Efficient purification and concentration for $$\varLambda $$ Λ -type three-level entangled quantum dots using non-reciprocal microresonators

Abstract

Distribution of maximal entanglement is a key technique in long-distance quantum communication. In particular, the entanglement distribution with high fidelity relies on the efficient entanglement purification and concentration. Here in this study, we present a feasible approach to complete the entanglement purification and entanglement concentration for $$\varLambda $$ -type three-level entangled quantum dots by using the whispering-gallery-mode microcavity and the quantum dot coupled system. Exploiting the input–output process of the probe light, we design a parity check gate which allows the quantum non-demolition measurement on the remote entangled quantum dots. Moreover, one can distill a high-fidelity entangled solid-state ensemble from a mixed entangled state or less entangled state ensemble non-locally. The proposed protocol exhibits the advantages of high fidelity which could be further applied to quantum repeaters and quantum information processing with the current experimental technologies.