Scale Invariance in the Lowest Landau Level

We show that the discrete set of pair amplitudes $A_m$ introduced by Haldane are an angular-momentum resolved generalization of the Tan two-body contact, which parametrizes universal short-range correlations in atomic quantum gases. The pair amplitudes provide a complete description of translation-i...

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Main Authors: Hofmann, Johannes, Zwerger, Wilhelm
Format: Article
Language:English
Published: Académie des sciences 2023-06-01
Series:Comptes Rendus. Physique
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Online Access:https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.137/
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author Hofmann, Johannes
Zwerger, Wilhelm
author_facet Hofmann, Johannes
Zwerger, Wilhelm
author_sort Hofmann, Johannes
collection DOAJ
description We show that the discrete set of pair amplitudes $A_m$ introduced by Haldane are an angular-momentum resolved generalization of the Tan two-body contact, which parametrizes universal short-range correlations in atomic quantum gases. The pair amplitudes provide a complete description of translation-invariant and rotation-invariant states in the lowest Landau level (LLL), both compressible and incompressible. To leading nontrivial order beyond the non-interacting high-temperature limit, they are determined analytically in terms of the Haldane pseudopotential parameters $V_m$, which provides a qualitative description of the crossover towards incompressible ground states for different filling factors. Moreover, we show that for contact interactions $\sim g_2 \delta ^{(2)}(\mathbf{x})$, which are scale invariant at the classical level, the non-commutativity of the guiding center coordinates gives rise to a quantum anomaly in the commutator $i [\hat{H}_{\mathrm{LLL}}, \hat{D}_R] = (2 + \ell \partial _\ell ) \hat{H}_{\mathrm{LLL}}$ with the dilatation operator $\hat{D}_R$ in the LLL, which replaces the trace anomaly in the absence of a magnetic field. The interaction-induced breaking of scale invariance gives rise to a finite frequency shift of the breathing mode in a harmonic trap, which describes transitions between different Landau levels, the strength of which is estimated in terms of the relevant dimensionless coupling constant $\tilde{g}_2$.
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spelling doaj-art-48e6afaed0e2420aa2f2e33e554387a72025-02-07T13:53:11ZengAcadémie des sciencesComptes Rendus. Physique1878-15352023-06-0124S3698610.5802/crphys.13710.5802/crphys.137Scale Invariance in the Lowest Landau LevelHofmann, Johannes0Zwerger, Wilhelm1Department of Physics, Gothenburg University, 41296 Gothenburg, SwedenTechnische Universität München, Physik Department, James-Franck-Strasse, 85748 Garching, GermanyWe show that the discrete set of pair amplitudes $A_m$ introduced by Haldane are an angular-momentum resolved generalization of the Tan two-body contact, which parametrizes universal short-range correlations in atomic quantum gases. The pair amplitudes provide a complete description of translation-invariant and rotation-invariant states in the lowest Landau level (LLL), both compressible and incompressible. To leading nontrivial order beyond the non-interacting high-temperature limit, they are determined analytically in terms of the Haldane pseudopotential parameters $V_m$, which provides a qualitative description of the crossover towards incompressible ground states for different filling factors. Moreover, we show that for contact interactions $\sim g_2 \delta ^{(2)}(\mathbf{x})$, which are scale invariant at the classical level, the non-commutativity of the guiding center coordinates gives rise to a quantum anomaly in the commutator $i [\hat{H}_{\mathrm{LLL}}, \hat{D}_R] = (2 + \ell \partial _\ell ) \hat{H}_{\mathrm{LLL}}$ with the dilatation operator $\hat{D}_R$ in the LLL, which replaces the trace anomaly in the absence of a magnetic field. The interaction-induced breaking of scale invariance gives rise to a finite frequency shift of the breathing mode in a harmonic trap, which describes transitions between different Landau levels, the strength of which is estimated in terms of the relevant dimensionless coupling constant $\tilde{g}_2$.https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.137/Bose–Einstein condensates under rapid rotationLowest Landau LevelVirial ExpansionScale invariance and quantum scale anomalyUniversal/exact (Tan) relations
spellingShingle Hofmann, Johannes
Zwerger, Wilhelm
Scale Invariance in the Lowest Landau Level
Comptes Rendus. Physique
Bose–Einstein condensates under rapid rotation
Lowest Landau Level
Virial Expansion
Scale invariance and quantum scale anomaly
Universal/exact (Tan) relations
title Scale Invariance in the Lowest Landau Level
title_full Scale Invariance in the Lowest Landau Level
title_fullStr Scale Invariance in the Lowest Landau Level
title_full_unstemmed Scale Invariance in the Lowest Landau Level
title_short Scale Invariance in the Lowest Landau Level
title_sort scale invariance in the lowest landau level
topic Bose–Einstein condensates under rapid rotation
Lowest Landau Level
Virial Expansion
Scale invariance and quantum scale anomaly
Universal/exact (Tan) relations
url https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.137/
work_keys_str_mv AT hofmannjohannes scaleinvarianceinthelowestlandaulevel
AT zwergerwilhelm scaleinvarianceinthelowestlandaulevel