Relative Phase and Coherence in Bright Matter-Wave Solitons
T.P. Billam, D. Holdaway, S.A. Wrathmall, S.L. Cornish, and S.A. Gardiner
Funded by EPSRC Grant EP/G056781/1 and the Durham University Doctoral Fellowship Scheme
Bright matter-wave solitons are self-stabilizing, coherent aggregrations of ultracold bosonic atoms which exist in a near 1D configuration and are robust to collisions. They form from atomic Bose-Einstein condensates when the interatomic interactions are rapidly changed from repulsive to attractive. This process usually results in a violent collapse out of which several solitons spontaneously emerge. These solitons display a remarkable stability, and are generally assumed to be phase-coherent with one another. In addition to their fundamental interest, bright matter-wave solitons offer real advantages in matter-wave-based metrology, due to their small size and non-dispersive nature. Metrological applications will require a source of reproducible bright matter-wave solitons, making it of crucial importance to understand soliton formation and dynamics - in particular their phase-coherence and long-term stability. The ultimate goal of our research is a comprehensive understanding of the dynamical processes leading to bright matter-wave soliton formation, including both the initial collapse process and the long-term stability of the thus-formed solitons.

Research Strands:
The project is divided into three main research strands:
  • Exploration of the role of modulational instability in soliton formation, in both mean-field (Gross-Pitaevskii) and finite-temperature descriptions.
  • Exploration of possible modifications to the 1-D Lieb-Liniger theory, and use of this theory to study quantum bright solitons.
  • Development and numerical implementation of a second-order, quantum field-theoretical description of finite-temperature BEC dynamics.
  • By combining our work on these three strands, we hope ultimately to gain a more comprehensive understanding of the processes governing bright matter-wave soliton formation and dynamics than currently exists.

    Experimental Links:
    The Durham 85Rb experiment, led by S.L Cornish, will study bright solitons in BECs experimentally. As well as studying the role of relative phase in soliton-soliton collisions in more detail than previous experiments have achieved, the experiment will study the quantum reflection of solitons from laser potentials and surfaces, and later pioneer the use of bright solitons as a probe of atom-surface interactions.
    Poster Gallery:
    17-21 September 2009
    Content © Simon A Gardiner and Thomas P Billam, Durham University 2009