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Spread complexity in saddle-dominated scrambling

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arxiv 2312.12593 v3 pith:GGL5IFJT submitted 2023-12-19 hep-th nlin.CDquant-ph

classification hep-thnlin.CDquant-ph
keywords complexityspreadsystemsquantumsaddle-dominatedscramblingemphkrylov
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Recently, the concept of spread complexity, Krylov complexity for states, has been introduced as a measure of the complexity and chaoticity of quantum systems. In this paper, we study the spread complexity of the thermofield double state within \emph{integrable} systems that exhibit saddle-dominated scrambling. Specifically, we focus on the Lipkin-Meshkov-Glick model and the inverted harmonic oscillator as representative examples of quantum mechanical systems featuring saddle-dominated scrambling. Applying the Lanczos algorithm, our numerical investigation reveals that the spread complexity in these systems exhibits features reminiscent of \emph{chaotic} systems, displaying a distinctive ramp-peak-slope-plateau pattern. Our results indicate that, although spread complexity serves as a valuable probe, accurately diagnosing true quantum chaos generally necessitates additional physical input. We also explore the relationship between spread complexity, the spectral form factor, and the transition probability within the Krylov space. We provide analytical confirmation of our numerical results, validating the Ehrenfest theorem of complexity and identifying a distinct quadratic behavior in the early-time regime of spread complexity.

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Cited by 10 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

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    Anomalous initial states in otherwise thermalizing models leave compact, stationary low-depth Krylov-space cores—regions with persistent fluctuations, Gibbs mismatch, and current activity—while generic states do not.

  3. Brickwall One-Loop Determinant: Spectral Statistics & Krylov Complexity

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    In the brickwall model of a BTZ black hole, hand-tuned Gaussian randomness at a stretched horizon reproduces random-matrix-theory spectral statistics and Krylov complexity peaks for scalar and fermionic probes.

  4. Krylov Complexity in Mixed Phase Space

    hep-th 2024-12 conditional novelty 6.0 of 10

    The Krylov complexity peak height correlates with the Brody parameter in mixed-phase-space quantum systems, diminishing as the spectrum becomes Poissonian.

  5. Krylov Complexity in the Schr\"odinger Field Theory

    hep-th 2024-11 reject novelty 6.0 of 10

    For bosonic and fermionic Schrödinger fields with chemical potential μ≤0, the Lanczos coefficients grow linearly and the Krylov complexity grows exponentially with an extracted rate near 2.75/β, below the 4/β slope pr...

  6. Quasinormal modes and complexity in saddle-dominated SU(N) spin systems

    hep-th 2025-06 conditional novelty 5.0 of 10

    A family of SU(2) and SU(3) Lipkin-Meshkov-Glick-type Hamiltonians reproduces de Sitter quasinormal-mode densities of states, and late-time probes reveal integrability beneath saddle-dominated scrambling.

  7. Higher-Order Krylov State Complexity in Random Matrix Quenches

    hep-th 2024-12 conditional novelty 5.0 of 10

    Higher-order generalized spread complexities show a more pronounced pre-equilibration peak than standard spread complexity in random matrix quenches, quantifying chaos more sharply up to third order.

  8. Statistics and Complexity of Wavefunction Spreading in Quantum Dynamical Systems

    quant-ph 2024-11 conditional novelty 5.0 of 10

    The moments of the spreading-operator measurement distribution are generalized spread complexities, which for GUE Hamiltonians peak more sharply at higher order and obey a norm bound.

  9. Krylov Complexity and $c$-function along RG Flows

    hep-th 2026-08 conditional novelty 4.0 of 10

    Along holographic RG flows, the acceleration of spread complexity and the covariant c-function are algebraically related: inversely in fixed-dimension domain walls and Dp-branes, co-monotonically in twisted compactifications.

  10. Revisit the relationship between spread complexity rate and radial momentum

    hep-th 2024-11 conditional novelty 3.0 of 10

    The paper shows that two proposed bulk momentum and boundary spread complexity correspondences are consistent, and that the match extends to any particle mass in AdS3.

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