The Landau-Feynman transiently open quantum system: entanglement and density operators
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arXiv
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| Autori principali: | , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866910959797272576 |
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| author | Deville, Alain Deville, Yannick |
| author_facet | Deville, Alain Deville, Yannick |
| contents | Users of quantum mechanics, both in physics and in the field of quantum information, are familiar with the concept of a statistical mixture as introduced by von Neumann, and with the use of a density operator in that context. A density operator may also be used in another situation, introduced by Landau, with a transient coupling between the two parts of a quantum bipartite system. But more than fifty years after a clarifying work by Feynman on the subject, a confusion still persists about what we call the Landau-Feynman situation. This is specifically testified by the development of controversies around that subject. The aim of this paper is to stress that, when facing the Landau-Feynman situation, the right concept to be used is not the one of a mixed state (or statistical mixture) - be it qualified as proper or improper -, but the one of entanglement. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_15551 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Landau-Feynman transiently open quantum system: entanglement and density operators Deville, Alain Deville, Yannick Quantum Physics Users of quantum mechanics, both in physics and in the field of quantum information, are familiar with the concept of a statistical mixture as introduced by von Neumann, and with the use of a density operator in that context. A density operator may also be used in another situation, introduced by Landau, with a transient coupling between the two parts of a quantum bipartite system. But more than fifty years after a clarifying work by Feynman on the subject, a confusion still persists about what we call the Landau-Feynman situation. This is specifically testified by the development of controversies around that subject. The aim of this paper is to stress that, when facing the Landau-Feynman situation, the right concept to be used is not the one of a mixed state (or statistical mixture) - be it qualified as proper or improper -, but the one of entanglement. |
| title | The Landau-Feynman transiently open quantum system: entanglement and density operators |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2505.15551 |