Metastable state and macroscopic quantum tunneling of binary mixtures

Rui‐Bin Liu, Shizhong Zhang

Roberto Cristiano, Luigi Frunzio, Yurii N. Ovchinnikov +1 more

Brian M. Siller, Brad R. Trees

B. Chatterjee, Ioannis Brouzos, Lushuai Cao +1 more

Kenichi Kasamatsu, Yukinori Yasui, Makoto Tsubota

We show theoretically the existence of a metastable state and the possibility of decay to the ground state through macroscopic quantum tunneling in two-component Bose-Einstein condensates with repulsive interactions. Numerical analysis of the coupled Gross-Pitaevskii equations clarifies the metastable states whose configuration preserves or breaks the symmetry of the trapping potential, depending on the interspecies interaction and the particle number. We calculate the tunneling decay rate of the metastable state by using the collective coordinate method under the WKB approximation. Then the height of the energy barrier is estimated by the saddle point solution. It is found that macroscopic quantum tunneling is observable in a wide range of particle numbers. Macroscopic quantum coherence between two distinct states is discussed; this might give an additional coherent property of two-component Bose condensed systems. Thermal effects on the decay rate are estimated.

Dmitry Solenov, Dmitry Mozyrsky

We study macroscopic properties of a system of weakly interacting neutral bosons confined in a ring-shaped potential with a Josephson junction. We derive an effective low energy action for this system and evaluate its properties. In particular, we find that the system possesses a set of metastable current-carrying states and evaluate the rates of transitions between these states due to macroscopic quantum tunneling and thermal activation mechanism. Finally, we discuss signatures of different metastable states in the time-of-flight images and argue that the effect is observable within currently available experimental technique.