Recognition: no theorem link
Precision-Induced Irreversibility in non-Hermitian systems
Pith reviewed 2026-05-15 00:30 UTC · model grok-4.3
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.
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
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.
Referee Report
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)
- [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.
- [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)
- 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
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
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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
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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
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
free parameters (1)
- resolution floor
axioms (2)
- standard math Non-Hermitian evolution is mathematically invertible
- domain assumption Non-normality produces amplification and mode mixing
invented entities (1)
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Precision-Induced Irreversibility (PIR)
no independent evidence
Reference graph
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Precision-Induced Irreversibility in non-Hermitian systems
G. Pappas, D. Bautista Avil ´es, L. E. F. Foa Torres, and V . Achilleos, Universal critical timescales in slow non-Hermitian dynamics, arXiv:2604.01918 (2026). A.3 Non-Hermitian Systems: Amplification Creates Vulnerability 7 Supplementary Information for: “Precision-Induced Irreversibility in non-Hermitian systems” A. WHY PIR IS FUNDAMENTALLY NON-HERMITIA...
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Summary: Three-Way Comparison Table S1 summarizes the key differences between the three classes of systems. The central message is that non-Hermiticity alone (middle column) does not cause PIR; mode mixing is the essential additional ingredient. Moreover, normality (which warrants mode mixing) is highly nongeneric in complex non-Hermitian systems [1]. Wit...
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[41]
Derivation of the Propagator The propagatorU(t) =e −iHt can be computed exactly using the Cayley-Hamilton theorem. For a2×2matrix, any analytic functionf(H)can be written asf(H) =αI+βHwhere the coefficients are determined by the eigenvaluesλ ± =±iηwith η= p γ2 −g 2. Solving for the coefficients frome −iλ±t =α±β(iη), we obtain: U(t) = cosh(ηt)I− i η sinh(η...
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[42]
Singular Value Decomposition The condition numberκ(U) =σ max/σmin requires the singular values, which are the square roots of the eigenvalues ofU†U. ComputingU †Uand using the identitycosh 2 −sinh 2 = 1, we find after algebraic simplification that the eigenvalues ofU †U take the remarkably simple form: µ± = p 1 +y(t) 2 ±y(t) 2 ,(S15) where we have defined...
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[43]
Exact Condition Number Formula The condition number follows immediately: κ(U)(t) = σ+ σ− = p 1 +y(t) 2 +y(t) 2 = exp(2 asinh(y(t))) (S17) This exact result, valid for allt≥0, has several important properties: •Correct initial condition:Att= 0,y(0) = 0givesκ(U)(0) = 1exactly, as required for the identity propagator. •Smooth crossover:The formula interpolat...
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[44]
The Geometric Prefactor and Its Physical Meaning The prefactorC= (γ/η) 2 has a geometric interpretation. Near an exceptional point (g→γ, soη→0), this prefactor diverges, reflecting the coalescence of eigenvectors. The relationship to the eigenvector condition numberκ(V)is: κ(V) = r γ+g γ−g = 1p 1−(g/γ) 2 · r 1 +g/γ 1 ,(S19) which gives: C= 1 1 +g/γ 2 κ(V)...
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[45]
Exact Overflow Time Settinglnκ(U)(T of) =mlnβ(the threshold condition) and inverting Eq. (S17): T (exact) of = 2 ∆b asinh η γ sinh mlnβ 2 (S21) This exact formula has the correct limits: • Form→0:T of →0(no precision means immediate overflow). • For largem: Usingasinh(x)≈ln(2x)forx≫1: Tof ≈ mlnβ−lnC ∆b = mlnβ ∆b − 2 ln(γ/η) ∆b .(S22) The geometric correct...
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[46]
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...
work page 2026
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[47]
Prepare an ensemble of different initial states{|ψ (j) 0 ⟩}
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[48]
For each, measureη W (τ)across a range of evolution times
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[49]
Verify that: • Pre-Tof valuesη rev,(j) W differ across preparations • Post-Tof behavior converges to a common asymptotic regime The collapse of initial-state dependence atT of is the unambiguous signature of information evaporation: the system has genuinely “forgotten” which state it started from. E.5. Comparison with Fidelity The fidelityF(τ) =|⟨ψ 0|ψrec...
work page 2005
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