Observation of scale invariance in two-dimensional matter-wave Townes solitons

TL;DR

This paper demonstrates the near-deterministic creation of 2D matter-wave Townes solitons and provides a precise experimental test of their scale invariance, confirming theoretical predictions across various interaction strengths.

Contribution

It presents the first experimental observation of scale invariance in 2D matter-wave solitons and tests the universality of Townes soliton profiles under different interaction conditions.

Findings

Confirmed collapse of density profiles onto a single curve when rescaled

Observed universal Townes soliton profiles across different coupling constants

Demonstrated that magnetic dipole-dipole interactions conform to the same scaling law

Abstract

We report near-deterministic generation of two-dimensional (2D) matter-wave Townes solitons, and a precision test on scale invariance in attractive 2D Boses gases. We induce a shape-controlled modulational instability in an elongated 2D matter-wave to create an array of isolated solitary waves of various sizes and peak densities. We confirm scale invariance by observing the collapse of solitary-wave density profiles onto a single curve in a dimensionless coordinate rescaled according to their peak densities, and observe that the scale-invariant profiles measured at different coupling constants $g$ can further collapse onto the universal profile of Townes solitons. The reported scaling behavior is tested with a nearly 60-fold difference in soliton interaction energies, and allows us to discuss the impact of a non-negligible magnetic dipole-dipole interaction (MDDI) on 2D scale invariance. We confirm that the effect of MDDI in our alkali cesium quasi-2D samples effectively conforms to the same scaling law governed by a contact interaction to well within our experiment uncertainty.