Response to "The measurement postulates of quantum mechanics are not redundant"
Adrian Kent has recently presented a critique \cite{Kent} of our paper \cite{MGM} in which he claims to refute our main result: the measurement postulates of quantum mechanics can be derived from the rest of postulates, once we assume that the set of mixed states of a finite-dimensional Hilbert spac...
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| Format: | Article |
| Language: | English |
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Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften
2025-01-01
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| Series: | Quantum |
| Online Access: | https://quantum-journal.org/papers/q-2025-01-14-1592/pdf/ |
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| _version_ | 1841536352620904448 |
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| author | Lluís Masanes Thomas D. Galley Markus P. Müller |
| author_facet | Lluís Masanes Thomas D. Galley Markus P. Müller |
| author_sort | Lluís Masanes |
| collection | DOAJ |
| description | Adrian Kent has recently presented a critique \cite{Kent} of our paper \cite{MGM} in which he claims to refute our main result: the measurement postulates of quantum mechanics can be derived from the rest of postulates, once we assume that the set of mixed states of a finite-dimensional Hilbert space is finite-dimensional. To construct his argument, Kent considers theories resulting from supplementing quantum mechanics with hypothetical ``post-quantum'' measurement devices. We prove that each of these theories contains pure states (i.e. states of maximal knowledge) which are not rays of the Hilbert space, in contradiction with the ``pure state postulate'' of quantum mechanics. We also prove that these alternatives violate the finite-dimensionality of mixed states. Each of these two facts separately invalidates the refutation. In this note we also clarify the assumptions used in \cite{MGM} and discuss the notions of pure state, physical system, and the sensitivity of the structure of the state space under modifications of the measurements or the dynamics. |
| format | Article |
| id | doaj-art-b3d71ed383954fa0a75db14b7b26c87d |
| institution | Kabale University |
| issn | 2521-327X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften |
| record_format | Article |
| series | Quantum |
| spelling | doaj-art-b3d71ed383954fa0a75db14b7b26c87d2025-01-14T16:44:15ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2025-01-019159210.22331/q-2025-01-14-159210.22331/q-2025-01-14-1592Response to "The measurement postulates of quantum mechanics are not redundant"Lluís MasanesThomas D. GalleyMarkus P. MüllerAdrian Kent has recently presented a critique \cite{Kent} of our paper \cite{MGM} in which he claims to refute our main result: the measurement postulates of quantum mechanics can be derived from the rest of postulates, once we assume that the set of mixed states of a finite-dimensional Hilbert space is finite-dimensional. To construct his argument, Kent considers theories resulting from supplementing quantum mechanics with hypothetical ``post-quantum'' measurement devices. We prove that each of these theories contains pure states (i.e. states of maximal knowledge) which are not rays of the Hilbert space, in contradiction with the ``pure state postulate'' of quantum mechanics. We also prove that these alternatives violate the finite-dimensionality of mixed states. Each of these two facts separately invalidates the refutation. In this note we also clarify the assumptions used in \cite{MGM} and discuss the notions of pure state, physical system, and the sensitivity of the structure of the state space under modifications of the measurements or the dynamics.https://quantum-journal.org/papers/q-2025-01-14-1592/pdf/ |
| spellingShingle | Lluís Masanes Thomas D. Galley Markus P. Müller Response to "The measurement postulates of quantum mechanics are not redundant" Quantum |
| title | Response to "The measurement postulates of quantum mechanics are not redundant" |
| title_full | Response to "The measurement postulates of quantum mechanics are not redundant" |
| title_fullStr | Response to "The measurement postulates of quantum mechanics are not redundant" |
| title_full_unstemmed | Response to "The measurement postulates of quantum mechanics are not redundant" |
| title_short | Response to "The measurement postulates of quantum mechanics are not redundant" |
| title_sort | response to the measurement postulates of quantum mechanics are not redundant |
| url | https://quantum-journal.org/papers/q-2025-01-14-1592/pdf/ |
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