Electromagnetic absorption of quasi‐1D Majorana nanowires

Abstract

We calculate the electromagnetic absorption cross section of long and narrow nanowires, in the so-called quasi-1D limit. We consider only two transverse bands and compute the dipole absorption cross section taking into account quasiparticle transitions from negative to positive energy eigenstates of the Bogoliubov-de Gennes Hamiltonian. The presence of the zero energy (Majorana) state manifests in the different absorption spectra for x (parallel) and y (transverse) polarizations of the electromagnetic field.In the y-polarized case, the Majorana state causes a low energy absorption plateau extending from mid-gap up to full-gap energy. Increasing further the energy, the plateau is followed by a region of enhanced absorption due to transitions across the full gap. For x polarization the low energy absorption plateau is not observed.

Complex band-structure analysis and topological physics of Majorana nanowires

“…The first one starts at half the energy gap while the second starts at the energy of the full gap. The two-plateau behaviour is obtained only in presence of Majoranas and with y-polarized light; x-polarized light does not allow to clearly distinguish the two absorption plateaus [73,74].…”

“…This section discusses calculations of the optical absorption of a 2D-q1D nanowire in longitudinal magnetic field [73,74], with the Hamiltonian of Eq. (14) of Sec.…”

Circular dichroism of chiral Majorana states

“…We want to investigate how this behavior is actually realized by explicit calculations of the optical aborption. In previous works we analyzed the optical absorption of localized Majorana states in nanowires [ 25 – 26 ]. In those systems the CD vanishes and the presence of the Majorana state is signaled by a plateau with lower absorption, starting at mid-gap energy, of the y -polarized signal with respect to the x -polarized signal.…”

Circular dichroism of chiral Majoranas

“…We want to investigate how this behavior is actually realized by explicit calculations of the optical aborption. In previous works we analyzed the optical absorption of localized Majoranas in nanowires [24,25]. In those systems the CD vanishes and the presence of the Majorana is signaled by a lower-absorption plateau, starting at mid-gap energy, of the y-polarized signal with respect ot the x-polarized one.…”