arXiv quant-ph/00060452000-06-09quant-ph

量子比特的最佳操纵：通用量子纠缠

Optimal manipulations with qubits: Universal quantum entanglers

Vladimir Buzek, Mark Hillery

备注：: 11 pages, 3 eps figures, accepted for publication in Phys. Rev. A
发表信息：: Phys. Rev. A 62 (2000) 022303
DOI：: 10.1103/PhysRevA.62.022303

摘要：

我们分析了纠缠两个最初未纠缠的量子比特的各种情况。特别地，我们提出了一个最优的通用纠缠器，它使处于未知态$|Ψ>$的量子比特与处于参考（已知）态$|0>$的量子比特纠缠。也就是说，我们的纠缠器产生的输出态尽可能接近纯（对称化）态$(|Ψ>|0> +|0>|Ψ>)$。这种纠缠机最吸引人的特点是其性能的保真度（即输出与理想纠缠对称态之间的距离）不依赖于输入，并且取恒定值$F= (9+3\sqrt{2})/14\simeq 0.946$。我们还分析了如何最佳地从一个量子比特初始准备在一个未知的状态$|Ψ\r$的两个量子比特纠缠系统，这是尽可能接近贝尔态$(|Ψ\r|Ψ^\perp\r+|Ψ^\perp\r|Ψ\r)$，其中$łΨ|Ψ^\perp\r =0$。

英文摘要：

We analyze various scenarios for entangling two initially unentangled qubits. In particular, we propose an optimal universal entangler which entangles a qubit in unknown state $|Ψ>$ with a qubit in a reference (known) state $|0>$. That is, our entangler generates the output state which is as close as possible to the pure (symmetrized) state $(|Ψ>|0> +|0>|Ψ>)$. 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 $F= (9+3\sqrt{2})/14\simeq 0.946$. We also analyze how to optimally generate from a single qubit initially prepared in an unknown state $|Ψ\r$ a two qubit entangled system which is as close as possible to a Bell state $(|Ψ\r|Ψ^\perp\r+|Ψ^\perp\r|Ψ\r)$, where $łΨ|Ψ^\perp\r =0$.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

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