We present an efficient entanglement concentration protocol (ECP) for electron spins based on quantum-dot and microcavity coupled systems. In our ECP, each two-electron spin system in a partially entangled state can be concentrated with the assistance of an ancillary quantum dot and a single photon, not two copies of two-electron spin systems. With current and near-future technology, the locally maximal entanglement of electron spins can be achieved, and our ECP can be used in long-distance quantum communications.

• Received 29 March 2012

DOI:https://doi.org/10.1103/PhysRevA.86.012323