Robust photonic entanglement distribution by state-independent encoding onto decoherence-free subspace

Abstract

Efficient and faithful implementation of quantum information tasks, e.g., quantum computing, quantum communication and quantum metrology [1,2,3], requires robust and state-independent decoherence-suppressing measures to protect quantum information carriers. Here we present an experimental demonstration of a robust distribution scheme in which one photon of an entangled photon pair is successfully encoded into and decoded from a decoherence-free subspace (DFS) by a state-independent scheme. We achieved a high-fidelity distribution of the entangled state over fibre communication channel, and also demonstrated that the scheme is robust against fragility of the reference frame. The scheme, thanks to its state-independence, is also applicable to multipartite case where the photon to be distributed is entangled with many other photons. Such a universal scheme opens the possibility of robust distribution of quantum information among quantum communication and computing networks.Encoding into a decoherence-free subspace (DFS)[4] is one of the effective schemes to protect quantum states against decoherence by exploiting symmetries in system-environment interactions. Let us briefly introduce the robustness of quantum states in a simple example of DFS. Consider a quantum channel that adds a random phase shift ϕ S , transforming |0 S → |0 S and |1 S → e iϕ S |1 S , where |0 S and |1 S are orthogonal states of qubit S. If the

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Creation of high-quality long-distance entanglement with flexible resources

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Fault tolerant quantum secret sharing against collective-amplitude-damping noise

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