Nous montrons que l’ensemble discret des amplitudes de paires introduit par Haldane est une généralisation résolue en moment cinétique du coefficient de contact à deux corps de Tan, qui paramétrise les corrélations universelles à courte distance dans les gaz quantiques atomiques. Les amplitudes de paires fournissent une description complète des états invariants par translation et par rotation dans le niveau de Landau fondamental (LLL), qu’ils soient compressibles ou incompressibles. Au premier ordre non nul au-delà de la limite de haute température sans interaction, elles sont déterminées analytiquement en fonction des paramètres du pseudopotentiel de Haldane, ce qui fournit une description qualitative du passage vers des états fondamentaux incompressibles pour différents taux de remplissage. De plus, nous montrons que pour les interactions de contact , qui sont invariantes d’échelle au niveau classique, la non-commutation des coordonnées du centre de giration donne naissance à une anomalie quantique dans le commutateur de l’hamiltonien avec le générateur des dilatations dans le LLL, qui remplace l’anomalie de Weyl sur la trace en l’absence de champ magnétique. La brisure de l’invariance d’échelle induite par l’interaction conduit à un déplacement de fréquence du mode de respiration dans un piège harmonique, qui reflète des transitions entre différents niveaux de Landau et dont nous estimons la valeur en termes de la constante de couplage sans dimension pertinente .
We show that the discrete set of pair amplitudes 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 , which provides a qualitative description of the crossover towards incompressible ground states for different filling factors. Moreover, we show that for contact interactions , 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 with the dilatation operator 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 .
@article{CRPHYS_2023__24_S3_A5_0, author = {Johannes Hofmann and Wilhelm Zwerger}, title = {Scale {Invariance} in the {Lowest} {Landau} {Level}}, journal = {Comptes Rendus. Physique}, publisher = {Acad\'emie des sciences, Paris}, year = {2023}, doi = {10.5802/crphys.137}, language = {en}, note = {Online first}, }
Johannes Hofmann; Wilhelm Zwerger. Scale Invariance in the Lowest Landau Level. Comptes Rendus. Physique, Online first (2023), pp. 1-18. doi : 10.5802/crphys.137.
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