dorsal/arxiv
View SchemaQuantum Network Coding for General Graphs
| Authors | Kazuo Iwama, Harumichi Nishimura, Rudy Raymond, Shigeru Yamashita |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0611039 |
| URL | https://arxiv.org/abs/quant-ph/0611039 |
Abstract
Network coding is often explained by using a small network model called Butterfly. In this network, there are two flow paths, s_1 to t_1 and s_2 to t_2, which share a single bottleneck channel of capacity one. So, if we consider conventional flow (of liquid, for instance), then the total amount of flow must be at most one in total, say 1/2 for each path. However, if we consider information flow, then we can send two bits (one for each path) at the same time by exploiting two side links, which are of no use for the liquid-type flow, and encoding/decoding operations at each node. This is known as network coding and has been quite popular since its introduction by Ahlswede, Cai, Li and Yeung in 2000. In QIP 2006, Hayashi et al showed that quantum network coding is possible for Butterfly, namely we can send two qubits simultaneously with keeping their fidelity strictly greater than 1/2. In this paper, we show that the result can be extended to a large class of general graphs by using a completely different approach. The underlying technique is a new cloning method called entanglement-free cloning which does not produce any entanglement at all. This seems interesting on its own and to show its possibility is an even more important purpose of this paper. Combining this new cloning with approximation of general quantum states by a small number of fixed ones, we can design a quantum network coding protocol which ``simulates'' its classical counterpart for the same graph.
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"abstract": "Network coding is often explained by using a small network model called\nButterfly. In this network, there are two flow paths, s_1 to t_1 and s_2 to\nt_2, which share a single bottleneck channel of capacity one. So, if we\nconsider conventional flow (of liquid, for instance), then the total amount of\nflow must be at most one in total, say 1/2 for each path. However, if we\nconsider information flow, then we can send two bits (one for each path) at the\nsame time by exploiting two side links, which are of no use for the liquid-type\nflow, and encoding/decoding operations at each node. This is known as network\ncoding and has been quite popular since its introduction by Ahlswede, Cai, Li\nand Yeung in 2000. In QIP 2006, Hayashi et al showed that quantum network\ncoding is possible for Butterfly, namely we can send two qubits simultaneously\nwith keeping their fidelity strictly greater than 1/2.\n In this paper, we show that the result can be extended to a large class of\ngeneral graphs by using a completely different approach. The underlying\ntechnique is a new cloning method called entanglement-free cloning which does\nnot produce any entanglement at all. This seems interesting on its own and to\nshow its possibility is an even more important purpose of this paper. Combining\nthis new cloning with approximation of general quantum states by a small number\nof fixed ones, we can design a quantum network coding protocol which\n``simulates\u0027\u0027 its classical counterpart for the same graph.",
"arxiv_id": "quant-ph/0611039",
"authors": [
"Kazuo Iwama",
"Harumichi Nishimura",
"Rudy Raymond",
"Shigeru Yamashita"
],
"categories": [
"quant-ph"
],
"title": "Quantum Network Coding for General Graphs",
"url": "https://arxiv.org/abs/quant-ph/0611039"
},
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