Quantum scale anomaly and spatial coherence in a 2D Fermi superfluid

Abstract:

Quantum anomalies are violations of classical scaling symmetries caused by divergences that appear in the quantization of certain classical theories. Although they play a prominent role in the quantum field theoretical description of many-body systems, their influence on experimental observables is difficult to discern. In this study, we discovered a distinctive manifestation of a quantum anomaly in the momentum-space dynamics of a two-dimensional (2D) Fermi superfluid of ultracold atoms. The measured pair momentum distributions of the superfluid during a breathing mode cycle exhibit a scaling violation in the strongly interacting regime. We found that the power-law exponents that characterize long-range phase correlations in the system are modified by the quantum anomaly, emphasizing the influence of this effect on the critical properties of 2D superfluids.

P. A. Murthy, N. Defenu, L. Bayha, M. Holten, P. M. Preiss, T. Enss und S. Jochim, „Quantum
scale anomaly and spatial coherence in a 2D Fermi superfluid“, Science 365, 268 (2019).

https://www.science.org/doi/10.1126/science.aau4402

Related to Project C01, C02, ABC