Recoverability of quantum coherence is formulated as a family of success-constrained operational frontiers indexed by a state, channel, or multi-time process, a task, an interface, and an exact- or minimum-success convention. The framework separates state ceilings from experimentally reachable performance and distinguishes restrictions due to control, time, uncertainty, environmental records, memory, and inaccessible channel structure. The manuscript develops a typed simulation preorder on complete response families, a compiler-relative closure order, and a directed response deficiency on success-tagged behaviors. It gives exact static trace-norm ceilings, success-frontier geometry, explicit memory and record benchmarks, primal-dual finite-experiment separation programs, and reference-assisted channel-lineage witnesses. “Shadow activation” denotes the interface-relative exposure of a pre-existing process distinction under an enriched tester interface; it is not proposed as a new microscopic law. Version 1.0 follows a claim-by-claim bibliography and content audit. It is a separate work, conceptually derived in part from the earlier Italian criterion DOI 10.5281/zenodo.21333992, but it is neither a translation nor a new version of that record. This is a theoretical preprint and has not been peer reviewed.
Recoverability of quantum coherence is formulated as a family of success-constrained operational frontiers indexed by a state, channel, or multi-time process, a task, an interface, and an exact- or minimum-success convention. The framework separates state ceilings from experimentally reachable performance and distinguishes restrictions due to control, time, uncertainty, environmental records, memory, and inaccessible channel structure. The manuscript develops a typed simulation preorder on complete response families, a compiler-relative closure order, and a directed response deficiency on success-tagged behaviors. It gives exact static trace-norm ceilings, success-frontier geometry, explicit memory and record benchmarks, primal-dual finite-experiment separation programs, and reference-assisted channel-lineage witnesses. “Shadow activation” denotes the interface-relative exposure of a pre-existing process distinction under an enriched tester interface; it is not proposed as a new microscopic law. Version 1.0 follows a claim-by-claim bibliography and content audit. It is a separate work, conceptually derived in part from the earlier Italian criterion DOI 10.5281/zenodo.21333992, but it is neither a translation nor a new version of that record. This is a theoretical preprint and has not been peer reviewed.
Quantum records may be well encoded upstream yet fail to support downstream inference when routing, decoder resources, memory, or comparison channels are restricted. We analyze finite routed quantum-record networks using task-specific Bayes risk. Three exact results provide the constructive core. First, a single Bell-coded pair supplied as the same complete input to GLOBAL and finite-round LOCC-late decoders yields the risk gap qμ/2, where q is pair-delivery probability and μ retained coherence; memory policy determines whether this access is preserved. Second, fixing local binary experiments with error rates 0.20 and 0.30, we determine the entire compatible joint-risk interval [0.15, 0.20] and an attaining decoder with minimax risk 0.20 that does not know the coupling. Third, a binary sufficient-statistic delivery law is attained by a three-record majority compression with nonzero raw risk, yielding a tight physical reconstruction defect. A generated-outcome model gives an exact receiver-availability boundary, while four reduced-description witnesses and continuity bounds delineate when source, state/resource, local-coupling, or clock/memory information is insufficient. The results distinguish record formation, receiver use, memory retention, and task-adequate comparison within standard finite quantum processes. Author manuscript, preprint version 1.0. This manuscript is not a peer-reviewed journal publication. A separate technical Supplement provides complete model definitions, proofs, channel specifications and numerical details. Reproducibility materials are available separately as Software release 1.3 on OSF: https://doi.org/10.17605/OSF.IO/5TDRB. The preprint and reproducibility record are separate, linked scholarly outputs.
This preprint develops a framework for intervention-relative predictive memory: the minimum information that must be retained about the past in order to predict every future experiment allowed by a declared intervention set.For finite-dimensional linear processes, predictive memory is characterized exactly by a reachable-observable quotient and the rank of the corresponding past-future Hankel response matrix. The paper derives finite certification procedures, monotonicity under richer control, a decomposition of memory growth into reachability expansion and visibility activation, symmetry-protected compression, and no-compression results under sufficiently rich intervention algebras.The framework is connected to process-tensor bond rank, hidden-memory realization, and physical memory costs. At a prepare-and-measure temporal cut, linear, classical, and quantum memory are distinguished through ordinary rank, nonnegative rank, and positive-semidefinite rank. A robust quantum-dimension witness is derived for an n-message decoding task.A proposed single-photon spatial-mode experiment provides a concrete test. Phase-coded histories have identical present path-intensity distributions but can be perfectly distinguished by permitted future phase and Fourier operations, giving an ideal response matrix equal to the identity. For 17 modes, sufficiently high decoding success directly certifies a 17-dimensional quantum memory.The paper distinguishes established realization, automata, process-tensor, quantum-control, and factorization results from the proposed synthesis and experimental interpretation. It concludes with two natural next directions: experimental implementation and a multitime completely-positive / PSD-rank theory of intervention-relative quantum memory.
This record contains version 2 of the preprint “Identifiability Limits in Experimental Tests of Quantum Collapse.” It supersedes the conceptually broader first version deposited under DOI 10.5281/zenodo.19617199 and substantially revises the framing, formal results and experimental analysis. The paper formulates experimental tests of objective-collapse dynamics as an operational identifiability problem. It shows that finite accessible CPTP process statistics cannot uniformly distinguish fundamental nonunitarity from an unrestricted unitary-environment dilation. It then separates visibility loss, record formation and global measurement access, and derives a nuisance-profiled Fisher-information criterion for determining when complementary measurement channels jointly identify a shared collapse-parameter vector. A four-arm matched-control architecture is proposed that combines baseline stability, coherent reversibility, calibrated decoherence, durable-record formation and at least one independent side-effect channel. The result is a falsifiable experimental decision framework and a boundary on what accessible data can establish; it is not presented as an ontological solution of the quantum measurement problem. A major technical revision is available as version 3 under DOI 10.5281/zenodo.22072199. This record contains version 2 of the preprint “Identifiability Limits in Experimental Tests of Quantum Collapse.” It supersedes the conceptually broader first version deposited under DOI 10.5281/zenodo.19617199 and substantially revises the framing, formal results and experimental analysis. The paper formulates experimental tests of objective-collapse dynamics as an operational identifiability problem. It shows that finite accessible CPTP process statistics cannot uniformly distinguish fundamental nonunitarity from an unrestricted unitary-environment dilation. It then separates visibility loss, record formation and global measurement access, and derives a nuisance-profiled Fisher-information criterion for determining when complementary measurement channels jointly identify a shared collapse-parameter vector. A four-arm matched-control architecture is proposed that combines baseline stability, coherent reversibility, calibrated decoherence, durable-record formation and at least one independent side-effect channel. The result is a falsifiable experimental decision framework and a boundary on what accessible data can establish; it is not presented as an ontological solution of the quantum measurement problem. Files in this record:1. Main preprint PDF.2. Reproducibility package containing the journal-neutral source, editable manuscript, original figures, deterministic calculation and figure-generation code, machine-readable results, citation metadata and SHA-256 checksums. The included calculations are deterministic mathematical and synthetic checks; they are not experimental validation.
We formulate a contract-relative operational test for whether future-predictive quantum information lies in the post-processing capability of any admissible present description. For a declared present-access family and typed recovery policy, the present-completion deficiency is the diamond-norm distance between the predictive target and a contract-defined present-capability set. The underlying quantum channel deficiency and sufficiency mathematics is established prior art; the contribution is its use inside a path-sensitive black-hole reconstruction framework that separates coarse endpoint from rich present state, claim descent from witness descent, information insufficiency from failure of joint realizability, and local recovery from path monodromy. We prove access- and target-monotonicity under explicit typed closure conditions, give a pairwise distinguishability-gap lower bound, state a finite-dimensional attainment criterion for finitely many compact channel-type components, and derive the single/joint/virtual access hierarchy. The exact [[5,1,3]] perfect-code benchmark covers all ten three-retained and all ten two-retained access channels: every three-retained channel is exactly reversible, every two-retained channel is completely depolarizing with optimal diamond-norm deficiency 3/2 to the logical identity, and a Bell-projector discrimination certificate attains that lower bound. Two distinct three-retained erasure histories have the same coarse endpoint but different rich-present channels while both remain exactly recoverable, providing a direct null calibration of the endpoint split. The Bousso-Kaya-Lin-Shahbazi-Moghaddam finite-region family is retained as a coarse-data insufficiency benchmark, not yet as a no-present-completion theorem. The next black-hole-specific target is a certified positive fiberwise completion lower bound surviving operational quotienting, joint-realizability controls, and declared contract variations.
This preprint studies operational equivalence and recovery in a twenty-dimensional residual system with a fixed four-sector representation of dimensions 8, 8, 2 and 2. It distinguishes what a declared observation algebra can detect, what a channel preserves, and what a retained classical record makes recoverable. Record-resolved criteria separate useful reversible-error records from unrelated labels and measured-sector records, even when the discarded channel is the same. For a specified coarse-record model, the work identifies exactly recoverable observable algebras and proves an optimal entanglement-fidelity expression on a fixed four-state orbit code. Preparation-aware recovery is then classified over all one-use isometric subspaces in the stated family. An explicit ten-dimensional marker code attains exact recovery under a specified stochastic record where the whole-sector support restriction permits only eight dimensions. Its encoding, nonbaseline marker measurement, and conditional inverse operations remain supplied resources. Scoped Lean evidence verifies the explicit arbitrary-complex-matrix recovery construction and related finite identities; it does not formalize the general complete-positivity/reference framework or optimal-dimension theorem. The recorded-error model is not derived from the companion exchange-timing model, and no protection of its long pulse sequence is claimed.
This paper extends the Ontological Totality Functional (OTF) programme into the domain of quantum causal structure. Its central claim is that physical admissibility cannot be exhausted by state-level consistency or dynamical stability alone. It must also constrain the admissibility of causal organization itself. The paper introduces a causal defect functional for higher-order quantum processes and argues that definite causal order can emerge as a limiting case of admissible structure. Working in a finite-dimensional process-matrix setting, the paper defines the causal defect as the trace-norm distance to the set of valid causally separable processes with fixed normalization. It proves that this defect is non-negative, vanishes exactly on the causally separable set, and is convex. A free class of admissible supermaps is then identified: linear maps on processes that preserve validity, preserve causal separability, and are contractive in trace norm. Under these maps, the causal defect is monotone. An exact dual operational characterization is established: the causal defect equals the maximal bounded-test advantage over the causally separable set for Hermitian tests of bounded operator norm. In this sense, bounded causal witnesses arise as certified lower-bound functionals for admissibility. To connect the formalism to concrete physical scenarios, the paper studies a dephased-switch family W_eta = W_diag + eta X, where W_diag is causally separable and X encodes interference between orders. For this family, the defect is bounded above linearly in |eta|, while a witness with positive overlap on X yields a matching linear lower bound. As eta tends to zero, the process approaches definite-order admissibility. Within the OTF series, this paper functions as a frontier extension. Paper I introduced physical admissibility mathematically, Paper II studied admissibility in a tensor-cosmology channel, and Paper III interpreted admissibility ontologically. Paper IV shows that the same programme can be pushed into higher-order causal structure, where admissibility constrains not only which states and channels are physically stable but also which causal architectures can count as physically realized. Companion records in the OTF series:OTF I — DOI: 10.5281/zenodo.19068375OTF II — DOI: 10.5281/zenodo.19075284OTF Master Edition — DOI: 10.5281/zenodo.19077303