Electrically tunable entanglement of an interacting electron pair in a spin-active double quantum dot

Abstract

Finding efficient methods for controlling entanglement is an important issue in quantum information processing. Here, we inspect theoretically possible ways for tuning orbital and spin entanglement of two interacting particles confined to a double quantum dot with spin-orbit coupling (SOC) which renders possible the coupling of spin to an external electric field. The entanglement in the spin part is sensitive to a transverse electric field. We show that through the field-induced SOC the entanglement of the spin subsystem can be slightly increased; the effect of a longitudinal electric field is more subtle: For a small interdot distance, a longitudinal electric field enhances substantially the entanglement of spins, while for a large interdot distance it has no impact. An external longitudinal electric field has a minor effect on the entanglement in the orbital part irrespective of the interdot distance. We trace back this observed phenomenon to a combined effect of the applied external electric field and the overlap of wave functions which is enhanced for decreasing interdot distances. As a result, at large interdot separation, the concurrence of the two-electron states turns insensitive to the applied electric field.