Qubit Channels Which Require Four Inputs to Achieve Capacity: Implications for Additivity Conjectures
| dc.creator | Hayashi, Masahito | |
| dc.creator | Imai, Hiroshi | |
| dc.creator | Matsumoto, Keiji | |
| dc.creator | Ruskai, Mary Beth | |
| dc.creator | Shimono, Toshiyuki | |
| dc.date | 2004-03-24 | |
| dc.date | 2004-08-26 | |
| dc.date.accessioned | 2026-07-07T06:09:23Z | |
| dc.date.available | 2026-07-07T06:09:23Z | |
| dc.description | 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. | |
| dc.description | 19 pages, 15 figures. several typos corrected in v2 | |
| dc.identifier | https://arxiv.org/abs/quant-ph/0403176 | |
| dc.identifier | http://arxiv.org/abs/quant-ph/0403176 | |
| dc.identifier | Quantum Inf. Comput. 5, 13--31 (2005) | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/91940 | |
| dc.subject | Quantum Physics | |
| dc.title | Qubit Channels Which Require Four Inputs to Achieve Capacity: Implications for Additivity Conjectures | |
| dc.type | text |