Purification of the concatenated Greenberger–Horne–Zeilinger state with linear optics

Abstract

Logic qubit plays an important role in quantum computation. Recent research showed that logic qubit entanglement can be used in long-distance quantum communication. In this paper, we describe an entanglement purification protocol (EPP) for one type of logic qubit entanglement, named concatenated Greenberger–Horne–Zeilinger(C-GHZ) state. Not only the logic bit-flip and phase-flip errors in the C-GHZ state but also the single physical qubit bit-flip and phase-flip errors in the logic qubit can be purified. This EPP does not require the sophisticated controlled-not gate, but only requires some feasible linear optical elements, which is feasible in the current experimental condition.