On the independence of local algebras II

Kazimierz Napiórkowski

Claudio D’Antoni

Vinitha Balachandran, Giuliano Benenti, Giulio Casati +1 more

The relaxation of out-of-time-ordered correlators (OTOCs) has been studied as a means to characterize the scrambling properties of a quantum system. We show that the presence of local conserved quantities typically results in, at the fastest, an algebraic relaxation of the OTOC provided (i) the dynamics is local and (ii) the system follows the eigenstate thermalization hypothesis. Our result relies on the algebraic scaling of the infinite-time value of OTOCs with system size, which is typical in thermalizing systems with local conserved quantities, and on the existence of finite speed of propagation of correlations for finite-range-interaction systems. We show that time independence of the Hamiltonian is not necessary as the above conditions (i) and (ii) can occur in time-dependent systems, both periodic or aperiodic. We also remark that our result can be extended to systems with power-law interactions.

Shadi Ali Ahmad, Ro Jefferson

An early result of algebraic quantum field theory is that the algebra of any subregion in a QFT is a von Neumann factor of type III _{1} 1 , in which entropy cannot be well-defined because such algebras do not admit a trace or density states. However, associated to the algebra is a modular group of automorphisms characterizing the local dynamics of degrees of freedom in the region, and the crossed product of the algebra with its modular group yields a type II _∞ ∞ factor, in which traces and hence von Neumann entropy can be well-defined. In this work, we generalize recent constructions of the crossed product algebra for the TFD to, in principle, arbitrary spacetime regions in arbitrary QFTs, formally paving the way to the study of entanglement entropy without UV divergences. In contrast to previous works, we emphasize that this construction is independent of gravity. In this sense, the crossed product construction represents a refinement of Haag’s assignment of nets of observable algebras to spacetime regions by providing a natural construction of a type II factor. We present several concrete examples: a QFT in Rindler space, a CFT in an open ball of Minkowski space, and arbitrary boundary subregions in AdS/CFT. In the holographic setting, we provide a novel argument for why the bulk dual must be the entanglement wedge, and discuss the distinction arising from boundary modular flow between causal and entanglement wedges for excited states and disjoint regions.

Klaus Fredenhagen

tovi zituny

Chronometric Closure Paper II: Channel-Projection Compatibility and the Algebraic Origin of the Chronometric Source Channels Tovi Zituny — Independent Researcher, May 2026 Overview This paper is the second in the Chronometric Closure Series. It addresses the principal open assumption of Chronometric Closure Paper I: channel-projection compatibility (condition E7). Paper I established that the generalized chronometric maintenance source J_source^general = κ_R D∂_τ log R + κ_D R∂τ log D − Ξ∇ ∇² log χ + O(∂_τ², ∇⁴, ℓ²) arises as the local Markovian limit of an admissible open chronometric environment — but only under the assumption that the environmental response projects onto the three chronometric channels D∂_τ log R, R∂_τ log D, and ∇² log χ. Paper I treated this mapping as a given. Paper II derives it as a conditional algebraic projection theorem. Main Result The paper formulates channel-projection compatibility as an algebraic projection problem over local chronometric diamonds equipped with von Neumann record algebras, Araki relative entropy, modular record transport, and split finite-rank control sectors. Three projection lemmas are proved: Lemma CP1 establishes the record-channel projection: the environmental response onto the record sector is identified with D∂_τ log R through the algebraic record-flow identity ∂_τ log R = −∂_τΣ_R, weighted by the distinguishability factor D. Lemma CP2 establishes the distinguishability-channel projection: the logarithmic variation of the chronometric product structure χ_ℓ = C_ℓ[DR] naturally decomposes into a record channel and a distinguishability channel via ∂_τ(DR) = DR(∂_τ log D + ∂_τ log R). Lemma CP3 establishes the spatial chronometric projection: local, short-range, isotropic split-sector spatial response acting on the logarithmic chronometric variable log χ yields the leading Laplacian term ∇² log χ. Conditional Theorem CP assembles the three lemmas into the full channel-projection compatibility result: under modular-record regularity, product-structure preservation, log-support compatibility, local isotropic spatial response, and admissible projection system conditions, the three E7 channels are recovered as conditional low-energy projections with explicit error terms. This upgrades E7 from an unconstrained matching assumption in Paper I to a conditional algebraic projection theorem. The admissibility conditions in Definition 4.1 are stated independently of the E7 conclusion — a non-tautology note is included to make this explicit. Claim Status The result is a conditional algebraic projection theorem at the derivation level of mathematical physics. It does not prove full algebraic universality, derive all environmental operators from a UV-complete chronometric algebra, or show that every microscopic completion must realize the same projections. An explicit limitation is that the distinguishability factor D is not derived from the record algebra in this paper; it enters as a preserved CIFT input and remains a target for deeper information-geometric or operator-algebraic work. Thirteen failure modes are identified and classified in a dedicated section. Structure The paper contains eleven sections. Sections 1–2 inherit the problem from Paper I and formulate the algebraic projection task. Section 3 establishes the algebraic record setting using local diamonds, von Neumann algebras, Araki relative entropy, and record-log flow. Section 4 develops modular record transport and three projection regimes. Sections 5–7 prove Lemmas CP1, CP2, and CP3. Section 8 assembles Conditional Theorem CP. Section 9 identifies thirteen failure modes and scope limits. Section 10 assesses implications for Paper I, CUP, and the closure programme. Section 11 concludes. A claim-status summary table is provided.