1. PROPOSED TITLE OF THE WORKSHOP "Gauge Theories and Fractionalization in Correlated Quantum Matter" 2. PROPOSED ORGANIZERS M. Franz (UBC), Assistant Professor 604-222-4974 A. Vishwanath (Berkeley), Assistant Professor 617-253-2895 D.A. Bonn (UBC), Professor bonn@physics.ubc.ca 604-822-1997 O. Tchernyshyov (Johns Hopkins), Assistant Professor 410-516-8586 M. Randeria (Tata Institute/Ohio State U.), Professor (91)-22-2280-4545 Xiao Gang Wen (MIT), Professor 617-253-5016 3. PROPOSED TIME Prefered: July 10 - August 12 Acceptable: June, July, August Impossible: May, September Proposed length: 5 weeks Availability of the Organizers: Franz 3-4 weeeks Vishwanath 3-4 weeks Bonn 2-3 weeks Tchernyshyov 3-4 weeks Randeria 3-4 weeks Potential timing conflicts with another meeting: -we are not aware of any at this time. 4. CONTACT PERSON AVAILABLE FOR CONSULTATION A. Vishwanath (ashvinv@mit.edu) 5. PERSON RESPONSIBLE FOR WORKING TO ENSURE DIVERSITY O. Tchernyshyov (olegt@pha.jhu.edu) 6. DESCRIPTION AND JUSTIFICATION OF THE PROPOSED WORKSHOP One of the central achievements of condensed matter physics is the Fermi liquid paradigm whereby a vast number of electronic systems are described in terms of phases where the excitations carry the quantum numbers of the electron (or finite groups of electrons). However, more recently a variety of experimental systems have been discovered whose properties seem to depart in fundamental ways from this paradigm. These include the high temperature cuprate superconductors, several rare earth intermetallics (heavy fermions) at a quantum critical point as well as some two dimensional quantum magnets (eg. Cs_2CuCl_4, k-ET_2Cu_2(CN)_3). These "non-Fermi liquid" systems now represent a new frontier in the condensed matter physics. One attractive route to realizing non-Fermi liquid phases is via quantum number fractionalization - i.e. phases where the excitations carry quantum numbers that are a fraction of the electrons quantum numbers. While there exist well studied theoretical and experimental systems where this phenomenon occurs in one dimensional and quantum hall effect systems, one is forced to think of higher dimensional realizations of the same phenomenon with time reversal symmetry, in order to construct models of some of the systems described above. Our theoretical understanding of this type of fractionalization has enormously increased over the last few years, and one of the central observations is that all known realizations of this phenomenon rely on the emergence of a gauge theory in its deconfined phase. The proposed workshop will focus on gauge theories of condensed matter systems and their role in understanding exotic non-Fermi liquid states of correlated electron matter. In condensed matter physics, gauge fields do not represent fundamental forces; instead they emerge in the low energy sector of theories describing strongly interacting many-particle systems. Often, such emergent gauge structures provide the only means of describing the interactions in terms of local fields. Such local theories are then accessible to standard field theoretic techniques and provide crucial insights into the physics of correlated quantum matter. Important past examples where gauge theories played crucial roles in understanding paradigm-shifting phenomena include the fractional quantum Hall effect, one-dimensional interacting systems, quantum magnets and exotic superconductors. These systems also provide concrete experimental realizations of new concepts such as topological field theories, fractionalized quantum numbers, topological order and phase transitions and exotic particle statistics, which in turn influenced various other areas of physics and mathematics. In the recent years gauge theories in condensed matter gained further prominence and widespread use. They have led to exciting new developments on several fronts. It is safe to say that wherever the real action is in contemporary condensed matter physics, gauge fields are involved. Among the most prominent such efforts are descriptions of frustrated classical and quantum spin systems, theories of disordered and glassy media, generalizations of fractional quantum Hall effect to higher dimensions, quantum criticality in heavy fermion systems, models of high-temperature superconductors, cold atom condensates in optical lattices, and momentum space gauge structures in quantum spintronics. One inherent advantage of condensed matter systems is that experimental tests of the predictions of these theories can be much more easily performed than, for example, in particle physics. Indeed, specific experiments were proposed (and carried out) to test for the manifestations of specific emergent gauge structures in cuprate superconductors and other correlated systems. The outcomes of these experiments proved to be of great importance for the condensed mater physics and could also be viewed as table-top tests for ideas relevant to particle physics and cosmology where direct experiments are often hard to come by. We now have a small number of microscpic models that display the phenomenon of fractionalization, and we would like to understand better the conditions under which such physics is likely to occur, which will provide a useful guide to evaluating which experimental systems are more likely to be fractionlized. In this workshop we intend to focus on the following topics: - Microscopic models leading to fractionalized phases - Experimental Signatures of Fractionalized Phases - Theoretical issues (classification, stability) - Fractionalization and Topological Quantum Computing - Cold Atom Realizations of Fractionalized phases 7. PROSPECTIVE PARTICIPANTS We envision a workshop organized around the "gauge principle" and its applications to condensed matter systems. We hope to have several prominent condensed matter theorists in attendance from all the main areas listed above, along with some prominent high-energy theorists. We also plan to invite small number of knowledgeable condensed matter experimentalists working in these areas to provide a reality check. We have conducted an informal e-mail survey among ~50 top workers in these areas to gauge their interest in a workshop of this kind. We received 46 responses, almost all supportive and many enthusiastic. We attach below the list of people who expressed strong interest and are likely to attend. By any standard this is a truly stellar group of prospective participants representing broad spectrum of interests. We take this high level of interest from an elite group of scientists as a strong indication of timeliness, relevance and importance of the proposed topic. ***Theorists: Dung-Hai Lee Steve Kivelson Bob Laughlin Philip Anderson Matthew Fisher Antonio Castro Neto Senthil Todadri Subir Sachdev Hae-Young Kee Eduardo Fradkin Shivaji Sondhi Patrick Lee Xiao-Gang Wen Naoto Nagaosa Andrew Millis Eugene Demler Sudip Chakravarty Chetan Nayak Zlatko Tesanovic Ian Affleck Joel Moore Igor Herbut Asle Sudbo Brad Marston Roderich Moessner Thierry Giamarchi Lev Ioffe Alexei Kitaev Nick Read Steve Girvin Michael Freedman Grigori Volovik Shuichi Murakami Cliff Burgess V.P.Nair Frank Wilczek Paul Wiegmann Andreas Ludwig R.Shankar Assa Auerbach Jan Zaanen Jianping Hu Sasha Balatsky Mike Norman Catherine Kallin , Andrey Chubukov Doug Scalapino Leonid Pryadko Chandra Varma Sandro Sorella Andrei Marie Tremblay Fei Zhou Paul Fendley Claire Lhuillier Masaki Oshikawa Steve Simon ***Experimentalists: Doug Bonn Berhard Keimer Juan C. Campuzano Z. X. Shen N. Phuan Ong J. C. Seamus Davis Gabriel Aeppli Louis Taillefer Robert Birgeneau Kathryn Moler Radu Coldea Bill Buyers Pengcheng Dai Art Ramirez