Non-Local Order in Elongated Dipolar Gases


  Jonathan Ruhman  ,  Emanuele G. Dalla-Torre  ,  Ehud Altman  
Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel

An elongated dipolar gas can undergo a structural instability from a linear to a zigzag configuration when the interaction energy overcomes the confining potential. Naively this entails breaking of Z2 symmetry. However, quantum fluctuations in the particle positions along the condensate can continuously deform the zigzag structure thus restoring the Z2 symmetry. By taking the proper continuum limit, we show that the Zigzag nevertheless survives as a well defined topological phase, characterized by a non local order parameter.