arXiv subjects

Parsa Kafashi

Publications and source records attributed to Parsa Kafashi.

3 recordsLinked to original sources

arXiv2026

Krylov Complexity for Time-Dependent Hamiltonians

We investigate Krylov spread complexity for states evolving under time-dependent Hamiltonians. For periodically driven systems, we formulate the problem within Floquet theory and show how the Magnus expansion provides a systematic approximation when the Floquet Hamiltonian is not available in closed form. We then extend this framework beyond periodic driving and demonstrate that, in addition to the globally truncated Magnus expansion, a piecewise Magnus expansion provides a reliable method when the global expansion loses convergence or accuracy. Our results provide practical tools for analyzing complexity growth in a broad class of time-dependent quantum systems.

hep-th↗

arXiv2025

Quantum-Inspired Approach to Analyzing Complex System Dynamics

We present a quantum information-inspired framework for analyzing complex systems through multivariate time series. In this approach the system's state is encoded into a density matrix, providing a compact representation of higher-order correlations and dependencies. This formulation enables precise quantification of the relative influence among time series, tracking of their response to external perturbations and also the definition of a recovery timescale without need for dimensional reduction. By leveraging tools such as fidelity from quantum information theory, our method naturally captures higher-order co-fluctuations beyond pairwise statistics, offering a holistic characterization of resilience and similarity in high-dimensional dynamics. We validate this approach on synthetic data generated by a 9-dimensional modified Lorenz-96 model and demonstrate its utility on real-world climate data, analyzing global temperature anomalies across nine regions, quantifying the dissimilarity of each 288-month time window up to July 2025 relative to the 1850-1874 baseline period.

nlin.CD↗

arXiv2025

Fast radio bursts as cosmic lightning

We propose a new model for the origin of Fast Radio Bursts (FRBs), attributing these phenomena to sudden discharges of accumulated electric charge in the accretion disk of compact objects such as black holes. Our framework demonstrates how Compton scattering within the disk plasma generates charge separation, creating a capacitor-like system stabilized by the equilibrium between radiation pressure and electrostatic forces. We detail the discharge process through destabilizing mechanisms in this capacitor, resulting in radiative emission. We compare our model's prediction on radiation signatures with observational data, using FRB2018725A as an example to obtain key quantitative relationships. Additionally, we estimate the total charge buildup via Compton scattering for a stellar-mass black hole, constrained by the best-fit between our model and observations, and determine the corresponding electron density in the accretion disk for this mechanism to operate.

astro-ph.HE↗