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Informational Geodesic Collapse: Dynamic Reduction of the Quantum State Governed by the Curvature of the Fisher–Bures Metric in Entangled Subsystems

Caio A. Rocha

Published Jul 18, 2026• 0 citations
Publisher

Abstract

We propose the Informational Geodesic Collapse Theory (IGCT), a stochastic extension of the projection postulate of quantum mechanics in which the rate of dynamical reduction of the state vector is not a universal parameter coupled solely to the system’s mass — as in Continuous Spontaneous Localization (CSL) and Ghirardi–Rimini–Weber (GRW) models — but a geometrically defined quantity, computed from the Ricci scalar curvature of the Bures–Uhlmann metric induced on the manifold of reduced states of a subsystem, weighted by its von Neumann entanglement entropy. The construction builds upon the already established formalism of the geometrization of quantum mechanics (projective Hilbert space as a Kähler manifold, unitary dynamics as a Hamiltonian flow) and grafts onto it a stochastic diffusion term whose coefficient — the informational curvature scalar KA(ψ) — vanishes identically for product states and grows with the degree of entanglement of the considered subsystem. We rigorously demonstrate (i) that the proposed stochastic equation preserves the norm of the state vector for any nonnegative and adapted choice of KA(ψt); (ii) that, in the limit where KA is held constant, the theory reduces exactly to the standard CSL model, inheriting its linear master equation and its proof of no superluminal signaling; (iii) that, for a two-level subsystem, the Bures metric is a space of constant scalar curvature (R = 24, isometric to a hemisphere of S 3 of radius 1/2), a result obtained by direct symbolic computation, from which it follows that KA is, in this case, strictly proportional to the entanglement entropy; and (iv), as a novel extension of this work, that for a three-level subsystem (qutrit) the scalar curvature of the isospectral leaf of the Bures metric — the flag manifold SU(3)/U(1)2 equipped with the induced metric — is not constant, having been exactly computed (via Lie algebra verified symbolically and numerically validated against the qubit case) at representative points of the eigenvalue space, with exact values between ≈ 191 and ≈ 3120 (in natural units) and a divergence as the state approaches the maximally mixed state. Complementarily, we perform a Monte Carlo stochastic simulation of Eq. (6) that numerically confirms, with excellent agreement with the analytical prediction e −2λKAt, that a highly entangled subsystem (Bell pair, KA = 24 ln 2) loses interference visibility at a rate about 330 times larger than a subsystem of identical mass and residual entanglement, numerically isolating the theory’s central phenomenological signature. Thus, the theory predicts an objective collapse rate that depends not only on mass but on the internal entanglement structure of the system — an experimentally distinguishable signature from GRW/CSL/Diósi–Penrose models, testable in optomechanical interferometry with controlled pre-entanglement. We honestly discuss the limitations of the proposal: the absence of superluminal signaling in the fully state-dependent regime remains conjectural, a relativistically covariant generalization is not constructed here, and the exact computation Informational Geodesic Collapse 2of R[gBures] for d ≥ 3 remains restricted, in this version, to the isospectral leaf (the full flag manifold of D(HA) in dimension 3, including the radial directions of the spectrum, has not been computed). The IGCT is resented as a mathematically well-posed and falsifiable research program, not as an established fact of nature.

DOI
10.5281/zenodo.21432634

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We propose the Informational Geodesic Collapse Theory (IGCT), a stochastic extension of the projection postulate of quantum mechanics in which the rate of dynamical reduction of the state vector is not a universal parameter coupled solely to the system’s mass — as in Continuous Spontaneous Localization (CSL) and Ghirardi–Rimini–Weber (GRW) models — but a geometrically defined quantity, computed from the Ricci scalar curvature of the Bures–Uhlmann metric induced on the manifold of reduced states of a subsystem, weighted by its von Neumann entanglement entropy. The construction builds upon the already established formalism of the geometrization of quantum mechanics (projective Hilbert space as a Kähler manifold, unitary dynamics as a Hamiltonian flow) and grafts onto it a stochastic diffusion term whose coefficient — the informational curvature scalar KA(ψ) — vanishes identically for product states and grows with the degree of entanglement of the considered subsystem. We rigorously demonstrate (i) that the proposed stochastic equation preserves the norm of the state vector for any nonnegative and adapted choice of KA(ψt); (ii) that, in the limit where KA is held constant, the theory reduces exactly to the standard CSL model, inheriting its linear master equation and its proof of no superluminal signaling; (iii) that, for a two-level subsystem, the Bures metric is a space of constant scalar curvature (R = 24, isometric to a hemisphere of S 3 of radius 1/2), a result obtained by direct symbolic computation, from which it follows that KA is, in this case, strictly proportional to the entanglement entropy; and (iv), as a novel extension of this work, that for a three-level subsystem (qutrit) the scalar curvature of the isospectral leaf of the Bures metric — the flag manifold SU(3)/U(1)2 equipped with the induced metric — is not constant, having been exactly computed (via Lie algebra verified symbolically and numerically validated against the qubit case) at representative points of the eigenvalue space, with exact values between ≈ 191 and ≈ 3120 (in natural units) and a divergence as the state approaches the maximally mixed state. Complementarily, we perform a Monte Carlo stochastic simulation of Eq. (6) that numerically confirms, with excellent agreement with the analytical prediction e −2λKAt, that a highly entangled subsystem (Bell pair, KA = 24 ln 2) loses interference visibility at a rate about 330 times larger than a subsystem of identical mass and residual entanglement, numerically isolating the theory’s central phenomenological signature. Thus, the theory predicts an objective collapse rate that depends not only on mass but on the internal entanglement structure of the system — an experimentally distinguishable signature from GRW/CSL/Diósi–Penrose models, testable in optomechanical interferometry with controlled pre-entanglement. We honestly discuss the limitations of the proposal: the absence of superluminal signaling in the fully state-dependent regime remains conjectural, a relativistically covariant generalization is not constructed here, and the exact computation Informational Geodesic Collapse 2of R[gBures] for d ≥ 3 remains restricted, in this version, to the isospectral leaf (the full flag manifold of D(HA) in dimension 3, including the radial directions of the spectrum, has not been computed). The IGCT is resented as a mathematically well-posed and falsifiable research program, not as an established fact of nature.
We discuss a model of spontaneous collapse of the quantum state that does not require adding any stochastic processes to the standard dynamics. The additional ingredient with respect to the wave function is a position in the configuration space which drives the collapse in a completely deterministic way. This new variable is equivalent to a set of positions of all the particles, i.e., a set of Bohmian positions, which obey the usual guiding equation of Bohmian theory. Any superposition of quantum states of a macroscopic object occupying different regions of space is projected by a localization process onto the region occupied by the positions. Since the Bohmian positions are well defined in a single realization of the experiment, a space localization into one region is produced. The mechanism is based on the correlations between these positions arising from the cohesive forces inside macroscopic objects. The model introduces two collapse parameters which play a role very similar to those of the Ghirardi-Rimini-Weber (GRW) [Ghirardi et al., Phys. Rev. D 34, 470 (1986)] and continuous spontaneous localization (CSL) [Pearle, Phys. Rev. A 39, 2277 (1989); Ghirardi et al., Phys. Rev. A 42, 78 (1990)] theories. With appropriate values of these parameters, we check that the corresponding dynamics rapidly projects superpositions of macroscopic states localized in different regions of space into a single region, while it maintains a negligible effect in all situations where the predictions of standard quantum dynamics are known to be correct. We briefly speculate about the possible relations with gravity. We then study the evolution of the density operator and a mean-field approximation of the dynamical equations of this model, as well as the change of the evolution of the momentum introduced by the localization process. Possible theoretical interpretations are discussed. Generally speaking, this model introduces a sharper border between the quantum and classical worlds than the GRW and CSL theories and leaves a broader range of acceptable values for the parameters.
Quantum information theory is traditionally formulated on projective state spaces, where the qubit is a point in ℂP¹. We introduce a new computational primitive—"the flubit"—defined as a point in the flag manifold Fl₁,₂(ℂ³), representing a line ℓ inside a plane P in ℂ³. This extends the hierarchy: bit → qubit → qutrit → flubit{0,1} → ℂP¹ → ℂP² → Fl₁,₂(ℂ³) Unlike projective spaces, the flag manifold carries intrinsic hierarchy: coarse (plane), fine (line), and their coupling via connection curvature Ω. We construct the Fisher information geometry of Fl₁,₂(ℂ³) and show it decomposes into base, fiber, and cross-term contributions. The cross-term vanishes for separable states and is nonzero precisely when the Weyl relation x² + xy + y² = 0 is activated. This yields a reinterpretation: entanglement is not a relation between subsystems, but the internal coherence of a single flubit. Standard two-qubit entanglement arises as the residual correlation left after projecting away the flag structure. We define the flubit–projective gap Δ(ψ), the excess Fisher information accessible through hierarchical measurements beyond independent projective ones. Δ(ψ) quantifies entanglement and provides a candidate measure of quantum computational advantage. On the product manifold M = Fl₁,₂(ℂ³) × ℂP¹, three structures coincide: Kähler geometry = quantized phase space (Kay) = information geometry (Fisher/Braunstein–Caves) Finally, we compute the Ricci curvature of the flag Fisher metric and show its eigenvalue structure constrains the gauge coupling hierarchy, with the Einstein constant λ = 2 emerging as the Ricci normalization. The flubit is the first non-projective computational primitive, and the flag manifold provides the minimal geometry where hierarchy, entanglement, and information are unified.
We propose a model of objective wave-function collapse in which reduction is triggered not by a fixed rate or by gravitational self-energy alone, but by the approach of the reduced von Neu- mann entropy SvN toward a fraction η of the Bekenstein bound IBek applicable to the system. Dynamics are governed by a Lindblad master equation with a position-based collapse operator in- herited from Continuous Spontaneous Localization (CSL), supplemented by a feedback function F(SvN /ηIBek) = (1 − SvN /ηIBek) −1 that diverges as the system approaches informational satura- tion. The model recovers the Di´osi Penrose (DP) timescale in the limit SvN ≪ ηIBek, resolves a divergence present in the predecessor “Stochastic Rupture” model for d ≫ σx, and makes a qualita- tively new prediction absent from both DP and CSL: systems with high entanglement entropy but no spatial superposition should undergo collapse on timescales of order τ ∼ γ −1 0 (1 − η), potentially as short as 10−8 s for macroscopic entangled systems. We identify explicitly every postulate and every regime of approximation.
The state space of a quantum mechanical system is a complex projective space, the space of rays in the associated Hilbert space. The state space comes equipped with a natural Riemannian metric (the Fubini-Study metric) and a compatible symplectic structure. The operations of ordinary quantum mechanics can thus be reinterpreted in the language of differential geometry. It is interesting in this spirit to scrutinize the probabilistic assumptions that are brought in at various stages in the analysis of quantum dynamics, particularly in connection with state vector reduction. A promising approach to understanding reduction, studied recently by a number of authors, involves the use of nonlinear stochastic dynamics to modify the ordinary linear Schrodinger evolution. Here we use stochastic differential geometry to give a systematic geometric formulation for such stochastic models of state vector collapse. In this picture, the conventional Schrodinger evolution, which corresponds to the unitary flow associated with a Killing vector of the Fubini-Study metric, is replaced by a more general stochastic flow on the state manifold. In the simplest example of such a flow, the volatility term in the stochastic differential equation for the state trajectory is proportional to the gradient of the expectation of the Hamiltonian. The conservation of energy is represented by the requirement that the actual process followed by the expectation of the Hamiltonian, as the state evolves, should be a martingale. This requirement implies the existence of a nonlinear term in the drift vector of the state process, which is always oriented opposite to the direction of increasing energy uncertainty. As a consequence, the state vector necessarily collapses to an energy eigenstate, and a martingale argument can be used to show that the probability of collapse to a given eigenstate, from any particular initial state, is, in fact, given by precisely the usual quantum mechanical probability.
We present the IRQS hypothesis, a phenomenological extension of standard non-relativistic quantum mechanics and the Lindblad open-systems formalism. IRQS retains unitary and Lindblad evolution below a critical threshold and introduces an additional postulate of objective reduction: instantaneous Born-rule projection occurs when the local rate of growth of the entanglement entropy of a subsystem exceeds a universal constant. The model eliminates the external observer from the measurement postulate, provides a quantitative local criterion (structurally similar to, but mechanistically distinct from, GRW and Diósi–Penrose models), and yields falsifiable predictions distinguishing it from standard decoherence theory: step-like jumps in fringe visibility and in the second-order correlation function at calculable photon-number thresholds, as well as abrupt termination of coherence in trapped-ion and SPDC platforms. We derive the threshold-interaction estimate, discuss the epistemic status of each level of the model, and propose concrete experimental protocols for measuring the universal constant in existing ytterbium ion-trap and optical SPDC setups.
We develop an information-geometric framework for analyzing quantum state-update processes generated by explicit collapse dynamics. Whereas a purely geometric description characterizes collapse as a finite displacement between an initial and a final statistical state, the present approach incorporates the dynamical law governing the intermediate evolution. A quantum state is represented by a density operator ρ(t) satisfying a specified dynamical equation, dρdt=C[ρ,t], or, more generally, by a unitary-plus-collapse evolution in which the collapse contribution is explicitly identified. The resulting trajectory is embedded in the statistical manifold of quantum states and analyzed using the quantum Fisher information metric. This allows one to define the instantaneous Fisher speed, the information-geometric length of the collapse trajectory, and an integrated geometric cost associated with the dynamical state change. The framework also permits comparison between the actual trajectory generated by a collapse model and the corresponding Fisher-geodesic trajectory connecting the same initial and final states. Relative entropy provides a complementary global measure of the distinguishability generated by the evolution, while the quantum Fisher metric characterizes its local statistical structure. The formalism is constructed so that different dynamical collapse proposals can be analyzed within a common geometric language without assuming that the geometric quantities themselves constitute a collapse mechanism: this is a diagnostic framework rather than a mechanism. In particular, once a specific collapse generator is supplied, the framework can determine how its parameters, localization properties, stochasticity, and time scale are reflected in the geometry of the associated state trajectory. The resulting formulation therefore provides a bridge between dynamical models of wave-function collapse and the information geometry of a quantum state space, while preserving the distinction between a physical collapse law and its geometric characterization.