On the Mathematical Theory of Superfluidity

We provide a general operator algebraic formulation of superfluidity in Bose systems, with the aim of investigating the relationships of this phenomenon both to off-diagonal long range order (ODLRO) and to a mathematically precise version of Landau's picture of elementary excitations. Our principal results are that ODLRO leads both to rotational superfluidity and to Goldstone excitations, while the neo-Landau picture accounts for the translational superfluidity of flow along a pipe. The latter picture is realised by the Lieb-Liniger-Girardeau model. Open problems are briefly discussed.