Wigner's Friend paradoxes: consistency with weak-contextual and weak-macroscopic realism models
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arXiv
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| Autori principali: | , , , , , , |
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| Natura: | Preprint |
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2022
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| author | Joseph, Ria Thenabadu, Manushan Hatharasinghe, Channa Fulton, Jesse Teh, Run-Yan Drummond, P. D. Reid, M. D. |
| author_facet | Joseph, Ria Thenabadu, Manushan Hatharasinghe, Channa Fulton, Jesse Teh, Run-Yan Drummond, P. D. Reid, M. D. |
| contents | Wigner's friend paradoxes highlight contradictions between measurements made by Friends inside a laboratory and superobservers outside a laboratory, who have access to an entangled state of the measurement apparatus. The contradictions lead to no-go theorems for observer-independent facts, thus challenging concepts of objectivity. Here, we examine the paradoxes from the perspective of establishing consistency with macroscopic realism. We present versions of the Brukner-Wigner-friend and Frauchiger-Renner paradoxes in which the spin-$1/2$ system measured by the Friends corresponds to two macroscopically distinct states. The local unitary operations $U_θ$ that determine the measurement setting $θ$ are carried out using nonlinear interactions, thereby ensuring measurements need only distinguish between the macroscopically distinct states. The macroscopic paradoxes are perplexing, seemingly suggesting there is no objectivity in a macroscopic limit. However, we demonstrate consistency with a contextual weak form of macroscopic realism (wMR): The premise wMR asserts that the system can be considered to have a definite spin outcome $λ_θ$, at the time after the system has undergone the unitary rotation $U_θ$ to prepare it in a suitable pointer basis. We further show that the paradoxical outcomes imply failure of deterministic macroscopic local realism, and arise when there are unitary interactions $U_θ$ occurring due to a change of measurement setting at both sites, with respect to the state prepared by each Friend. In models which validate wMR, there is a breakdown of a subset of the assumptions that constitute the Bell-Locality premise. A similar interpretation involving a weak contextual form of realism exists for the original paradoxes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2211_02877 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Wigner's Friend paradoxes: consistency with weak-contextual and weak-macroscopic realism models Joseph, Ria Thenabadu, Manushan Hatharasinghe, Channa Fulton, Jesse Teh, Run-Yan Drummond, P. D. Reid, M. D. Quantum Physics Wigner's friend paradoxes highlight contradictions between measurements made by Friends inside a laboratory and superobservers outside a laboratory, who have access to an entangled state of the measurement apparatus. The contradictions lead to no-go theorems for observer-independent facts, thus challenging concepts of objectivity. Here, we examine the paradoxes from the perspective of establishing consistency with macroscopic realism. We present versions of the Brukner-Wigner-friend and Frauchiger-Renner paradoxes in which the spin-$1/2$ system measured by the Friends corresponds to two macroscopically distinct states. The local unitary operations $U_θ$ that determine the measurement setting $θ$ are carried out using nonlinear interactions, thereby ensuring measurements need only distinguish between the macroscopically distinct states. The macroscopic paradoxes are perplexing, seemingly suggesting there is no objectivity in a macroscopic limit. However, we demonstrate consistency with a contextual weak form of macroscopic realism (wMR): The premise wMR asserts that the system can be considered to have a definite spin outcome $λ_θ$, at the time after the system has undergone the unitary rotation $U_θ$ to prepare it in a suitable pointer basis. We further show that the paradoxical outcomes imply failure of deterministic macroscopic local realism, and arise when there are unitary interactions $U_θ$ occurring due to a change of measurement setting at both sites, with respect to the state prepared by each Friend. In models which validate wMR, there is a breakdown of a subset of the assumptions that constitute the Bell-Locality premise. A similar interpretation involving a weak contextual form of realism exists for the original paradoxes. |
| title | Wigner's Friend paradoxes: consistency with weak-contextual and weak-macroscopic realism models |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2211.02877 |