On quantum fidelities and channel capacities
On quantum fidelities and channel capacities
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DOI：
10.1109/18.850671
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发表时间：
2000-07-01
影响因子：
2.5
通讯作者：
Nielsen, MA
中科院分区：
文献类型：
--
作者：
Barnum, H;Knill, E;Nielsen, MA
对于离散无记忆量子信道，我展示了量子信道容量的两种不同概念的等价性：一种是使用纠缠保真度作为传输成功的标准，另一种是使用输入希尔伯特空间子空间中纯态的最小保真度作为其标准。因此，熵率小于容量的火炮源可以以高的纠缠保真度传输。我们还证明了一类有限的编码足以传输任何可能在给定信道上传输的量子源。这使我们能够简化信道容量的已知上界，也使我们能够证明从编码器到解码器的辅助经典信道的可用性不会增加量子容量。
For the discrete memoryless quantum channel, me show the equivalence of two different notions of quantum channel capacity: that which uses the entanglement fidelity as its criterion for success in transmission, and that which uses the minimum fidelity of pure states in a subspace of the input Hilbert space as its criterion. As a corollary, arty source with entropy rate less than the capacity may be transmitted with high entanglement fidelity. We also show that a restricted class of encodings is sufficient to transmit any quantum source which may be transmitted on a given channel. This enables us to simplify a known upper bound for the channel capacity It also enables us to show that the availability of an auxiliary classical channel from encoder to decoder does not increase the quantum capacity.