possible tachyonic excitations in a purely electronic system. The first ever signature of tachyons could therefore be found experimentally in a topological insulator junction. It would indeed be a remarkable feat for condensed matter and materials sciences if the first ever signature of elusive tachyons is actually detected experimentally in a topological insulator junction. In the presence of an external magnetic field, the Landau levels, evaluated from an effective two-dimensional model for tachyons, and from the junction states of two topological insulators, show some unique properties not seen in conventional electrons systems or in a single TI [1]. The techniques to explore these have been developed by many experimental groups in the past, in graphene or in a single topological insulator. Experimental confirmation of these unusual magnetic properties will help confirm the presence of tachyons in the system.