Deterministic Entanglement Purification of the Greenberger-Horne-Zeilinger States in Quantum-Dot and Micro-cavity Coupled System
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An improved purification of the triplet Greenberger-Horne-Zeilinger (GHZ) state is demonstrated for the electron-spin-entangled state in the quantum-dot (QD) and micro-cavity coupled systems. In order to distill the maximally entangled GHZ state efficiently, we designate a deterministic entanglement purification protocol (EPP) by using a pair of the triplet-electron-spin-entangled systems. It is based on the elegant parity-check operations performed in the cavity-spin-coupling system with the assistance of an ancillary single photon. With the current and feasible technology, the maximally entangled GHZ states can be achieved as much as flexible for the long-distance quantum communications since only single-photon detection and single-electron detection are required in practice.
KeywordsEntanglement Quantum purification Greenberger-Horne-Zeilinger state Quantum information
This work was supported by the National Natural Science Foundation of China (61272495, 61379153), the New Century Excellent Talents in University, China (NCET-11-0510), and partly by China Postdoctoral Science Foundation.