Entanglement between spin and orbital degrees of freedom in a 2D electron gas
The Rashba interaction couples spin and orbital degrees of freedom in a two-dimensional electron gas. A Landau level basis leads to an equivalent spin-boson model that couples adjacent Landau levels. We study the entanglement between the spin and orbital subspaces in the ground state of a gas of electrons described by this Hamiltonian. The spin-orbit entanglement entropy as a function of filling factor is piecewise smooth with discontinuous derivatives due to gapped levels of degenerate orbitals and level crossings.