Non-spreading matter-wave packets in a ring

Abstract

Non-spreading wave packets and matter-wave packets in ring traps have both attracted great research interest for quite a long time due to their remarkable physical properties and intriguing applications. Here, we prove that there is only one set of non-spreading matter-wave packets in a free ring, and this set of wave packets has been found analytically. These non-spreading matter-wave packets can be realized in a toroidal trapped Bose–Einstein condensate system with the help of Feshbach resonance to eliminate contact interaction between atoms. Since experimentally residual interaction noise will always exist, its effect on the stability of these non-spreading wave packets is also examined. Qualitatively, under weak residual interaction noise, these non-spreading wave packets can preserve their shape for quite a long time, while a stronger interaction noise will induce shape breathing of the wave packets. The shape-keeping abilities of these wave packets are further studied quantitatively. We found that this set of wave packets has the same shape-keeping ability against interaction noise, and the shape-keeping ability is linearly related to the strength of the interaction noise.