dorsal/arxiv
View SchemaQubit Channels Which Require Four Inputs to Achieve Capacity: Implications for Additivity Conjectures
| Authors | Masahito Hayashi, Hiroshi Imai, Keiji Matsumoto, Mary Beth Ruskai, Toshiyuki Shimono |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0403176 |
| URL | https://arxiv.org/abs/quant-ph/0403176 |
| Journal | Quantum Inf. Comput. 5, 13--31 (2005) |
Abstract
An example is given of a qubit quantum channel which requires four inputs to maximize the Holevo capacity. The example is one of a family of channels which are related to 3-state channels. The capacity of the product channel is studied and numerical evidence presented which strongly suggests additivity. The numerical evidence also supports a conjecture about the concavity of output entropy as a function of entanglement parameters. However, an example is presented which shows that for some channels this conjecture does not hold for all input states. A numerical algorithm for finding the capacity and optimal inputs is presented and its relation to a relative entropy optimization discussed.
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"abstract": "An example is given of a qubit quantum channel which requires four inputs to\nmaximize the Holevo capacity. The example is one of a family of channels which\nare related to 3-state channels. The capacity of the product channel is studied\nand numerical evidence presented which strongly suggests additivity. The\nnumerical evidence also supports a conjecture about the concavity of output\nentropy as a function of entanglement parameters. However, an example is\npresented which shows that for some channels this conjecture does not hold for\nall input states. A numerical algorithm for finding the capacity and optimal\ninputs is presented and its relation to a relative entropy optimization\ndiscussed.",
"arxiv_id": "quant-ph/0403176",
"authors": [
"Masahito Hayashi",
"Hiroshi Imai",
"Keiji Matsumoto",
"Mary Beth Ruskai",
"Toshiyuki Shimono"
],
"categories": [
"quant-ph"
],
"journal_ref": "Quantum Inf. Comput. 5, 13--31 (2005)",
"title": "Qubit Channels Which Require Four Inputs to Achieve Capacity: Implications for Additivity Conjectures",
"url": "https://arxiv.org/abs/quant-ph/0403176"
},
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