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arXiv quant-ph/0310088quant-phhep-th
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超选择规则与量子协议

Superselection rules and quantum protocols

Alexei Kitaev, Dominic Mayers, John Preskill

摘要:

我们表明,超选择规则不增强量子密码协议的信息论安全性。我们的分析采用了两种截然不同的方法。第一种方法使用了参考系的概念--在一个服从超选择规则的世界中,可以由共享访问具有适当属性的参考系的各方来模拟不受限制的操作。通过这种方法,我们证明了,如果一个n方协议是安全的,在世界上的超选择规则,那么安全性保持,即使超选择规则是放松的。然而,证明仅适用于有限的一类超选择规则,其中超选择扇区被标记为一个紧凑的对称群的酉不可约表示。第二种方法使用在各方之间发送的消息的格式的概念--通过验证格式,消息的接收者可以检查消息是否可能是由执行了费用节省操作的一方发送的。通过这种方法,我们证明了一般的超选择规则(包括那些有关的nonabelian任意子在两个维度)的协议是没有更安全的协议在无限制的世界。然而,该证明仅适用于两方协议。我们的研究结果特别表明,如果不对作弊者的计算能力进行假设,那么在一个受超选择规则约束的世界中,安全的量子比特承诺和具有任意小偏差的强量子硬币翻转是不可能的。

英文摘要:

We show that superselection rules do not enhance the information-theoretic security of quantum cryptographic protocols. Our analysis employs two quite different methods. The first method uses the concept of a reference system -- in a world subject to a superselection rule, unrestricted operations can be simulated by parties who share access to a reference system with suitable properties. By this method, we prove that if an n-party protocol is secure in a world subject to a superselection rule, then the security is maintained even if the superselection rule is relaxed. However, the proof applies only to a limited class of superselection rules, those in which the superselection sectors are labeled by unitary irreducible representations of a compact symmetry group. The second method uses the concept of the format of a message sent between parties -- by verifying the format, the recipient of a message can check whether the message could have been sent by a party who performed charge-conserving operations. By this method, we prove that protocols subject to general superselection rules (including those pertaining to nonabelian anyons in two dimensions) are no more secure than protocols in the unrestricted world. However, the proof applies only to two-party protocols. Our results show in particular that, if no assumptions are made about the computational power of the cheater, then secure quantum bit commitment and strong quantum coin flipping with arbitrarily small bias are impossible in a world subject to superselection rules.

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。

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