标题： 贝尔对的无歧义制备 显示英文标题

标题： Unambiguous preparation of Bell pairs

摘要： 通过实际方案制备完美的贝尔对在量子通信以及分布式量子计算中具有重要意义。 我们提出一种方案，可以概率性但无歧义地从四个初始处于相同任意纯量子态的量子比特对中生成$\left|\Phi_{+}\right>$贝尔对。 该方案扩展到八个初始处于相同、中等混合量子态的量子比特对时，可以无歧义地生成$\left|\Phi_{+}\right>$贝尔对，并且噪声被二次抑制。 所提方案的核心步骤包括在两个远距离位置分别应用一对局部两量子比特操作，随后在每一方进行部分投影测量和后选择，结果通过经典通信进行传递。 尽管该方案类似于标准的纠缠浓缩协议，但它仅需三次迭代即可成功，使其在现实世界应用中具有吸引力。 显示英文摘要

摘要： The ability of preparing perfect Bell pairs with a practical scheme is of great relevance for quantum communication as well as distributed quantum computing. We propose a scheme which probabilistically, but unambiguously produces the $\left|\Phi_{+}\right>$ Bell pair from four copies of qubit pairs initially in the same arbitrary pure quantum state. The same scheme, extended to eight qubit pairs initially in the same, moderately mixed quantum state, unambiguously produces the $\left|\Phi_{+}\right>$ Bell pair with quadratically suppressed noise. The core step of the proposed scheme consists of a pair of local two-qubit operations applied at each of the two distant locations, followed by a partial projective measurement and postselection at each party, with results communicated classically. While the scheme resembles standard entanglement distillation protocols, it achieves success within just three iterations, making it attractive for real-world applications.