While the spin-orbit coupling in carbon nanotubes was originally thought to be small due to the light atomic mass of the carbon nucleus, it turns out that the p-like nature of the electron orbitals combined with the curvature of the nanotube surface can lead to a measurable spin-orbit gap in carbon nanotube quantum dots.

In their work published in Nature Communications, Steele et al found that the spin orbit coupling was even larger than expected, raising new questions about the nature of electronic states in few-electron carbon nanotube quantum dots.