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20232026
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hep-th2026

Stochastic Krylov Dynamics: Revisiting Operator Growth in Open Quantum Systems

Arpan Bhattacharyya, S. Shajidul Haque, Jeff Murugan +2

In closed quantum systems, Krylov complexity admits a geometric description; operator growth is equivalent to Hamiltonian flow in an emergent phase space whose structure is fixed b…

hep-th2025

Inflation is Not Magic

S. Shajidul Haque, Ghadir Jafari, Bret Underwood

Cosmological perturbations generated during inflation exhibit striking quantum features, including entanglement and high circuit complexity. Yet their observational signatures rema…

hep-th2024

Universal Early-Time Growth in Quantum Circuit Complexity

S. Shajidul Haque, Ghadir Jafari, Bret Underwood

We show that quantum circuit complexity for the unitary time evolution operator of any time-independent Hamiltonian is bounded by linear growth at early times, independent of any c…

hep-th2024

The Early Universe as an Open Quantum System: Complexity and Decoherence

Arpan Bhattacharyya, Suddhasattwa Brahma, S. Shajidul Haque +2

In this work, we extend previous results, demonstrating how complexity in an open quantum system can identify decoherence between two fields, even in the presence of an acceleratin…

hep-th2023

Complexity and Operator Growth for Quantum Systems in Dynamic Equilibrium

Cameron Beetar, Nitin Gupta, S. Shajidul Haque +2

Krylov complexity is a measure of operator growth in quantum systems, based on the number of orthogonal basis vectors needed to approximate the time evolution of an operator. In th…