Temporal shaping and time varying orbital angular momentum of displaced vortices

TL;DR

This paper analytically explores the complex, time-varying dynamics of displaced vortices in 2D quantum fluids, revealing phenomena like oscillating orbital angular momentum and vortex morphology reshaping, with implications for controlling angular momentum in light and quantum systems.

Contribution

It introduces a comprehensive analytical study of displaced vortices exhibiting dynamic orbital angular momentum and morphology changes, extending recent phenomenology to fundamental 2D quantum fluid systems.

Findings

Displaced vortices show self-sustained oscillations of OAM.

Vortex morphology can reshape with vortex-antivortex pair creation.

Vortex cores can undergo complex trajectories, including acceleration and return.

Abstract

The fundamental mode of rotation in quantum fluids is given by a vortex, whose quantized value yields the orbital angular momentum (OAM) per particle. If the vortex is displaced (off-centered) from the reference point for rotation, the angular momentum is reduced and becomes fractional. Such displaced vortices can further exhibit a peculiar dynamics in presence of confining potentials or couplings to other fields. We study analytically a number of 2D systems where displaced vortices exhibit a noteworthy dynamics, including time-varying self-sustained oscillation of the OAM, complex reshaping of their morphology with possible creation of vortex-antivortex pairs and peculiar trajectories for the vortex core with sequences of strong accelerations and decelerations which can even send the core to infinity and bring it back. Interestingly, these do not have to occur conjointly, with complex time dynamics of the vortex core and/or their wavepacket morphology possibly taking place without affecting the total OAM. Our results generalize to simple and fundamental systems a phenomenology recently reported with Rabi-coupled bosonic fields, showing their wider relevance and opening prospects for new types of control and structuring of the angular momentum of light and/or quantum fluids.