Probability current of a two-dimensional Dirac particle
= Probability current of a two-dimensional Dirac particle
{c}
{title2=$\mathbf j=c\Psi^\dagger(\sigma_x,\sigma_y)\Psi$}
For a Hermitian local mass coefficient and $H=c\boldsymbol\sigma\cdot\mathbf p+V\sigma_z$, the density and current obey $\partial_t(\Psi^\dagger\Psi)+\nabla\cdot(c\Psi^\dagger\boldsymbol\sigma\Psi)=0$. A normalized $\sigma_x=-1$ interface <spinor> carries $j_x=-c\rho$ and $j_y=0$.