Comment on “Nonlinear band structure in Bose-Einstein condensates: Nonlinear Schrödinger equation with a Kronig-Penney potential”

Ippei Danshita and Shunji Tsuchiya
Phys. Rev. A 76, 017601 – Published 16 July 2007

Abstract

In their recent paper [Phys. Rev. A 71, 033622 (2005)], 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 swallowtail 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 swallowtail is present. Based on this fact, we discuss the interpretation of swallowtails in terms of superfluidity.

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  • Received 1 March 2007

DOI:https://doi.org/10.1103/PhysRevA.76.017601

©2007 American Physical Society

Authors & Affiliations

Ippei Danshita1,2,* and Shunji Tsuchiya3

  • 1National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
  • 2Department of Physics, Waseda University, 3-4-1 Ōkubo, Shinjuku, Tokyo 169-8555, Japan
  • 3Dipartimento di Fisica, Università di Trento and CNR-INFM BEC Center, I-38050 Povo, Italy

  • *danshita@nist.gov

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Vol. 76, Iss. 1 — July 2007

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