%ABroholm, C.%ACava, R.%AKivelson, S.%ANocera, D.%ANorman, M.%ASenthil, T.%Anull Ed.%BJournal Name: Science; Journal Volume: 367; Journal Issue: 6475 %D2020%I %JJournal Name: Science; Journal Volume: 367; Journal Issue: 6475 %K %MOSTI ID: 10216207 %PMedium: X %TQuantum spin liquids %XSpin liquids are quantum phases of matter with a variety of unusual features arising from their topological character, including “fractionalization”—elementary excitations that behave as fractions of an electron. Although there is not yet universally accepted experimental evidence that establishes that any single material has a spin liquid ground state, in the past few years a number of materials have been shown to exhibit distinctive properties that are expected of a quantum spin liquid. Here, we review theoretical and experimental progress in this area. %0Journal Article