Irregular Spin Tunnelling for Spin-1 Bose-Einstein Condensates in a Sweeping Magnetic Field

TL;DR

This study explores how spin-1 Bose-Einstein condensates exhibit irregular and chaotic spin tunnelling behaviors under different magnetic field sweeping rates, revealing complex dynamics and potential experimental implications.

Contribution

It provides a detailed analysis of spin tunnelling dynamics in spin-1 BECs under varying magnetic field sweep rates, highlighting the emergence of chaotic regimes and regular patterns.

Findings

No tunnelling in adiabatic and sudden limits.

Chaotic-like tunnelling at moderate sweep rates.

Periodic tunnelling patterns at high resolution.

Abstract

We investigate the spin tunnelling of spin-1 Bose-Einstein condensates in a linearly sweeping magnetic field with a mean-field treatment. We focus on the two typical alkali Bose atoms $^{87}Rb$ and $^{23}Na$ condensates and study their tunnelling dynamics according to different sweeping rates of external magnetic fields. In the adiabatic (i.e., slowly sweeping) and sudden (i.e., fast sweeping) limits, no tunnelling is observed. For the case of moderate sweeping rates, the tunnelling dynamics is found to be very sensitive on the sweeping rates with showing a chaotic-like tunnelling regime. With magnifying the regime, however, we find interestedly that the plottings become resolvable under a resolution of $10^{-4}$ G/s where the tunnelling probability with respect to the sweeping rate shows a regular periodic-like pattern. Moreover, a conserved quantity standing for the magnetization in experiments is found can dramatically affect the above picture of the spin tunnelling. Theoretically we have given a reasonable interpretation to the above findings and hope our studies would bring more attention to spin tunnelling experimentally.