The International Workshop "Supersolidity 2011" (to be held at the Graduate Center of City University of New York, June 7-10, 2011) is devoted to one of the most exciting discoveries in solid state physics in the last decade -- possible long-sought supersolid state of matter in free space. The discovery has spawned an explosion of both experimental and theoretical studies clearly indicating that the quantum solid He4 is richer in new phenomena than ever imagined. This workshop will provide an exciting timely opportunity for the US and international community of scientists -- young and established -- to learn and exchange ideas on the latest developments around the world in order to unravel the enigma of supersolidity in solid He4 and other systems. Direct cross-communications create synergy in understanding the phenomena in a very efficient way and play a crucial role in resolving the main theoretical and experimental challenges in the field of supersolidity. As an essential part of the education and training in natural sciences, the support from the National Science Foundation will allow active participation of young US scientists in this exciting process.
This award has supported the International Workshop "Supersolids 2011" devoted to studying the nature of one of the most exciting discoveries in condensed matter physics in the last several years --- so called torsional oscillator anomaly in solid Helium-4 observed by Kim and Chan at Penn State University in 2004. This anomaly possibly indicates that solid Helium-4 is actually a supersolid , that is, a new quantum state of matter which simultaneously exhibits properties of a solid and a fluid which has no viscosity --- superfluid. Theoretically, such state was proposed by several prominent theoreticians --- Andreev and Lifshitz, Thouless, Chester and Leggett --- more than 40 years ago. The discovery of Kim and Chan published in Nature and Science in 2004 has initiated an explosion of both experimental and theoretical studies of this peculiar quantum solid state. This workshop took place at the Graduate Center of City University of New York, June 7-10, 2011. It continued the sequence of similar meetings which took place in Santa Barbara, Japan, France, Italy and Canada. It has attracted leading researchers with complimentary expertise – in experiment and theory. Young researchers -- graduate students and postdoctoral fellows -- have also actively participated in lively discussions as speakers and presenters of posters. There were 27 young researchers (among the total of 57 participants). For all of them the registration fee was forfeited. Twenty three have asked for the travel and lodging support. Eleven of them have been supported from this NSF grant (and others --- through other sources). Direct cross-communications between scientists with various backgrounds and expertise has created synergy in better understanding of the phenomena in a very efficient way and played a crucial role in addressing the main theoretical and experimental challenges in the field of supersolidity. This workshop has presented an opportunity for active discussions of several conflicting views on the nature of the effect. Nobel Laureate P.W. Anderson has presented new arguments in favor of his radical view that all solids consisting of bosonic particles must be supresolids at very low temperature. There were also advocates of the belief that Kim's and Chan's anomaly can be explained in terms of so called two-level systems normally observed in glasses, and there is no need to invoke the idea of supersolid. The results of state of the art first principle computer simulations of solid Helium-4 have also been presented. They clearly demonstrated that supersolidity can only exist along structural defects of the solid --- dislocations and grain boundaries. The report of a direct superflow through solid Helium (R. Hallock, University of Massachusetts in Amherst ) provides strong support for this purely numerical discovery. More details about the participants and their talks can be found on the website http://mcwa.csi.cuny.edu/supersolid/. An important event included into the workshop program was the public lecture given by S. Balibar from Ecole Normale Superieure, Paris. He has explained the nature of the phenomenon of superfluidity in Helium-4 and Helium-3 and has also discussed the history and researchers involved in their discoveries. Supersolidity of Helium-4 was presented as the very interesting and promising development in the field of quantum fluids and solids. We strongly believe that this workshop and the public lecture have stimulated more interest in Condensed Matter Physics among the general public and, especially, among students.
