Spin entanglement induced by spin-orbit interactions in coupled quantum dots

Abstract

We theoretically explore the possibility of creating spin quantum entanglement in a system of two electrons confined respectively in two vertically coupled quantum dots in the presence of Rashba-type spin-orbit coupling. We find that the system can be described by a generalized Jaynes-Cummings model of two-mode bosons interacting with two spins. The lower excited states of this model are calculated to reveal the underlying physics of the far-infrared absorption spectra. The analytic perturbation approach shows that an effective transverse coupling of spins can be obtained by eliminating the orbital degrees of freedom in the large-detuning limit. Here, the orbital degrees of freedom of the two electrons, which are described by two-mode bosons, serve as a quantized data bus to exchange the quantum information between the two electron spins. Then a nontrivial two-qubit logic gate is realized and spin entanglement between the two electrons is created by virtue of spin-orbit interactions.