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We investigate the role of a statistical complexity measure to assign equilibration in isolated quantum systems. While unitary dynamics preserve global purity, expectation values of observables often exhibit equilibration-like behavior,…

Quantum Physics · Physics 2025-08-14 Marcos G. Alpino , Tiago Debarba , Reinaldo O. Vianna , André T. Cesário

We extend the CV conjecture to quantum states of two-mode Hermitian systems using the framework of information geometry. Specifically, we conjecture that the Krylov complexity of a quantum state equals the volume of the Fubini-Study metric.…

High Energy Physics - Theory · Physics 2026-05-22 Ke-Hong Zhai , Lei-Hua Liu , Hai-Qing Zhang

We study the dynamics of correlations in a paradigmatic setup to observe $\mathcal{PT}$-symmetric physics: a pair of coupled oscillators, one subject to a gain one to a loss. Starting from a coherent state, quantum correlations (QCs) are…

We investigate Krylov spread complexity for the ground state of two-band Hamiltonians, where the reference state is a generic state on the Bloch sphere. The spread complexity is obtained by using a purely geometric formulation in terms of…

Quantum Physics · Physics 2026-05-19 Rishav Chaudhuri , Ayush Raj , Soham Ray , Sai Satyam Samal

Many quantum gravitational frameworks, such as DBI inflation, k-essence, and effective field theories obtained by integrating out heavy modes, can lead to a non-trivial sound speed. Meanwhile, our universe can be described as an open…

General Relativity and Quantum Cosmology · Physics 2026-02-27 Shi-Cheng Liu , Lei-Hua Liu , Bichu Li , Hai-Qing Zhang , Peng-Zhang He

We present an iterative generalisation of the quantum subspace expansion algorithm used with a Krylov basis. The iterative construction connects a sequence of subspaces via their lowest energy states. Diagonalising a Hamiltonian in a given…

Quantum Physics · Physics 2025-05-07 Tom O'Leary , Lewis W. Anderson , Dieter Jaksch , Martin Kiffner

In this work, we investigate the relation between different notions of quantum complexity, namely, circuit and spread complexity and physically meaningful quantities such as the particle content of the quantum state and the variances of…

Quantum Physics · Physics 2025-11-05 Satyaki Chowdhury

We study the synchronization of a generalized Kuramoto system in which the coupling weights are determined by the phase differences between oscillators. We employ the fast-learning regime in a Hebbian-like plasticity rule so that the…

Analysis of PDEs · Mathematics 2021-06-29 Jinyeong Park , David Poyato , Juan Soler

We investigate minimal two-body Hamiltonians with random interactions that generate spectra resembling those of Gaussian random matrices, a phenomenon we term quadratic quantum chaos. Unlike integrable two-body fermionic systems, the…

High Energy Physics - Theory · Physics 2026-04-16 Pallab Basu , Suman Das , Pratik Nandy

Operator growth, or operator spreading, describes the process where a "simple" operator acquires increasing complexity under the Heisenberg time evolution of a chaotic dynamics, therefore has been a key concept in the study of quantum chaos…

Statistical Mechanics · Physics 2021-11-18 Laimei Nie

The operator fidelity is a measure of the information-theoretic distinguishability between perturbed and unperturbed evolutions. The response of this measure to the perturbation may be formulated in terms of the operator fidelity…

Quantum Physics · Physics 2011-01-20 N. Tobias Jacobson , Paolo Giorda , Paolo Zanardi

We continue the analysis of the Krylov complexity in the IP matrix model. In a previous paper, for a fundamental operator, it was shown that at zero temperature, the Krylov complexity oscillates and does not grow, but in the infinite…

High Energy Physics - Theory · Physics 2023-08-17 Norihiro Iizuka , Mitsuhiro Nishida

Classical quasi-integrable systems are known to have Lyapunov times much shorter than their ergodicity time -- the most clear example being the Solar System -- but the situation for their quantum counterparts is less well understood. As a…

Quantum Physics · Physics 2020-09-02 Tomer Goldfriend , Jorge Kurchan

The Frimmer-Novotny model to simulate two-level systems by coupled oscillators is extended by incorporating a constant time delay in the coupling. The effects of the introduced delay on system dynamics and two-level modeling are then…

In this paper, we consider an $N$-oscillators complexified Kuramoto model. We first observe that there are solutions exhibiting finite-time blow-up behavior in all coupling regimes. When the coupling strength $\lambda>\lambda_c$, sufficient…

Dynamical Systems · Mathematics 2026-01-21 Ting-Yang Hsiao , Yun-Feng Lo , Winnie Wang

Krylov subspace methods in quantum dynamics identify the minimal subspace in which a process unfolds. To date, their use is restricted to time evolutions governed by time-independent generators. We introduce a generalization valid for…

Quantum Physics · Physics 2025-01-27 Kazutaka Takahashi , Adolfo del Campo

The Rosenbrock-Krylov family of time integration schemes is an extension of Rosenbrock-W methods that employs a specific Krylov based approximation of the linear system solutions arising within each stage of the integrator. This work…

Numerical Analysis · Mathematics 2019-10-08 Paul Tranquilli , Ross Glandon , Adrian Sandu

The harmonic oscillator is the paragon of physical models; conceptually and computationally simple, yet rich enough to teach us about physics on scales that span classical mechanics to quantum field theory. This multifaceted nature extends…

High Energy Physics - Theory · Physics 2021-02-10 Arpan Bhattacharyya , Wissam Chemissany , S. Shajidul Haque , Jeff Murugan , Bin Yan

The exponential growth of the out-of-time-ordered correlator (OTOC) has been proposed as a quantum signature of classical chaos. The growth rate is expected to coincide with the classical Lyapunov exponent. This quantum-classical…

The nonintegrable transverse-field Ising model is a common platform for studying ergodic quantum dynamics. In this work, we introduce a simple variant of the model in which this ergodic behaviour is suppressed by introducing a spatial…

Quantum Physics · Physics 2025-12-24 Gaurav Rudra Malik , Jeet Sharma , Rohit Kumar Shukla , S. Aravinda , Sunil Kumar Mishra