Spread and Spectral Complexity in Quantum Spin Chains: from Integrability to Chaos

Fuente: arXiv
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Main Authors: Camargo, Hugo A., Huh, Kyoung-Bum, Jahnke, Viktor, Jeong, Hyun-Sik, Kim, Keun-Young, Nishida, Mitsuhiro
Format: Preprint
Published: 2024
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author Camargo, Hugo A.
Huh, Kyoung-Bum
Jahnke, Viktor
Jeong, Hyun-Sik
Kim, Keun-Young
Nishida, Mitsuhiro
author_facet Camargo, Hugo A.
Huh, Kyoung-Bum
Jahnke, Viktor
Jeong, Hyun-Sik
Kim, Keun-Young
Nishida, Mitsuhiro
contents We explore spread and spectral complexity in quantum systems that exhibit a transition from integrability to chaos, namely the mixed-field Ising model and the next-to-nearest-neighbor deformation of the Heisenberg XXZ spin chain. We corroborate the observation that the presence of a peak in spread complexity before its saturation, is a characteristic feature in chaotic systems. We find that, in general, the saturation value of spread complexity post-peak depends not only on the spectral statistics of the Hamiltonian, but also on the specific state. However, there appears to be a maximal universal bound determined by the symmetries and dimension of the Hamiltonian, which is realized by the thermofield double state (TFD) at infinite temperature. We also find that the time scales at which the spread complexity and spectral form factor change their behaviour agree with each other and are independent of the chaotic properties of the systems. In the case of spectral complexity, we identify that the key factor determining its saturation value and timescale in chaotic systems is given by minimum energy difference in the theory's spectrum. This explains observations made in the literature regarding its earlier saturation in chaotic systems compared to their integrable counterparts. We conclude by discussing the properties of the TFD which, we conjecture, make it suitable for probing signatures of chaos in quantum many-body systems.
format Preprint
id arxiv_https___arxiv_org_abs_2405_11254
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Spread and Spectral Complexity in Quantum Spin Chains: from Integrability to Chaos
Camargo, Hugo A.
Huh, Kyoung-Bum
Jahnke, Viktor
Jeong, Hyun-Sik
Kim, Keun-Young
Nishida, Mitsuhiro
High Energy Physics - Theory
Statistical Mechanics
Chaotic Dynamics
Quantum Physics
We explore spread and spectral complexity in quantum systems that exhibit a transition from integrability to chaos, namely the mixed-field Ising model and the next-to-nearest-neighbor deformation of the Heisenberg XXZ spin chain. We corroborate the observation that the presence of a peak in spread complexity before its saturation, is a characteristic feature in chaotic systems. We find that, in general, the saturation value of spread complexity post-peak depends not only on the spectral statistics of the Hamiltonian, but also on the specific state. However, there appears to be a maximal universal bound determined by the symmetries and dimension of the Hamiltonian, which is realized by the thermofield double state (TFD) at infinite temperature. We also find that the time scales at which the spread complexity and spectral form factor change their behaviour agree with each other and are independent of the chaotic properties of the systems. In the case of spectral complexity, we identify that the key factor determining its saturation value and timescale in chaotic systems is given by minimum energy difference in the theory's spectrum. This explains observations made in the literature regarding its earlier saturation in chaotic systems compared to their integrable counterparts. We conclude by discussing the properties of the TFD which, we conjecture, make it suitable for probing signatures of chaos in quantum many-body systems.
title Spread and Spectral Complexity in Quantum Spin Chains: from Integrability to Chaos
topic High Energy Physics - Theory
Statistical Mechanics
Chaotic Dynamics
Quantum Physics
url https://arxiv.org/abs/2405.11254