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Cover Figure

COVER When rotated above a critical frequency, a single quantum of circulation, known as a vortex, forms in a gaseous Bose-Einstein condensate, marking the breakdown of superfluidity in a quantum fluid. The vortex core appears in this absorption image of the rubidium atom cloud as a hole in the density profile. The Gordon Research Conference on Atomic Physics will meet at Williams College on 17 to 22 June. The summer and international conference schedules begin on p. 1569.

 [Image: Kirk W. Madison, Frédéric Chevy, Jean Dalibard/Laboratoire Kastler Brossel, École Normale Supérieure, Paris]