Whenever I read about these kinds of discoveries I wonder about the circumstances under which the experiment was dreamed up. "Hey, I had this idea about temperatures... What if we got a shitton of lasers and magnetic fields and used them to constrain the movement of already extremely cold atoms while simultaneously increasing the amount of energy they have. That'd... that'd technically work, right?" "Dude, I don't know. Have another hit."
They mention in the paper that similar experiments have been done before, albeit without the temperature trick to keep the lattice from imploding:Then they tune the interactions to be attractive and at the same time turn their trap upside down to be an anti-trap. Finally, they melt the Mott insulator to obtain an attractive superfluid. These anti-traps have been used before, to create a self-propagating pulse of atoms that does not disperse (a bright solution) from attractive gases in one dimension (7, 8)