Speaker: Tilman Enss (Institute for Theoretical Physics, Heidelberg)

Title of Talk: Quantum anomaly and scaling dynamics in the 2D Fermi gas

Abstract:  A scale invariant system looks similar on different length scales. Usually this is realized only after some fine tuning, for instance near a phase transition or a scattering resonance. Remarkably, a classical gas in two dimensions is scale invariant for an arbitrary strength of contact interaction. This has striking consequences for its nonequilibrium scaling dynamics, in particular the breathing motion in a harmonic trapping potential [1]. For a two-dimensional fermionic quantum gas, instead, quantum fluctuations violate the classical scaling symmetry and give rise to a quantum anomaly. I will discuss the consequences of this scale anomaly and how it can be observed in the equation of state [2], the pairing properties [3], and the nonequilibrium scaling dynamics. [1] Pitaevskii and Rosch, Phys. Rev. A 55, R853 (1997). [2] Bauer, Parish and Enss, Phys. Rev. Lett. 112, 135302 (2014); Boettcher et al., Phys. Rev. Lett. 116, 045303 (2016). [3] Murthy et al., Science 359, 452 (2018).