Superfluid tunneling

We study inter-well coherent quantum tunneling of Bose-Einstein condensates (BEC's) in optical lattices. Irrespective of whether the BEC is a superfluid in the whole lattice, it may or may not be a superfluid within each well of the lattice depending on whether the ratio of the well kinetic energy to the interaction energy is small or large. When the bosons in each well are superfluid, we have Josephson tunneling among the wells driven by the phase difference between the superfluids in the different wells. For typical lattice parameters the Josephson tunneling rate will be somewhat enhanced from the naive estimate of (tunneling energy scale) $/\hbar$ . Whether it is enhanced or not will depend on lattice parameters, but it can never be zero. When the bosons in each well are not superfluid, there is coherent quantum tunneling of essentially free bosons between the wells. This tunneling is proportional to the boson number difference between the wells.We study inter-well coherent quantum tunneling of Bose-Einstein condensates (BEC's) in optical lattices. Irrespective of whether the BEC is a superfluid in the whole lattice, it may or may not be a superfluid within each well of the lattice depending on whether the ratio of the well kinetic energy to the interaction energy is small or large. When the bosons in each well are superfluid, we have Josephson tunneling among the wells driven by the phase difference between the superfluids in the different wells. For typical lattice parameters the Josephson tunneling rate will be somewhat enhanced from the naive estimate of (tunneling energy scale)$/\hbar$. Whether it is enhanced or not will depend on lattice parameters, but it can never be zero. When the bosons in each well are not superfluid, there is coherent quantum tunneling of essentially free bosons between the wells. This tunneling is proportional to the boson number difference between the wells.

arXiv:cond-mat/0312417Dec 17, 20030 citations

Tunnelling of topological line defects in strongly coupled superfluids

Uwe R. Fischer

The geometric theory of vortex tunnelling in superfluid liquids is developed. Geometry rules the tunnelling process in the approximation of an incompressible superfluid, which yields the identity of phase and configuration space in the vortex collective co-ordinate. To exemplify the implications of this approach to tunnelling, we solve explicitly for the two-dimensional motion of a point vortex in the presence of an ellipse, showing that the hydrodynamic collective co-ordinate description limits the constant energy paths allowed for the vortex in configuration space. We outline the experimental procedure used in helium II to observe tunnelling events, and compare the conclusions we draw to the experimental results obtained so far. Tunnelling in Fermi superfluids is discussed, where it is assumed that the low energy quasiparticle excitations localised in the vortex core govern the vortex dynamical equations. The tunnelling process can be dominated by Hall or dissipative terms, respectively be under the influence of both, with a possible realization of this last intermediate case in unconventional, high-temperature superconductors.The geometric theory of vortex tunnelling in superfluid liquids is developed. Geometry rules the tunnelling process in the approximation of an incompressible superfluid, which yields the identity of phase and configuration space in the vortex collective co-ordinate. To exemplify the implications of this approach to tunnelling, we solve explicitly for the two-dimensional motion of a point vortex in the presence of an ellipse, showing that the hydrodynamic collective co-ordinate description limits the constant energy paths allowed for the vortex in configuration space. We outline the experimental procedure used in helium II to observe tunnelling events, and compare the conclusions we draw to the experimental results obtained so far. Tunnelling in Fermi superfluids is discussed, where it is assumed that the low energy quasiparticle excitations localised in the vortex core govern the vortex dynamical equations. The tunnelling process can be dominated by Hall or dissipative terms, respectively be under the influence of both, with a possible realization of this last intermediate case in unconventional, high-temperature superconductors.

arXiv:cond-mat/9909166Annalen der PhysikJul 1, 20002 citations

Tunnelling of topological line defects in strongly coupled superfluids

Uwe R. Fischer

Abstract The geometric theory of vortex tunnelling in superfluid liquids is developed. Geometry rules the tunnelling process in the approximation of an incompressible superfluid, which yields the identity of phase and configuration space in the vortex collective co‐ordinate. To exemplify the implications of this approach to tunnelling, we solve explicitly for the two‐dimensional motion of a point vortex in the presence of an ellipse, showing that the hydrodynamic collective co‐ordinate description limits the constant energy paths allowed for the vortex in configuration space. We outline the experimental procedure used in helium II to observe tunnelling events, and compare the conclusions we draw to the experimental results obtained so far. Tunnelling in Fermi superfluids is discussed, where it is assumed that the low energy quasiparticle excitations localised in the vortex core govern the vortex dynamical equations. The tunnelling process can be dominated by Hall or dissipative terms, respectively be under the influence of both, with a possible realization of this last intermediate case in unconventional, high‐temperature superconductors.Abstract The geometric theory of vortex tunnelling in superfluid liquids is developed. Geometry rules the tunnelling process in the approximation of an incompressible superfluid, which yields the identity of phase and configuration space in the vortex collective co‐ordinate. To exemplify the implications of this approach to tunnelling, we solve explicitly for the two‐dimensional motion of a point vortex in the presence of an ellipse, showing that the hydrodynamic collective co‐ordinate description limits the constant energy paths allowed for the vortex in configuration space. We outline the experimental procedure used in helium II to observe tunnelling events, and compare the conclusions we draw to the experimental results obtained so far. Tunnelling in Fermi superfluids is discussed, where it is assumed that the low energy quasiparticle excitations localised in the vortex core govern the vortex dynamical equations. The tunnelling process can be dominated by Hall or dissipative terms, respectively be under the influence of both, with a possible realization of this last intermediate case in unconventional, high‐temperature superconductors.

Annalen der PhysikJul 1, 20001 citation

/\hbar

. Whether it is enhanced or not will depend on lattice parameters, but it can never be zero. When the bosons in each well are not superfluid, there is coherent quantum tunneling of essentially free bosons between the wells. This tunneling is proportional to the boson number difference between the wells.