Comment on ``Nonlinear band structure in Bose-Einstein condensates: Nonlinear Schödinger equation with a Kronig Penney potential"

Abstract

In their recent paper [Phys. Rev. A 71, 033622], B. T. Seaman et al. studied Bloch states of the condensate wave function in a Kronig-Penney potential and calculated the band structure. They argued that the effective mass is always positive when a swallow-tail energy loop is present in the band structure. In this comment, we reexamine their argument by actually calculating the effective mass. It is found that there exists a region where the effective mass is negative even when a swallow-tail is present. Based on this fact, we discuss the interpretation of swallow-tails in terms of superfluidity.

3 pages, 3 figures

References in corpus (6)

• Superfluidity and Swallowtails; Hysteretic Behavior in Bose Condensates
• Loop structure of the lowest Bloch band for a Bose-Einstein condensate
• Superfluid Dynamics of a Bose-Einstein Condensate in a Periodic Potential
• Nonlinear Band Structure in Bose Einstein Condensates: The Nonlinear Schrödinger Equation with a Kronig-Penney Potential
• Period doubling, two-color lattices, and the growth of swallowtails in Bose-Einstein condensates
• Stability of Bose-Einstein condensates in a Kronig-Penney potential