When initially disjoint observers later consult physical records, under what specified conditions should their readouts agree? This paper gives a sufficient, access-relative certification within standard quantum mechanics. This certification requires stable, repeatably readable labels, low accessible sensitivity to coherence between the corresponding outcome sectors, and, for distributed consultation, carriers encoding a common label. Sequential nondemolition readouts of a single carrier with orthonormal record labels produce memory registers whose product record-basis outcomes match with Born probability one, independently of coherence in the carrier. For disjoint carriers, if their accessible joint state is close in trace distance to the corresponding marginal of an ideal spectrum broadcast structure, disagreement is bounded by that distance and by the two local discrimination errors. In a two-outcome model, the relevant coherence belongs to the branch-bearing system-record state rather than the record-only marginal; defining dephasing and off-diagonal observables on that same space yields an interference bound. These results concern record statistics, not interpretation-neutral identity of first-person experiences or observer-independent reality. Applied to Extended Wigner’s Friend scenarios, they support ideal ask-the-friend agreement. That fixed-setting equality supplies neither the setting-indexed joint model required by Absoluteness of Observed Events in Local Friendliness nor Brukner’s common Boolean representation, and it does not entail Frauchiger and Renner’s distinct quantum certainty, inter-agent-consistency, and single-valuedness assumptions. The no-go results remain valid conditional consequences of those premises.
When initially disjoint observers later consult physical records, under what specified conditions should their readouts agree? This paper gives a sufficient, access-relative certification within standard quantum mechanics. This certification requires stable, repeatably readable labels, low accessible sensitivity to coherence between the corresponding outcome sectors, and, for distributed consultation, carriers encoding a common label. Sequential nondemolition readouts of a single carrier with orthonormal record labels produce memory registers whose product record-basis outcomes match with Born probability one, independently of coherence in the carrier. For disjoint carriers, if their accessible joint state is close in trace distance to the corresponding marginal of an ideal spectrum broadcast structure, disagreement is bounded by that distance and by the two local discrimination errors. In a two-outcome model, the relevant coherence belongs to the branch-bearing system-record state rather than the record-only marginal; defining dephasing and off-diagonal observables on that same space yields an interference bound. These results concern record statistics, not interpretation-neutral identity of first-person experiences or observer-independent reality. Applied to Extended Wigner’s Friend scenarios, they support ideal ask-the-friend agreement. That fixed-setting equality supplies neither the setting-indexed joint model required by Absoluteness of Observed Events in Local Friendliness nor Brukner’s common Boolean representation, and it does not entail Frauchiger and Renner’s distinct quantum certainty, inter-agent-consistency, and single-valuedness assumptions. The no-go results remain valid conditional consequences of those premises.
We address the screen problem—why a spatially delocalized quantum input interacting with a macroscopic detector yields a single localized, persistent dot on each trial. The approach is record-first: a dot is treated as an operationally certified record, stable, redundantly witnessed, and readable, and the measurement problem is reformulated as the problem of when such records become single-valued facts. To avoid semantic collapse, subsystem structure is grounded in locality via a net of local observable algebras rather than an assumed Hilbert-space tensor factorization. The paper then introduces an exact notion of certification in algebraic terms: distinct outcomes are exactly certified when they induce disjoint GNS representations of the quasi-local algebra, as can occur through outcome-dependent infrared or asymptotic dressing. In that regime, a Record Superselection Axiom (RSA) follows as a sector constraint on physically admissible quasi-local observables, excluding cross-sector interference measurements after certification. This yields a no-smear lemma for single events, supports the canonical Born weights on consistent record-history families, and implies a Wigner–Friend recoherence no-go past exact certification. Finally, the paper proposes an in-principle discriminator: in a complete witness-capture unmeasurement protocol, unitary-only accounts predict recoverable interference as capture and control approach unity, whereas exact sector disjointness predicts a principled obstruction once outcomes enter disjoint sectors. The result is a bounded, testable framework linking records, locality, and admissibility in a concrete resolution of the screen problem.
Abstract Decoherence suppresses interference, but an observer’s ability to reconstruct a classical pointer value depends on additional resources: distinguishable conditional environmental states, an allowed measurement, sufficient accessible fragments, and sufficiently independent records. We provide an explicit minimal quantum-to-operational bridge that places these requirements in one chain. A system qubit is correlated with conditional environmental qubit states, permitting exact expressions for residual coherence, quantum mutual information, pointer Holevo information, accessible information, and Helstrom discrimination error. Full density-matrix calculations validate the formulas across 280 endpoint and interior cases. An accessible-sector/hidden-bath construction shows that coherence can fall below 2.3 × 10⁻⁵ while the observer’s record information and error remain fixed at 0.0803 bits and 0.4009. Measurement policies shift recovery thresholds: for record overlap 0.8 and error tolerance 0.05, collective or optimized adaptive-local discrimination requires four fragments, a fixed canonical-basis measurement requires six, and repeated one-fragment Helstrom measurements followed by classical decoding require seven. More importantly, records matched at the one-fragment level can have radically different collective behavior. For a binary pointer, the common-mode classical channel has an exact accessible-information ceiling of 1 − h₂(0.1) = 0.5310 bits, while the noncommuting hidden-memory ensemble approaches the same Holevo-information ceiling; matched independent records approach one bit and zero error. Disjoint observer counts and unanimous agreement likewise depend on shared error structure. Finally, declared local measurements induce classical record channels that are subjected to held-out model selection, predictive checks, abstention, and simultaneous finite-sample threshold certification. The resulting framework supplies the validated quantum-to-operational record model used in the companion analysis of operational capacity bounds for distinguishable decoherent histories.
Abstract Decoherent-histories methods identify time-extended alternatives whose diagonal weights may support probabilistic interpretation, while environmental-record approaches ask which alternatives a specified observer can recover. We formulate their intersection as a finite branch-record packing problem generated from one cross-branch construction. A codebook is admissible only if its declared coarse-graining obeys a bounded probability-sum-rule error and its accessible states can be decoded under a specified observer policy with finite error. Uniform reweighting defines a geometric packing number; a communication interpretation additionally requires a preparation instrument. Retrospective resolution is stricter: the base history family is exhaustive, selected histories must cover sufficient physical diagonal weight and be individually recoverable, and the same declared quantum-to-classical measurement channel used for decoding must preserve approximate consistency after histories are refined by its registered outcomes. This measurement-refined condition quantitatively controls the difference between the actual outcome distribution and the normalized diagonal classical-quantum prediction. For uniform branch-record packing and its communication realizations, general converses follow from accessible dimension, fixed outcome count, Holevo-Fano information, and hypothesis testing. Exact models quantify record compression, access, memory, measurement policy, temporal dependence, and shared latent errors. In a jointly realized four-bit benchmark, scalar consistency and recovery admit six histories, whereas direct measurement-refined consistency under the declared local Helstrom instrument admits four at the same tolerances. Finite-sample procedures distinguish held-out recovery achievability, structure-conditional consistency certification, structural converses, independently constructed parameter intervals, and abstention.
This document connects Return Theory (RT) to quantum mechanics through two standard settings: Wigner's friend and quantum Darwinism. Each setting is read with RT's declared roles: record, reference, access and reconstruction. The document does not choose an interpretation of quantum mechanics and does not claim to solve the measurement problem. It states, in operational terms, what each observer can reconstruct, which reference validates that reconstruction, and when two observers can agree. Main results: • Content and phase are different records with different references. Wigner's coherence access gives no information about the friend's content (error 1/2). It records the relative phase exactly. • Record–interference complementarity (one access): (1−2ε₁)² + (1−2ε₂)² ≤ 1. Equality holds for projective measurements in the plane of the two tasks. • Two-system bound: if one system holds an ε₁-record of the content, any access to another system reads the phase with error ε₂, where 1−2ε₂ ≤ 2|αβ|·√(1−(1−2ε₁)²). • Agreement between observers follows from records when both are realised jointly in one run. Agreement alone is not a record (Bell-pair example). • Operational objectivity is defined by four conditions. In a branching environment, fragment errors are ε_f = ½(1−√(1−c^{2f})), and redundancy R_ε ≥ 2 is required. Mutual information shows a classical plateau at the pointer entropy. • Complementary tolerances for disjoint observers have a threshold of ½(1−1/√2) ≈ 0.146. A [[4,2,2]] code example shows task-separate (not simultaneous) objectivity of content and phase. All numbers in the text are generated from code (Python, exact state vectors). The package reproduces the JSON results and the generated TeX byte-for-byte. Figures may differ slightly across Matplotlib versions. Prior work (Wigner, Frauchiger–Renner, Brukner, Zurek, Englert, and others) is cited for comparison. Interactive language-model tools were used in preparing the text and code. The author is responsible for all content.
Quantum mechanics supplies outcome probabilities through the Born rule, while measurement physics describes how interactions, decoherence, amplification, and environmental encoding produce records. We reformulate quantum admissibility around the distinction between quantum support, Born probability, operational record support, and realized record. The reformulation is motivated by a no-go result for a legacy strong ansatz in which Born probabilities are multiplied by an independently specified scalar admissibility factor: independence from the Born distribution together with arbitrary coarse-graining consistency forces that factor to be uniform, while the corresponding positive-operator construction reduces to an ordinary quantum state update. Rather than replacing this failed weighting by an unstructured support predicate, we connect record support explicitly to existing quantum-to-classical formalisms. Quantum-Darwinist redundancy, classically accessible information, quantum discord, and distance to spectrum-broadcast structure provide a context-dependent operational record profile from which prospectively specified support criteria can be constructed without modifying the Born rule. We also show why Bell correlations cannot supply the missing content of a binary support relation: a non-product joint support set is shared by classically correlated systems, while generic Bell-violating distributions may have full Cartesian support and differ only in their probabilityweights. Bell and no-signaling therefore constrain any future probability-modifying extension but do not establish relational realization as a new physical quantity. The resulting framework has three levels: a conceptual grammar, an operational record-support layer entirely within standard quantum theory, and a distinct strong route requiring independently predicted deviations from the best standard quantum-plus-apparatus model. The principal claim is consequently a boundary result: objective record support can be operationalized without a second probability law, whereas the natural scalar attempt to convert such support into probability reweighting is stronglyconstrained.
Intersubjective consistency asks when different observers of a physical system, reasoning from a shared theory, will agree on their probability assessments. Classical probability theory provides a benchmark in the form of the Agreement Theorem (Aumann, 1976). We study the quantum mechanics (QM) analog to the classical Agreement Theorem in a finite-dimensional tripartite setting in which two observers obtain information via local projective measurements. We represent their mutual awareness by common certainty, which is formally an infinite hierarchy of certainty operators concerning the probability of an event of interest. We first prove that if the observers' measurements commute with one another and with the property of interest, common certainty forces their probability assessments to coincide, thereby recovering a QM analog to the classical Agreement Theorem. We then construct a one-parameter family of qutrit-qubit-qubit models in which one observer's measurement does not commute with the property and common certainty of disagreement occurs -- a distinctively QM phenomenon. The mechanism is coherence between branches distinguished by one but not the other observer's measurement. When measurement outcomes are stored in a classical register, the resulting dephasing removes this coherence and restores agreement. Finally, we prove that QM does not permit the extreme 0-1 configuration in which Alice is certain of a property and is also certain that Bob is certain of its negation. These results aim to turn debate in QM about observer-dependent facts into precise mathematical conditions for when intersubjective agreement or disagreement in QM can be sustained.