In ultracold atomic gases, Feshbach resonances give us access to the unitary regime, where the s-wave scattering length diverges and two-body interactions are as strong as allowed by the laws of quantum mechanics. Following more than a decade of exciting experiments on the unitary Fermi gases, the unitary Bose gases have more recently emerged as a new experimental frontier. An additional challenge in understanding these gases is that due to rapid three-body recombination they are intrinsically non-equilibrium systems, which are in practice studied using rapid interaction quenches. I will give an overview of recent experiments trying to understand the dynamics and thermodynamics following a quench of a Bose gas to unitarity. These include observations of the universal decay dynamics [1], measurements of the energy and condensed fraction of degenerate unitary Bose gases [2], and observations of non-universal three-body Efimov physics in these systems [3].
[1] Universal Scaling Laws in the Dynamics of a Homogeneous Unitary Bose Gas,
C. Eigen, J. A. P. Glidden, R. Lopes, N. Navon, Z. Hadzibabic, and R. P. Smith,
Phys. Rev. Lett. 119, 250404 (2017).
[2] Universal prethermal dynamics of Bose gases quenched to unitarity,
C. Eigen, J. A. P. Glidden, R. Lopes, E. A. Cornell, R. P. Smith, and Z. Hadzibabic,
Nature 563, 221 (2018).
[3] Two and three-body contacts in the unitary Bose gas,
R. J. Fletcher, R. Lopes, J. Man, N. Navon, R. P. Smith, M. W. Zwierlein, and Z. Hadzibabic,
Science 355, 377 (2017).