1D Bose Gases

Bosonic atoms confined in 1D approximate a Lieb-Liniger (L-L) gas. The L-L model describes particles that interact pairwise with delta-function potentials. The model is integrable, which means that it is possible to exactly solve for the many-body wavefunction and  there are many extra conserved quantities (either an infinite number or one per particle, depending on how you count). In the past couple of decades, our group and others have experimentally demonstrated many of the features of this model. Perhaps the most interesting is that the near-integrability of 1D Bose gases implies that they do not thermalize, at least for a very long time.  Thus we can use this experimental system to better understand thermalization and the out-of-equilibrium dynamics of many-body quantum systems.

A sample of the observations we have made with this apparatus are:

     fermionization in the strong coupling (Tonks-Girardeau) limit;

     quantitative demonstrations of central features of the L-L model in equilibrium across coupling regimes;

     a quantum Newton’s cradle, which set a long time limit on the thermalization rate of these gases;

     self-trapped suppression of tunneling among 1D tubes;

     quantum distillation, in which 1D atoms in a lattice self-purify their defects;

     dynamical fermionization;

     the direct observation of rapidities (the momenta of the quasiparticles that describe the Lieb-Linger gas);

     and precision tests of the theory of generalized hydrodynamics (GHD).

We have most recently been working on better understanding what happens immediately after a quantum quench.  In the near future, we will extend our studies of rapidities and dynamics by controllably lifting integrability in several distinct ways.

Our overarching goal is to use the clarity of these experiments and their proximity to theoretically solvable problems to develop overarching theories that describe a wide range (perhaps all) of non-equilibrium quantum dynamics.