Spin-orbit coupling and intrinsic spin mixing in quantum dots

Spin-orbit coupling effects are studied in narrow-gap InSb quantum dots. Competition between different Rashba and Dresselhaus terms is shown to produce wholesale changes in the spectrum. The large (and negative) g factor and the Rashba field produce states where spin is no longer a good quantum number and intrinsic flips occur at moderate magnetic fields. For dots with two electrons, singlet-triplet mixing occurs in the ground state, with observable signatures in intraband far-infrared absorption, and possible importance in quantum computation.