Quantum Network Coding
Quantum Network Coding
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DOI：
10.1007/978-3-540-70918-3_52
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发表时间：
2006-01
期刊：
影响因子：
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通讯作者：
Masahito Hayashi;K. Iwama;H. Nishimura;Raymond H. Putra;S. Yamashita
中科院分区：
文献类型：
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作者：
Masahito Hayashi;K. Iwama;H. Nishimura;Raymond H. Putra;S. Yamashita
由于量子信息是连续的，它的处理有时比经典的对应物更难。一个典型的例子是克隆;复制数字信息是简单的，但对于量子信息来说是不可能的。本文的问题是量子网络编码是否可能。它的经典对应物是另一个很好的例子，表明数字信息流可以做得更有效地比传统的（比如，液体）flow. We的答案是类似的克隆的情况下，即，它表明，量子网络编码是可能的，如果允许近似，通过使用一个简单的网络模型称为蝴蝶。在该网络中，有两条流路径s1 tot 1和s2 tot 2，它们共享一个容量为1的瓶颈通道。在经典的情况下，我们可以同时发送两个比特，每个路径一个，尽管有瓶颈。我们的量子网络编码结果包括：（i）我们可以发送任何量子态从1 tot 1和从2 tot 2同时与保真度严格大于1/2。(ii)如果其中一个是经典的，那么保真度可以提高到2/3。(iii)类似的改进也是可能的，如果和仅限于有限数量的（先前已知的）状态。(iv)给出了几个不可能结果，包括保真度的一般上界。
Since quantum information is continuous, its handling is sometimes surprisingly harder than the classical counterpart. A typical example is cloning; making a copy of digital information is straightforward but it is not possible exactly for quantum information. The question in this paper is whether or notquantumnetwork coding is possible. Its classical counterpart is another good example to show that digital information flow can be done much more efficiently than conventional (say, liquid) flow.Our answer to the question is similar to the case of cloning, namely, it is shown that quantum network coding is possible if approximation is allowed, by using a simple network model called Butterfly. In this network, there are two flow paths,s1tot1ands2tot2, which shares a single bottleneck channel of capacity one. In the classical case, we can send two bits simultaneously, one for each path, in spite of the bottleneck. Our results for quantum network coding include: (i) We can send any quantum statefroms1tot1andfroms2tot2simultaneously with a fidelity strictly greater than 1/2. (ii) If one ofandis classical, then the fidelity can be improved to 2/3. (iii) Similar improvement is also possible ifandare restricted to only a finite number of (previously known) states. (iv) Several impossibility results including the general upper bound of the fidelity are also given.