Experimental realization of a Dirac monopole through the decay of an isolated monopole

TL;DR

This paper reports the experimental observation of how isolated monopoles in spin-1 Bose-Einstein condensates decay into configurations containing Dirac monopoles, revealing detailed dynamics and the influence of magnetic field gradients.

Contribution

It presents the first experimental realization and detailed characterization of the decay process of isolated monopoles into Dirac monopoles in quantum gases.

Findings

Decay dynamics depend on magnetic field gradients

Spontaneous nodal lines emerge during decay

Dirac monopoles are characterized via spin density measurements

Abstract

We experimentally observe the decay dynamics of deterministically created isolated monopoles in spin-1 Bose-Einstein condensates. As the condensate undergoes a change between magnetic phases, the isolated monopole gradually evolves into a spin configuration hosting a Dirac monopole in its synthetic magnetic field. We characterize in detail the Dirac monopole by measuring the particle densities of the spin states projected along different quantization axes. Importantly, we observe the spontaneous emergence of nodal lines in the condensate density that accompany the Dirac monopole. We also demonstrate that the monopole decay accelerates in weaker magnetic field gradients.