Abstract
We argue that Wigner’s friend thought experiment does not support observer dependence of quantum states. An analysis in terms of history vectors suggests that quantum collapse is to be understood as collapse of histories rather than collapse of states.
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Notes
i.e. a measurement of an observable having |0〉 and |1〉 as eigenvectors.
For an introduction to this subject, see for example the book by A. Peres [6].
since they are eigenvectors of a “position of the pointer” observable.
besides the obvious system of reference dependence of position, velocities etc.
The CNOT is a two-qubit gate acting on the computational basis as as \(|0{\rangle }|0{\rangle } \rightarrow |0\rangle |0\rangle \), \(|0\rangle |1\rangle \rightarrow |0\rangle |1\rangle \), \(|1\rangle |0\rangle \rightarrow |1\rangle |1\rangle \), \(|1\rangle |1\rangle \rightarrow |1\rangle |0\rangle \), the first qubit being the control and the second being the target.
References
Fuchs, C.A., Schack, R.: Quantum-bayesian coherence,. Rev. Mod. Phys. 85, 1693 (2013)
D: Mermin, physics: QBism puts the scientist back into science. Nature 507, 421–423 (2014)
Everett, H.: Relative state formulation of quantum mechanics. Rev. Mod. Phys. 29, 454–462 (1957)
Rovelli, C.: Relational quantum mechanics. Int. J. Theoret. Phy. 35, 1637 (1996). arXiv:9609002
Wigner, E.P. In: Good, I.J. (ed.) : In The Scientist Speculates, pp 284–302. Heinemann, Portsmouth (1961)
Peres, A.: Quantum Theory, Concepts and Methods. Kluwer, Netherlands (1995)
Castellani, L.: History operators in quantum mechanics. Int. J. Quant. Inf. 17(08), 1941001 (2019). https://doi.org/10.1142/S0219749919410016 [arXiv:1810.03624 [quant-ph]]
Castellani, L.: History entanglement entropy, Pys. Scripta 96 5, 055217 arXiv:2009.02331 [quant-ph] (2021)
Brukner, C.: On the quantum measurement problem. In: Bertlmann, R., Zeilinger, A. (eds.) Quantum [Un]Speakables II: Half a Century of Bell’s Theorem. arXiv:1507.05255, pp 95–117. Springer, New York (2017)
Frauchiger, D., Renner, R.: Quantum theory cannot consistently describe the use of itself. Nature Commun 9, 3711 (2018)
Brukner, C.: A no-go theorem for observer-independent facts. Entropy 20, 350 (2018). arXiv:1804.00749
Proietti, M., et al.: Experimental test of local observer independence. Sci. Adv. 5(9), 20 (2019). DOI:10.1126/sciadv.aaw9832, arXiv:1902.05080 [quant-ph]
Bong, K., Utreras-Alarcón, A., Ghafari, F., et al.: A strong no-go theorem on the Wigner’s friend paradox, Nat. Phys. https://doi.org/10.1038/s41567-020-0990-x(2020)
Araújo, M.: The flaw in Frauchiger and Renner’s Argument. http://mateusaraujo.info/2018/10/24/the-flaw-in-frauchiger-and-renners-argument/ (2018)
Sudbery, A.: The hidden assumptions of Frauchiger and Renner. Int. J. Quant. Foundations 5, 98 (2019). arXiv:1905.13248
Kastner, R.E.: Unitary-Only Quantum Theory Cannot Consistently Describe the Use of Itself: On the Frauchiger–Renner Paradox. Found. Phys. 50(5), 441 (2020). https://doi.org/10.1007/s10701-020-00336-6 [arXiv:2002.01456 [quant-ph]]
Acknowledgements
We thank Eric Cavalcanti and Carlo Rovelli for correspondence on recent experiments. This work is supported by the research funds of the Eastern Piedmont University and INFN - Torino Section.
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Castellani, L. No Relation for Wigner’s Friend. Int J Theor Phys 60, 2084–2089 (2021). https://doi.org/10.1007/s10773-021-04826-9
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DOI: https://doi.org/10.1007/s10773-021-04826-9