Continuum p-wave Majorana interface mode
= Continuum p-wave Majorana interface mode
{c}
For the long-wavelength Bogoliubov--de Gennes Hamiltonian $H=-\mu(x)\tau_z-i\hbar\Delta\tau_x\partial_x$, a sign change from $\mu>0$ in a one-dimensional p-wave superconductor to $\mu<0$ in the vacuum binds a zero mode of width $\xi=\hbar\Delta/|\mu|$. Neglecting the quadratic kinetic term is valid when $|\mu|\ll m\Delta^2$ up to an inessential numerical factor.