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Variational Neural Quantum Statesfor the one-dimensional TransverseField Ising Model: Variationsbaserade neurala kvanttillstånd för den endi-mensionella Transverse Field Ising modellen
Karlstad University.
2026 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

The Transverse Field Ising Model (TFIM) is an important quantum many-body model used to study the competition between spin-spin interactions and quantum fluctuations generated by a transverse field. Due to the exponential growth of the Hilbert space with increasing system size, numerical methods quickly become computationally infeasible motivating the use of approximate approaches. In this work Neural Quantum States were used as a variational method to approximate the ground-state properties of the one-dimensional TFIM. The NQS was represented using a feedforward Neural Network and optimized through Monte Carlo sampling together with stochastic reconfiguration. The implementation was done through the NetKet framework. The obtained results showed stable convergence of the variational energy and good agreement with exact diagonalization for the smaller system. The quantum phase transition was observed through the order parameter  and spin-spin correlations. Finite-size effects were also observed when comparing the two system sizes. The smaller system more closely approaches the symmetric cat-like ground-state. In contrast, the larger system tends to remain near one symmetry-broken configuration. As a result, the smaller system showed stronger spin expectation fluctuations and a smoother behavior near the phase transition.

The result demonstrates that the NQS approach is a good approximate method in studying the ground-state physics of the one-dimensional TFIM.

Place, publisher, year, edition, pages
2026. , p. 38
Keywords [en]
AI, TFIM, Ising Model, NQS, Neural Quantum States, Neural Network, NN
National Category
Physical Sciences Natural Sciences Condensed Matter Physics
Identifiers
URN: urn:nbn:se:kau:diva-110662OAI: oai:DiVA.org:kau-110662DiVA, id: diva2:2070954
Subject / course
Physics
Educational program
Engineering: Engineering Physics (300 ECTS credits)
Presentation
(English)
Supervisors
Examiners
Available from: 2026-08-25 Created: 2026-06-12 Last updated: 2026-08-25Bibliographically approved

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Physical SciencesNatural SciencesCondensed Matter Physics

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CiteExportLink to record
Permanent link

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Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
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