Abstract
The Bell state plays a significant role in the fundamental tests of quantum mechanics, such as the nonlocality of the quantum world. The Bell-state analysis is of vice importance in quantum communication. Existing Bell-state analysis protocols usually focus on the Bell-state encoding in the physical qubit directly. In this paper, we will describe an alternative approach to realize the near complete logic Bell-state analysis for the polarized concatenated Greenberger-Horne-Zeilinger (C-GHZ) state with two logic qubits. We show that the logic Bell-state can be distinguished in two steps with the help of the parity-check measurement (PCM) constructed by the cross-Kerr nonlinearity. This approach can be also used to distinguish arbitrary C-GHZ state with N logic qubits. As both the recent theoretical and experiment work showed that the C-GHZ state has its robust feature in practical noisy environment, this protocol may be useful in future long-distance quantum communication based on the logic-qubit entanglement.
Highlights
The Bell state plays a significant role in the fundamental tests of quantum mechanics, such as the nonlocality of the quantum world
The Bell-state analysis is of vice importance in quantum communication
We show that the logic Bell-state can be distinguished in two steps with the help of the parity-check measurement (PCM) constructed by the cross-Kerr nonlinearity
Summary
The Bell state plays a significant role in the fundamental tests of quantum mechanics, such as the nonlocality of the quantum world. We show that the logic Bell-state can be distinguished in two steps with the help of the parity-check measurement (PCM) constructed by the cross-Kerr nonlinearity. This approach can be used to distinguish arbitrary C-GHZ state with N logic qubits. In 2008, the group of Kwiat beat the channel capacity limit for linear photonic superdense coding[12] They can completely distinguish four polarized Bell states with orbital-angular momentum entanglement. People developed serval approaches to resist the decoherence They presented the quantum repeaters[5] and nonlinear photon amplification[18,19,20] to resist the photon loss during the entanglement distribution. The logic-qubit entanglement, which is called the concatenated GHZ (C-GHZ) state can be described as[38,39,40,41,42]
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