Abstract: | A quantum spin liquid is a state of matter with strong spin correlations over short distances, but in which quantum fluctuations and geometrical frustration impede the formation of long-range order, leading instead to a fluid-like state over long distances. Although the experimental detection of such a state has remained elusive, the potential payoff for its observation is great, with rich physical consequences such as fractional particles and emergent gauge fields. Recently, a host of promising new materials has been discovered which may provide the first experimental examples of spin liquids. I will discuss recent experimental and theoretical developments in this field. |