# Non-spreading matter-wave packets in a ring

## TL;DR

This paper analytically demonstrates the existence of unique non-spreading matter-wave packets in a free ring, explores their realization in Bose-Einstein condensates, and examines their stability under residual interaction noise.

## Contribution

The authors analytically identify a unique set of non-spreading matter-wave packets in a free ring and analyze their stability in Bose-Einstein condensates with residual interaction noise.

## Key findings

- Existence of a unique set of non-spreading matter-wave packets in a free ring.
- These wave packets can be realized in toroidal Bose-Einstein condensates using Feshbach resonance.
- Shape-keeping ability of the wave packets is linearly related to interaction noise strength.

## Abstract

Non-spreading wave packets and matter-wave packets in ring traps both have attracted great research interests due to their miraculous physical properties and tempting applications for quite a long time. Here, we proved that there exists only one set of non-spreading matter-wave packets in a free ring, and this set of wave packets have 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. Shape-keeping abilities of these wave packets are further studied quantitatively. We found that this set of wave packets have the same shape-keeping ability against interaction noise. And, the shape-keeping ability is linearly related to the interaction noise strength.