Superfluidity and Chaos in low dimensional circuits

TL;DR

This paper investigates superfluidity in low-dimensional circuits, revealing that chaos plays a crucial role in determining superfluid behavior and identifying new chaotic vortex states beyond traditional criteria.

Contribution

It demonstrates that conventional Landau and Bogoliubov criteria fail in low-dimensional systems and introduces chaos as a key factor in superfluidity, uncovering novel chaotic vortex states.

Findings

Superfluidity criteria fail in low-dimensional circuits.

Chaos influences the stability of vortex states.

New types of superfluid states linked to chaos are identified.

Abstract

The hallmark of superfluidity is the appearance of "vortex states" carrying a quantized metastable circulating current. Considering a unidirectional flow of particles in a ring, at first it appears that any amount of scattering will randomize the velocity, as in the Drude model, and eventually the ergodic steady state will be characterized by a vanishingly small fluctuating current. However, Landau and followers have shown that this is not always the case. If elementary excitations (e.g. phonons) have higher velocity than that of the flow, simple kinematic considerations imply metastability of the vortex state: the energy of the motion cannot dissipate into phonons. On the other hand if this Landau criterion is violated the circulating current can decay. Below we show that the standard Landau and Bogoliubov superfluidity criteria fail in low-dimensional circuits. Proper determination of the superfluidity regime-diagram must account for the crucial role of chaos, an ingredient missing from the conventional stability analysis. Accordingly, we find novel types of superfluidity, associated with irregular or chaotic or breathing vortex states.