We identify a regime of open quantum system dynamics in which the observed coherence time exhibits a discontinuous transitionarising from selective loss of accessibility ofan effective decoherence channel. Within theGaussian influence-functional formalism, normalization of the Keldysh weight matrix leadsto a parameter-independent coherence-timeratioR≡ τpostτpre = 43 .The result follows entirely from standardopen-system theory and introduces no modification of quantum mechanics. The predicted transition differs fundamentally fromknowndynamical-decoupling fixed points, occurring in time at fixed control parametersand remaining independent of pulse number.Because the framework yields explicit falsification criteria, the predicted ratio providesa direct experimental probe of multi-channeldecoherence structure. The analysis suggeststhat R = 4/3 represents a structural invariant associated with the normalized geometryof the Keldysh representation.
We identify a regime of open quantum system dynamics in which the observed coherence time exhibits a discontinuous transitionarising from selective loss of accessibility ofan effective decoherence channel. Within theGaussian influence-functional formalism, normalization of the Keldysh weight matrix leadsto a parameter-independent coherence-timeratioR≡ τpostτpre = 43 .The result follows entirely from standardopen-system theory and introduces no modification of quantum mechanics. The predicted transition differs fundamentally fromknowndynamical-decoupling fixed points, occurring in time at fixed control parametersand remaining independent of pulse number.Because the framework yields explicit falsification criteria, the predicted ratio providesa direct experimental probe of multi-channeldecoherence structure. The analysis suggeststhat R = 4/3 represents a structural invariant associated with the normalized geometryof the Keldysh representation.
This work develops a structural framework for accessibility-loss events in open-system decoherence under fixed control. Instead of focusing on externally tuned filter-function changes, the analysis centers on the reduced decoherence functional χ(T), which is decomposed into positive effective contributions within an additive Gaussian description. An accessibility-loss event is defined as a fixed-control transition in which one effective contribution ceases to participate within the coherence-estimation window. The primary invariant of the event is the event amplitude f(T)=1−χpost(T)χpre(T), which measures the lost fraction of the pre-event decoherence functional. We show that f(T) is scale-invariant, depends only on participation structure, and that event existence is equivalent to f(T)>0. Numerical ratios such as pre/post coherence-time ratios are therefore derived quantities, not defining features of the event. A sharp-switch limit is derived: when the suppression timescale is short compared with the estimation window and the remaining background varies more slowly, a smooth microscopic suppression appears as an effectively discontinuous jump in window-averaged observables. This leads to a two-layer falsification structure: (1) falsification of event existence (whether f>0), and (2) falsification of subclass-specific benchmark values. As an illustration, we identify a symmetric normalized subclass in which the fluctuation-sector contributions satisfy a normalized isotropic structure, yielding f=14,R=TpostTpre=43 within the single-rate regime. These values are not universal constants of open-system decoherence but benchmark invariants of this restricted structural subclass. The framework clarifies that decoherence encodes not only spectral and control information but also participation structure—which effective contributions are active within the observation window and when that participation changes. Accessibility-loss events thus represent structurally identifiable transitions in reduced decoherence geometry, independent of microscopic realization.
Dynamical-decoupling spectroscopy using solid-state spin qubits provides a powerful probe of environmental noise across wide frequency ranges. Here we identify a previously unrecognized observable fixed-point behavior in decoherence dynamics arising from additive decoherence channels sampled under narrow-band spectral filtering. We show that the ratio of decoherence times between two experimentally distinguishable configurations converges to a parameter-independent plateau value R ≈ 4/3 over an intermediate range of pulse numbers. This fixed point is independent of microscopic noise models and admits a natural geometric interpretation in terms of decoherence channel structure in the influence-functional description of open quantum systems. A central consequence is a strong experimental prediction: the existence of the plateau requires a band-limited spectral distortion, such that reconstructed noise spectra satisfy S_XY(ω)/S_CPMG(ω) ≈ 4/3 within a finite frequency window while approaching unity outside it. Numerical simulations demonstrate robustness of the effect across realistic noise environments without parameter fine tuning. We further propose an experimentally accessible protocol based solely on standard dynamical-decoupling measurements on a single qubit, enabling direct falsification of the predicted behavior. More broadly, these results indicate that measurement filtering can generate emergent invariant structures in open quantum-system dynamics, suggesting a new organizing principle for interpreting decoherence spectroscopy across quantum sensing platforms. Version 2 (v2) update: This version clarifies the logical structure of the paper by separating the existence of the measurement-induced plateau from the specific benchmark value R=4/3R=4/3R=4/3. The plateau mechanism is presented as a consequence of narrow-band spectral cancellation, while the value R=4/3R=4/3R=4/3 is treated more conservatively as a minimal effective-weight assignment consistent with pulse-sequence symmetry and the numerical results. The revised manuscript also makes the falsifiability structure more explicit and narrows the scope of the numerical claims: the simulations support the existence and robustness of the plateau, but are not presented as a unique microscopic derivation of the effective channel weights. Note (updated): This record corresponds to an earlier exploratory version of the idea. Parts of the theoretical interpretation presented here were not fully established and have been refined in subsequent work. In particular, the universal interpretation of ratio plateaus should be treated with caution. Readers are encouraged to consult the later work (see related records) for a more robust and conservative formulation of the effective description.
This work presents a structural reformulation of quantum dynamics based on a scalar coherence functional defined over a general state space. The framework distinguishes two mathematically natural classes of dynamics generated by such a functional:(i) gradient flows, which monotonically increase coherence and correspond to stabilization or selection processes, and(ii) antisymmetric flows, which conserve coherence and generate reversible dynamics. We show that standard unitary quantum mechanics arises as a special case when the state space is a complex Hilbert space, the coherence functional is chosen as the negative energy expectation, and the antisymmetric structure corresponds to the canonical complex structure. In this setting, the Schrödinger equation follows directly from the formalism, without postulating unitarity as an independent axiom. The framework is extended to open systems using the density-operator formalism and completely positive trace-preserving maps. Under standard assumptions (Markovianity, continuity, and semigroup structure), the reduced dynamics takes the Gorini–Kossakowski–Sudarshan–Lindblad form, with dissipative terms interpreted as coherence-stabilizing dynamics. A supporting lemma demonstrates exponential suppression of off-diagonal density matrix elements under dephasing Lindblad operators. Using the Wigner phase-space representation, we further show that conservative coherence dynamics reduces to classical Liouville transport in the semiclassical regime, with quantum corrections governed by the Moyal bracket expansion. This work does not propose a modification of quantum theory. Rather, it offers a structural reorganization of existing formalisms. All results remain fully compatible with standard quantum mechanics while providing a unified perspective on unitary evolution, decoherence, and the emergence of classical behavior. Related work. A companion technical note, Structural Decomposition of SRG Recursion into Flow, Phase, and Closure (Halldórsson & ChatGPT, 2025, Zenodo), develops a discrete dynamical-systems formulation of SRG-style recursion and connects it explicitly to Lemmas 2.5, 2.7, and 2.9 of the present work.
Paper 14 develops the quantitative coherence dynamics that follow from the representational framework introduced in Papers 11–13 of The Articulation of Postulate P1. Building on the dissipative generator formulated in Paper 12 and the coherence‑regime structure of Paper 13, this work derives explicit dynamical equations for the bandwidth function c(t). These equations yield closed‑form expressions for coherence drift, decoherence timescales, tunneling corrections, and finite‑time coherence boundaries. The results provide the first operational bridge between Level‑1 representational dynamics and experimentally accessible Level‑2 behaviour. The framework predicts measurable deviations from standard quantum mechanics in regimes where c(t) varies appreciably, including drift‑induced decoherence, coherence‑dependent tunneling suppression, and horizon‑like loss of representability. Paper 14 therefore completes the transition from conceptual reinterpretation to quantitative prediction, preparing the ground for the experimental proposal developed in Paper 15.
Abstract Quantum decoherence, conventionally modeled as a stochastic process, remains the primary obstacle to scalable quantum computation. In this work, a conceptual framework grounded in the hydrodynamic formulation of quantum mechanics (Madelung-Bohm formalism) is presented, which reinterprets decoherence as a process governed by deterministic flow dynamics rather than fundamental randomness. A comprehensive numerical simulation of a qubit coupled to an environmental oscillator at strong coupling ( c = 1.5) has been performed, from which an ensemble of Bohmian trajectories has been extracted and analyzed. The strong coupling regime ensures conclusive, unambiguous demonstration of complete decoherence within accessible simulation times, with system purity exhibiting clear, monotonic decay from a pure to a maximally mixed state without residual oscillations. The results provide direct visualization of decoherence as a continuous dynamical evolution while perfectly reproducing the statistical predictions of standard open quantum systems theory, including Born rule agreement and decoherence-induced pointer state formation. The key finding is that the environmental influence—the ‘decoherence force’ F dec = − ∇ Q derived from the quantum potential—possesses a deterministic, non-random structure with identifiable spectral signatures. This insight provides the theoretical foundation for a class of Noise-Informed Control Strategies . It is argued that by experimentally characterizing this deterministic signature via quantum noise spectroscopy, bespoke control protocols can be designed to suppress or manipulate decoherence. This work shifts the perspective from combating fundamentally random noise to controlling a structured, deterministic interaction, aligning with emerging paradigms in quantum error correction and the information-selection principles of quantum Darwinism.
We demonstrate the existence of a universal, structurally unavoidable non-Markovian correction to effective exponential decay laws in open physical systems. The result is derived without assuming any fundamental dynamics, background time, spacetime structure, or microscopic model. The correction emerges solely from three generic ingredients: (i) the non-closure of correlational descriptions, (ii) projection to observable subsystems with unavoidable information loss, and (iii) spectral truncation of the induced structural operator. Under these minimal and representation-independent conditions, any effective exponential decay is necessarily accompanied by a long-time algebraic correction of the form P(t)∼e−γt(1+α/t+O(t−2)), with a fixed exponent and sign that cannot be removed without violating structural consistency. This result is independent of gravity, cosmology, and specific microscopic dynamics, and applies generically to quantum-coherent, weakly dissipative regimes commonly described by Markovian semigroup models. The prediction provides a direct, experimentally testable signature distinguishing strictly Markovian descriptions from structurally non-closed correlational frameworks.