Optical implementation of entangled multi-spin states in a CdTe quantum well

Ultrafast optical pulses and coherent techniques are used to create spin entangled states of non-interacting electrons bound to donors in a CdTe quantum well. Our method, relying on the exchange interaction between optically excited holes and the impurities, can in principle, be applied to entangle a large number of spins. Results are presented for resonant excitation of localized excitons below the gap, and above the gap where the signatures of entanglement are significantly enhanced.