A synthetic monopole source of Kalb-Ramond field in diamond

TL;DR

This paper reports the first detection of a tensor monopole in a solid-state system, synthesized via a 4D parameter space in diamond, characterized by its topological charge and Kalb-Ramond field, inspired by string theory.

Contribution

It demonstrates the creation and characterization of a tensor monopole in a solid-state defect, bridging condensed matter physics and string theory concepts.

Findings

Successful synthesis of a tensor monopole in diamond.

Measurement of its quantized topological charge.

Observation of spectral transitions under symmetry breaking.

Abstract

Magnetic monopoles play a central role in various areas of fundamental physics, ranging from electromagnetism to topological states of matter. While their observation is elusive in high-energy physics, monopole sources of artificial gauge fields have been recently identified in synthetic matter. String theory, a potentially unifying framework that encompasses quantum mechanics, promotes the conventional \emph{vector} gauge fields of electrodynamics to \emph{tensor} gauge fields, and predicts the existence of more exotic \emph{tensor monopoles} in 4D space. Here we report on the characterization of a tensor monopole synthesized in a 4D parameter space by the spin degrees of freedom of a single solid-state defect in diamond. Using two complementary methods, we characterize the tensor monopole by measuring its quantized topological charge and its emanating Kalb-Ramond field. By introducing a fictitious external field that breaks chiral symmetry, we further observe an intriguing transition in the spectrum, characterized by spectral rings protected by mirror symmetries. Our work represents the first detection of tensor monopoles in a solid-state system and opens up the possibility of emulating exotic topological structures inspired by string theory.