Helical liquid of snake states

We derive an exact solution to the problem of spin snake states induced in a nonhomogeneous magnetic field by a combined action of the Rashba spin-orbit and Zeeman fields. In an antisymmetric magnetic field the spin snake states are nonlocal composite particles, originating from spatially separated entangled spins. Adding an external homogeneous magnetic field breaks the spin-parity symmetry gapping out the spectral branches, which results in a regular beating pattern of the spin current. These new phenomena in a helical liquid of snake states are proposed for an experimental realization.