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arxiv: 2603.22284 · v2 · submitted 2026-03-23 · 🪐 quant-ph · cond-mat.stat-mech

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Precision-Induced Irreversibility in non-Hermitian systems

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Pith reviewed 2026-05-15 00:30 UTC · model grok-4.3

classification 🪐 quant-ph cond-mat.stat-mech
keywords non-Hermitian systemsirreversibilityprecisionpredictability horizonnon-normalityecho fidelityquantum dynamicsmode mixing
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The pith

Finite precision creates an irreversible predictability horizon in non-Hermitian systems even without decoherence.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

Non-Hermitian evolution is mathematically invertible, yet the paper shows that amplification, non-normality-induced mode mixing, and any finite resolution floor together produce a sharp operational limit called the predictability horizon T_of. Beyond this time, distinct initial states map to identical observed representations. The mechanism operates inside the effective non-Hermitian description alone; removing amplification, mode mixing, or the resolution limit restores reversibility. This matters for any physical or numerical implementation where gain or loss is present, because it sets a concrete bound on how far dynamics can be reversed.

Core claim

We identify Precision-Induced Irreversibility (PIR): amplification, mode mixing (as warranted by non-normality), and a finite resolution floor -- whether set by numerical precision, detector noise, or environmental fluctuations -- conspire to produce a quantitative predictability horizon T_of, beyond which distinct states collapse onto identical representations. Within the effective non-Hermitian description, the mechanism requires neither environmental decoherence nor nonlinear dynamics; remove any ingredient and reversibility can be restored. Echo-fidelity tests confirm this transition across arbitrary-precision arithmetic and hardware, revealing where formal invertibility and physical or,

What carries the argument

Precision-Induced Irreversibility (PIR), the interaction of amplification and non-normality-driven mode mixing with a finite resolution floor that produces the predictability horizon T_of.

Load-bearing premise

The effective non-Hermitian description captures the dynamics without requiring explicit environmental decoherence or nonlinear terms.

What would settle it

An experiment or simulation in which echo fidelity stays high past the calculated T_of despite controlled amplification and finite resolution would falsify the claim.

Figures

Figures reproduced from arXiv: 2603.22284 by D. Bautista Avil\'es, G. Pappas, Luis E. F. Foa Torres, V. Achilleos.

Figure 1
Figure 1. Figure 1: The dynamic-range crisis and predictability horizon. (a) Under non-Hermitian evolution, the amplified mode |cp(t)| (red) grows while suppressed mode |cq(t)| (blue) decays exponentially, driving dynamic range ratio r(t) = |cp|/|cq| across orders of mag￾nitude. The shaded area (precision shadow) marks the relative pre￾cision threshold ε · |cp(t)| below which the subdominant component becomes numerically unre… view at source ↗
Figure 2
Figure 2. Figure 2: Sharp-knee signatures of precision-induced reversibil￾ity breakdown. (a) Loschmidt-echo fidelity F(t) for precision val￾ues m ∈ {15, 50, 90} bits using mpmath with time step ∆t = 0.4. Sharp transition at Tof separates reversible (F ≈ 1) from irre￾versible (F ≪ 1) regimes. Vertical dashed lines mark predicted Tof = m ln(β)/∆b with ∆b = 1.327 (time in units of 1/g). (b) Work-echo ratio ηW (t) for the same pr… view at source ↗
Figure 3
Figure 3. Figure 3: Universal scaling of overflow time with precision. Initial state |ψ0⟩ = (1, 0)T ; Tof is initial-state independent. Main panel: Overflow time Tof versus precision bits m, measured via Loschmidt fidelity F (circles) and work-echo ratio ηW (crosses) using onset de￾tection (1% deviation from reversible plateau). Data from arbitrary￾precision stepped evolution (mpmath, orange) and native hardware arithmetic (f… view at source ↗
read the original abstract

Non-Hermitian evolution is mathematically invertible, yet finite dynamic range imposes a sharp operational limit on reversibility. We identify Precision-Induced Irreversibility (PIR): amplification, mode mixing (as warranted by non-normality), and a finite resolution floor -- whether set by numerical precision, detector noise, or environmental fluctuations -- conspire to produce a quantitative predictability horizon $T_{\mathrm{of}}$, beyond which distinct states collapse onto identical representations. Within the effective non-Hermitian description, the mechanism requires neither environmental decoherence nor nonlinear dynamics; remove any ingredient and reversibility can be restored. Echo-fidelity tests confirm this transition across arbitrary-precision arithmetic and hardware, revealing where formal invertibility and physical reversibility diverge.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The manuscript proposes Precision-Induced Irreversibility (PIR) as a mechanism in non-Hermitian systems whereby amplification, non-normal mode mixing, and a finite resolution floor (from numerical precision, detector noise, or fluctuations) together generate a quantitative predictability horizon T_of beyond which distinct states become indistinguishable. The authors assert that this occurs within the effective non-Hermitian dynamics alone, without requiring decoherence or nonlinearity, and is confirmed by echo-fidelity tests across precisions.

Significance. If the central mechanism is placed on a quantitative footing, the result would be significant for non-Hermitian quantum mechanics and open-system simulations: it supplies an intrinsic, precision-based route to effective irreversibility that is independent of environmental coupling, potentially explaining limits on reversibility in PT-symmetric or gain-loss systems and guiding precision requirements in quantum control protocols.

major comments (2)
  1. [Abstract] Abstract: the claim that amplification + non-normality + resolution floor produces a 'quantitative predictability horizon T_of' is not supported by any explicit scaling relation or inequality bounding T_of in terms of the non-normality measure (e.g., condition number), transient growth factor, or resolution floor; the transition is asserted rather than derived.
  2. [Echo-fidelity tests] Echo-fidelity tests: the confirmatory numerical tests are invoked without a protocol specifying the model Hamiltonian, how the resolution floor is implemented, the precise definition of echo fidelity, or how T_of is extracted from the fidelity drop, preventing verification that the horizon depends only on the stated ingredients.
minor comments (1)
  1. The notation T_of is introduced without an explicit definition or functional dependence on the resolution parameter; a short equation or scaling expression would improve clarity.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive comments on our manuscript. The points raised have helped us improve the quantitative rigor and reproducibility of the Precision-Induced Irreversibility mechanism. We address each major comment below and have revised the manuscript accordingly.

read point-by-point responses
  1. Referee: [Abstract] Abstract: the claim that amplification + non-normality + resolution floor produces a 'quantitative predictability horizon T_of' is not supported by any explicit scaling relation or inequality bounding T_of in terms of the non-normality measure (e.g., condition number), transient growth factor, or resolution floor; the transition is asserted rather than derived.

    Authors: We agree that the abstract would be strengthened by an explicit relation. In the revised manuscript we have added a derivation (new subsection II.B) showing that the predictability horizon obeys the bound T_of ≥ ln(1/ε) / ln(κ), where κ is the condition number of the non-normal generator and ε is the resolution floor. The bound follows from the transient-growth estimate ||e^{At}|| ≤ κ exp(α t) together with the requirement that the amplified separation between nearby states drops below ε. The abstract has been updated to reference this scaling, and the numerical results are now compared against the analytic expression. revision: yes

  2. Referee: [Echo-fidelity tests] Echo-fidelity tests: the confirmatory numerical tests are invoked without a protocol specifying the model Hamiltonian, how the resolution floor is implemented, the precise definition of echo fidelity, or how T_of is extracted from the fidelity drop, preventing verification that the horizon depends only on the stated ingredients.

    Authors: We thank the referee for highlighting the missing protocol details. The revised 'Numerical verification' section now specifies: (i) the explicit 2×2 non-Hermitian Hamiltonian H = [[-i, 2], [0, -i]] used throughout, (ii) the resolution floor implemented by rounding each component of the state vector to a fixed number of significant digits (ε = 10^{-d}) after every time step, (iii) echo fidelity defined as F(t) = |⟨ψ(0)|U†(-t)U(t)|ψ(0)⟩|^2 with U(t) = exp(-iHt), and (iv) T_of extracted as the first time at which F(t) falls below 0.5. The full simulation code and parameter files have been added as supplementary material to enable independent verification. revision: yes

Circularity Check

0 steps flagged

No circularity: mechanism described from standard non-Hermitian properties plus external resolution floor, confirmed by tests without self-referential reduction

full rationale

The paper defines Precision-Induced Irreversibility (PIR) as the joint effect of amplification, non-normality-driven mode mixing, and an externally supplied finite resolution floor (numerical precision, detector noise, or fluctuations) that produces a predictability horizon T_of. Echo-fidelity tests are invoked to confirm the transition, but no derivation chain, equation, or fitted parameter is shown that defines T_of in terms of itself or renames a fit as a prediction. No self-citation load-bearing uniqueness theorems, ansatzes smuggled via prior work, or self-definitional steps appear. The resolution floor is explicitly treated as an independent input whose removal restores reversibility, keeping the argument non-circular and externally falsifiable via the stated tests.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 1 invented entities

The claim rests on the standard mathematical property that non-Hermitian evolution is invertible, the domain assumption that non-normality produces amplification and mode mixing, and the newly introduced concept of PIR whose quantitative horizon depends on an unspecified resolution floor.

free parameters (1)
  • resolution floor
    Finite limit set by numerical precision, detector noise, or fluctuations that determines when states become indistinguishable; no fitting procedure or value is given in the abstract.
axioms (2)
  • standard math Non-Hermitian evolution is mathematically invertible
    Explicitly stated as the baseline before finite-resolution effects are introduced.
  • domain assumption Non-normality produces amplification and mode mixing
    Invoked to explain how small differences grow until they hit the resolution floor.
invented entities (1)
  • Precision-Induced Irreversibility (PIR) no independent evidence
    purpose: To label the mechanism that converts mathematical invertibility into operational irreversibility via finite resolution
    Newly coined term whose independent evidence is limited to the echo-fidelity tests described in the abstract.

pith-pipeline@v0.9.0 · 5434 in / 1607 out tokens · 49144 ms · 2026-05-15T00:30:36.522388+00:00 · methodology

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Reference graph

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    Numerical Verification Table S3 compares the exact analytical predictions with numerical simulations for the parameters used in the main text. The excellent agreement supports that the exact analytical solution accurately describes the PIR phenomenon. D.3. Stepped Evolution with Fractional Steps To evolve to an arbitrary target timeτ, we decompose: τ=N fu...

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    Prepare an ensemble of different initial states{|ψ (j) 0 ⟩}

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    forgotten

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