ICQM Postdoctoral Fellow Ying Hu publishs a report in PRL
Visualization of dimensional effects in collective excitations of optically trapped quasi-two-dimensional Bose gases
One of the most fascinating aspects of many-body systems is the role of dimensionality. For example, in two dimensions (2D), remarkable phenomena arise including high-Tc superconductivity and Berezinskii-Kosterlitz-Thouless transition. The advent of highly controllable ultracold gases has offered unprecedentedly new opportunities to explore low-D behaviors and dimensional crossovers. Particularly, observing directly dimensional effect would present an important step in revealing the interplay between dimensionality and quantum fluctuations in low-D. In this aspect, Dr. Hu, a Postdoctoral Fellow in Prof. Biao Wu’s group from the International Center for Quantum Materials, Peking University, has recently proposed with their collaborators to `visualize’ dimensional effects via collective excitations of optically trapped quasi-two-dimensional Bose gases .
In quasi-two dimensions (quasi-2D), where excitations are frozen in one direction, the scattering amplitudes exhibit 2D features of the particle motion and a 3D to 2D dimensional crossover emerges in the behavior of scattering. They have explored its physical consequences and found broken Pitaevskii-Rosch symmetry by arbitrarily small 2D effects. They have shown that such broken dynamical symmetry induces a frequency shift in breathing mode from the order of 0.5% to more than 5% in transiting from the 3D-scattering to the 2D-scattering regime. Comparisons with other relevant effects suggest their results observable within current experimental capabilities. Their work has published on Phys. Rev. Lett. 107, 110401 (2011), and supported by NSF of China.