Title: Optical responses of chiral Majorana modes
Speaker: He Jun (Institute of Physical and Chemical Research，Japan)
Time: January 4, 15:00
Venue: Room 220, Building 18, Wushan Campus
Majorana fermions exist on the boundaries of two-dimensional topological superconductors (TSCs) as charge-neutral quasiparticles. The neutrality makes the detection of such states challenging from both experimental and theoretical points of view. Current methods largely rely on transport measurements in which Majorana fermions manifest themselves by inducing electron-pair tunneling (Andreev reflection) at the lead-contacting point. In this talk, I will discuss alternative detecting methods --- by shining light.
I will show that chiral Majorana fermions in TSCs generate local optical responses. This results in a local optical conductivity σxx that is proportional to ω2 when the photon frequency ω is small . The features of the σxx distinguish chiral Majorana fermions not only from trivial superconductors or insulators (where σxx=0), but also from normal fermion edge states such as those in quantum Hall systems (where σxx=e2/2h). Then we further discuss the optical responses of chiral Majorana modes in Kitaev model of quantum spin liquids (QSLs), where the optical signal can be detected locally by Raman spectroscopy  since the Raman scattering intensity is proportional to ω3, where ω is the Raman frequency shift.
Announced by the School of Physics and Optoelectronics