Equilibrium and Non-equilibrium Condensation Phenomena in a Tuneable Homogeneous Bose Gas
Abstract
During this period (the first year of the grant) we have worked on 5 projects, 2 on equilibrium and 3 on non-equilibrium phenomena (which are the two main goals of the grant). 1. On our new apparatus with 39K BEC in a box trap (the achievement of which was the first major goal of the grant) we have studies the stability and collapse dynamics of a BEC with attractive interactions. The most important outcome of this project was the first observation of the so-called weak collapse of a matter-wave field, which was theoretically predicted 30 years ago. 2. On the same apparatus we have also studied the correlations and coherence properties of a BEC with strong repulsive interactions, using Bragg spectroscopy. The two main outcomes of this work are the observations of the "back-banding" of the Bragg spectrum and deviations from the Bogoliubov theory, which is conceptually linked to the roton physics in a strongly interacting system, and of the reversible quantum depletion of the condensate, driven by adiabatic tuning of the interaction strength. 3. On the previously existing 87Rb-in-a-box setup we have completed the study of the emergence of a turbulent cascade in a continuously driven degenerate Bose gas. This experiment established the homogeneous Bose gas as a unique new research platform for studies of turbulence (including the interplay of quantum and classical effects), which allows for the first time direct cross-validation of experiments and first-principle numerical simulations of realistic experimental conditions. 4. On the same apparatus we have also started the study of the phase-relaxation dynamics in a phase-disordered (turbulent or quench-cooled) deeply degenerate Bose gas. 5. Finally, with a 39K gas we have also intereferometrically studied both two- and three-body correlations (so-called two- and three-body contacts) in a strongly-interacting (unitary) Bose gas on the border of condensation. The major breakthrough of this work is the measurement of the so-called three-body contact, which represents the first observation of the effect of three-body Efimov physics on the coherent behaviour of a many-body system.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2018
- Source ID
- W911NF1510444
Entities
People
- Zoran Hadzibabic
Organizations
- Army Contracting Command
- United States Army
- University of Cambridge