Two-body and three-body contacts for identical Bosons near unitarity.
In a recent experiment with ultracold trapped Rb85 atoms, Makotyn et al. studied a quantum-degenerate Bose gas in the unitary limit where its scattering length is infinitely large. We show that the observed momentum distributions are compatible with a universal relation that expresses the high-momentum tail in terms of the two-body contact C2 and the three-body contact C3. We determine the contact densities for the unitary Bose gas with number density n to be C2 ≈ 20 n(4/3) and C3 ≈ 2n(5/3). We also show that the observed atom loss rate is compatible with that from 3-atom inelastic collisions, which gives a contribution proportional to C3, but the loss rate is not compatible with that from 2-atom inelastic collisions, which gives a contribution proportional to C2. We point out that the contacts C2 and C3 could be measured independently by using the virial theorem near and at unitarity, respectively.
Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
D Hudson
DH
Smith
Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
Eric
E
Braaten
Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Daekyoung
D
Kang
Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA and Department of Fundamental Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
Lucas
L
Platter