Anomalous Breaking of Scale Invariance in a Two-Dimensional Fermi Gas
- 17 September 2018
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 121 (12), 120401
- https://doi.org/10.1103/physrevlett.121.120401
Abstract
The frequency of the breathing mode of a two-dimensional Fermi gas with zero-range interactions in a harmonic confinement is fixed by the scale invariance of the Hamiltonian. Scale invariance is broken in the quantized theory by introducing the two-dimensional scattering length as a regulator. This is an example of a quantum anomaly in the field of ultracold atoms and leads to a shift of the frequency of the collective breathing mode of the cloud. In this work, we study this anomalous frequency shift for a two-component Fermi gas in the strongly interacting regime. We measure significant upwards shifts away from the scale-invariant result that show a strong interaction dependence. This observation implies that scale invariance is broken anomalously in the strongly interacting two-dimensional Fermi gas.Funding Information
- H2020 European Research Council (725636)
- Zentrum für Quantendynamik, Universität Heidelberg
- Deutsche Forschungsgemeinschaft
- Horizon 2020 Framework Programme (706487)
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