On Krylov complexity in open systems: an approach via bi-Lanczos algorithm

A Bhattacharya, P Nandy, PP Nath, H Sahu - Journal of High Energy …, 2023 - Springer
A bstract Continuing the previous initiatives [1, 2], we pursue the exploration of operator
growth and Krylov complexity in dissipative open quantum systems. In this paper, we resort …

Spread complexity and localization in -symmetric systems

A Bhattacharya, RN Das, B Dey, J Erdmenger - Physical Review B, 2024 - APS
We present a framework for investigating wave function spreading in PT-symmetric quantum
systems using spread complexity and spread entropy. We consider a tight-binding chain …

Krylov complexity for nonlocal spin chains

A Bhattacharya, PP Nath, H Sahu - Physical Review D, 2024 - APS
Building upon recent research in spin systems with nonlocal interactions, this study
investigates operator growth using the Krylov complexity in different nonlocal versions of the …

Spread complexity for measurement-induced non-unitary dynamics and Zeno effect

A Bhattacharya, RN Das, B Dey… - Journal of High Energy …, 2024 - Springer
A bstract Using spread complexity and spread entropy, we study non-unitary quantum
dynamics. For non-hermitian Hamiltonians, we extend the bi-Lanczos construction for the …

Probing Krylov complexity in scalar field theory with general temperatures

PZ He, HQ Zhang - Journal of High Energy Physics, 2024 - Springer
A bstract Krylov complexity characterizes the operator growth in the quantum many-body
systems or quantum field theories. The existing literatures have studied the Krylov …

Lyapunov exponent as a signature of dissipative many-body quantum chaos

AM García-García, JJM Verbaarschot, J Zheng - Physical Review D, 2024 - APS
A distinct feature of Hermitian quantum chaotic dynamics is the exponential increase of
certain out-of-time-order correlation (OTOC) functions around the Ehrenfest time with a rate …

Operator growth hypothesis in open quantum systems

NS Srivatsa, C von Keyserlingk - Physical Review B, 2024 - APS
The operator growth hypothesis (OGH) is a technical conjecture about the behavior of
operators—specifically, the asymptotic growth of their Lanczos coefficients—under repeated …

Spread complexity in saddle-dominated scrambling

KB Huh, HS Jeong, JF Pedraza - Journal of High Energy Physics, 2024 - Springer
A bstract 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 …

Krylov complexity is not a measure of distance between states or operators

SE Aguilar-Gutierrez, A Rolph - Physical Review D, 2024 - APS
We ask whether Krylov complexity is mutually compatible with the circuit and Nielsen
definitions of complexity. We show that the Krylov complexities between three states fail to …

Quantum Dynamics in Krylov Space: Methods and Applications

P Nandy, AS Matsoukas-Roubeas… - arxiv preprint arxiv …, 2024 - arxiv.org
The dynamics of quantum systems unfolds within a subspace of the state space or operator
space, known as the Krylov space. This review presents the use of Krylov subspace …