Fluctuations in imploding Bose-Einstein condensates

Quantum and thermal effects play important roles in the fluctuations of ultracold Bose gasses, yet the fluctuations remain difficult to probe experimentally in 3D bulk systems. We report on a joint experimental-theoretical effort which seeks to amplify these fluctuations via a quench from positive to negative scattering length. Following such a quench, initial fluctuations in the gas, whether seeded by a lattice potential, thermal fluctuations, or quantum fluctuations, are amplified on a time-scale which is fast compared to the collapse of the cloud. These can be compared to a variety of theoretical models, which predict the static structure factor as a function of time and momentum in the collapsing gas.