Evidence of Uncollapsed Quantum Amplitudes After Consecutive Measurements

Fuente: arXiv
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Auteurs principaux: Adami, Christoph, Giner, Lambert, Lundeen, Jeff S., Abrahao, Raphael A.
Format: Preprint
Publié: 2026
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author Adami, Christoph
Giner, Lambert
Lundeen, Jeff S.
Abrahao, Raphael A.
author_facet Adami, Christoph
Giner, Lambert
Lundeen, Jeff S.
Abrahao, Raphael A.
contents Two of the most common interpretations of quantum measurement disagree about the fate of quantum amplitudes after measurement, yet this disagreement has not previously led to experimentally distinguishable predictions. In the standard collapse picture, commonly linked to the Copenhagen interpretation of quantum mechanics, measurements eliminate unrealized amplitudes without leaving a memory. In contrast, in the unitary theory, the measurement device registers one of the possible outcomes while remaining part of an entangled state that continues to harbor the unrealized amplitudes. This persistence arises naturally under unitary evolution, since a measurement device that is part of an entangled system cannot serve as a faithful probe of the joint quantum state. Using single-photon measurements of a tunable quantum state, we experimentally show that these two theories make different predictions when three or more consecutive measurements are performed on the same quantum system. Analysis of the joint density matrix of the three measurements reveals coherence among them and supports the unitary theory of quantum measurement. When decoherence is explicitly introduced, the joint density matrix of the quantum system of interest and the apparatus becomes consistent with what a collapse theory would predict. This work clarifies the dynamics of consecutive quantum measurements and offers new insights into the interpretation of quantum measurements.
format Preprint
id arxiv_https___arxiv_org_abs_2603_13974
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Evidence of Uncollapsed Quantum Amplitudes After Consecutive Measurements
Adami, Christoph
Giner, Lambert
Lundeen, Jeff S.
Abrahao, Raphael A.
Quantum Physics
Optics
Two of the most common interpretations of quantum measurement disagree about the fate of quantum amplitudes after measurement, yet this disagreement has not previously led to experimentally distinguishable predictions. In the standard collapse picture, commonly linked to the Copenhagen interpretation of quantum mechanics, measurements eliminate unrealized amplitudes without leaving a memory. In contrast, in the unitary theory, the measurement device registers one of the possible outcomes while remaining part of an entangled state that continues to harbor the unrealized amplitudes. This persistence arises naturally under unitary evolution, since a measurement device that is part of an entangled system cannot serve as a faithful probe of the joint quantum state. Using single-photon measurements of a tunable quantum state, we experimentally show that these two theories make different predictions when three or more consecutive measurements are performed on the same quantum system. Analysis of the joint density matrix of the three measurements reveals coherence among them and supports the unitary theory of quantum measurement. When decoherence is explicitly introduced, the joint density matrix of the quantum system of interest and the apparatus becomes consistent with what a collapse theory would predict. This work clarifies the dynamics of consecutive quantum measurements and offers new insights into the interpretation of quantum measurements.
title Evidence of Uncollapsed Quantum Amplitudes After Consecutive Measurements
topic Quantum Physics
Optics
url https://arxiv.org/abs/2603.13974