Exotic Order and Criticality in Quantum Matter

Coordinators: Leon Balents, Sankar Das Sarma, Subir Sachdev, Shivaji Sondhi, Matthias Troyer

Experimental puzzles are mounting in a panoply of materials, from frustrated magnets to high-T$_c$ superconductors to semiconductor heterostructures. Motivated in part by these experiments, theorists in recent years have proposed a wealth of novel suggestions of organization of strongly interacting quantum condensed matter which do not fit the standard paradigms of solid state and statistical physics. These include "order from disorder" in frustrated quantum magnets, non-bosonic quantum criticality, dualities, spin-charge separation, fractionalization and topological order, and exotic condensates with associated quantized topological defects. Very recently, certain such phenomena have been argued to be beneficial for applications to quantum computing. The exploration of these ideas is still in its infancy, and this program will bring together scientists to put them on a fully-developed theoretical and contextual footing.

Rather than attacking "from the bottom up" a small set of topical material systems, this program will take the "top down" approach of focusing on qualitatively new concepts. Once the character of a hypothetical phenomena is understood, we will devise experimental signatures to detect it in a variety of physical systems, and identify those candidates for which it is most likely. This will include the systems mentioned above, as well as others such as quantum Hall "stripe" and bilayer phases, spinor and rotating atom Bose gases, and low-dimensional conductors such as carbon nanotubes.