They propose that electron tunneling between these quantum wells, which are between 3.7 and 6.5 Ångstroms apart, is the superconducting mechanism.

Uh oh. We’re goin tunneling boys and girls. This is how we end the universe as we know it.

Edit: Mandatory kurzgesagt link https://www.youtube.com/watch?v=4_aOIA-vyBo

Edit 2: Wrong link. https://www.youtube.com/watch?v=ijFm6DxNVyI