2000/06/09 by Vladimír Bužek, Vladimir Buzek, Mark Hillery · 1 citation
Computer Science · Mathematics · Physics and Astronomy · #Algorithm #Cluster state #Combinatorics #Computer science #Constant (computer programming) #Fidelity #Mathematics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum mechanics #Qubit #State (computer science) #Statistics #Telecommunications #Topology (electrical circuits) #Value (mathematics) #W state #quant-ph
paper · pdf · doi:10.1103/physreva.62.022303
published as Phys. Rev. A 62 (2000) 022303 · 11 pages, 3 eps figures, accepted for publication in Phys. Rev. A
arxiv created 2000/06/09 · openalex publication_date 2000/07/12 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We analyze various scenarios for entangling two initially unentangled qubits. In particular, we propose an optimal universal entangler that entangles a qubit in unknown state |\ensuremathΨ〉 with a qubit in a reference (known) state |0〉. That is, our entangler generates the output state that is as close as possible to the pure (symmetrized) state (|\ensuremathΨ〉|0〉+|0〉|\ensuremathΨ〉). The most attractive feature of this entangling machine, is that the fidelity of its performance (i.e., the distance between the output and the ideally entangled---symmetrized state) does not depend on the input and takes the constant value F=(9+3√(2))/14\ensuremath≃0.946. We also analyze how to optimally generate from a single qubit initially prepared in an unknown state |\ensuremathΨ〉 a two qubit entangled system, which is as close as possible to a Bell state (|\ensuremathΨ〉|\ensuremathΨ^\ensuremath⊥〉+|\ensuremathΨ^\ensuremath⊥〉|\ensuremathΨ〉), where 〈\ensuremathΨ|\ensuremathΨ^\ensuremath⊥〉=0.