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K-complexity and the Jordan-Wigner transformation

Krylov complexity is a measure of operator growth that demonstrates universal properties and bounds a large class of complexities. One such measure from this bounded class is operator size. The relationship between operator size and operator growth has been conjectured to be non-trivial due to the e...

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Main Author: Pandit, Zayd
Other Authors: Murugan, Jeffrey
Format: Thesis
Language:English
English
Published: Department of Mathematics and Applied Mathematics 2026
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access_status_str Open Access
author Pandit, Zayd
author2 Murugan, Jeffrey
author_browse Murugan, Jeffrey
Pandit, Zayd
author_facet Murugan, Jeffrey
Pandit, Zayd
author_sort Pandit, Zayd
collection Thesis
description Krylov complexity is a measure of operator growth that demonstrates universal properties and bounds a large class of complexities. One such measure from this bounded class is operator size. The relationship between operator size and operator growth has been conjectured to be non-trivial due to the existence of duality transformations such as the Jordan-Wigner (JW) transformation which map small operators to large, non-local operators. We investigate this claim directly in the case of the JW transformation which maps the XY Heisenberg chain to the Kitaev chain. We numerically calculate the complexity of dual operators, and analyse the early and late time behaviour and symmetries. We find that for Open Boundary Conditions (OBC) the early time behaviour of the K-Complexity correlates with operator size, but that large operators can have very low K-Complexity if dual to a small operator. We find that for Periodic Boundary Conditions (PBC) larger operators produce larger early time growth, but do not correlate to larger late-time complexity regardless of the size of the dual operator. The difference between the OBC and PBC results arise from an often overlooked break in translational symmetry across the PBC Jordan-Wigner transformation. We also find that state complexity is not sensitive to the break in translational symmetry.
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institution University of Cape Town (South Africa)
language English
eng
last_indexed 2026-06-10T12:32:05.102Z
license_str Not specified — see source repository
provenance_str_mv Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository
publishDate 2026
publishDateRange 2026
publishDateSort 2026
publisher Department of Mathematics and Applied Mathematics
publisherStr Department of Mathematics and Applied Mathematics
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source_str UCTD — University of Cape Town Open Access Repository
spelling oai:open.uct.ac.za:11427/42644 K-complexity and the Jordan-Wigner transformation Pandit, Zayd Murugan, Jeffrey Van Zyl, Hendrik Open Boundary Conditions Krylov complexity Krylov complexity is a measure of operator growth that demonstrates universal properties and bounds a large class of complexities. One such measure from this bounded class is operator size. The relationship between operator size and operator growth has been conjectured to be non-trivial due to the existence of duality transformations such as the Jordan-Wigner (JW) transformation which map small operators to large, non-local operators. We investigate this claim directly in the case of the JW transformation which maps the XY Heisenberg chain to the Kitaev chain. We numerically calculate the complexity of dual operators, and analyse the early and late time behaviour and symmetries. We find that for Open Boundary Conditions (OBC) the early time behaviour of the K-Complexity correlates with operator size, but that large operators can have very low K-Complexity if dual to a small operator. We find that for Periodic Boundary Conditions (PBC) larger operators produce larger early time growth, but do not correlate to larger late-time complexity regardless of the size of the dual operator. The difference between the OBC and PBC results arise from an often overlooked break in translational symmetry across the PBC Jordan-Wigner transformation. We also find that state complexity is not sensitive to the break in translational symmetry. 2026-01-21T13:06:18Z 2026-01-21T13:06:18Z 2025 2026-01-21T12:58:14Z Thesis / Dissertation Masters MSc http://hdl.handle.net/11427/42644 en eng application/pdf Department of Mathematics and Applied Mathematics Faculty of Science University of Cape Town
spellingShingle Open Boundary Conditions
Krylov complexity
Pandit, Zayd
K-complexity and the Jordan-Wigner transformation
thesis_degree_str Master's
title K-complexity and the Jordan-Wigner transformation
title_full K-complexity and the Jordan-Wigner transformation
title_fullStr K-complexity and the Jordan-Wigner transformation
title_full_unstemmed K-complexity and the Jordan-Wigner transformation
title_short K-complexity and the Jordan-Wigner transformation
title_sort k complexity and the jordan wigner transformation
topic Open Boundary Conditions
Krylov complexity
url http://hdl.handle.net/11427/42644
work_keys_str_mv AT panditzayd kcomplexityandthejordanwignertransformation