Identification of Quantum Spin Liquids via Symmetry-Protected Quantum Criticality

A quantum spin liquid (QSL) is one of the most entangled states of many-body systems whose identification is known to be notoriously difficult in experiments. Any spontaneously broken symmetries are absent, and experimental investigations based on symmetry are commonly believed to be inapplicable. Here, we demonstrate that a class of QSLs may be identified by using symmetry-protected quantum criticality induced by external fields such as electromagnetic fields and strains. Specifically, we show that QSLs with symmetry-protected quantum criticality, including Dirac quantum spin liquids, may be controlled by the external fields. We also discuss distinctive experimental signatures of QSLs with symmetry-protected quantum criticality.