Preparation of the spin-Mott state: a spinful Mott insulator of repulsively bound pairs

We observe and study a special ground state of bosons with two spin states in an optical lattice:the spin-Mott insulator, a state that consists of repulsively bound pairs which is insulating for bothspin and charge transport. Because of the pairing gap created by the interaction anisotropy, it canbe prepared with low entropy and can serve as a starting point for adiabatic state preparation.We find that the stability of the spin-Mott state depends on the pairing energy, and observe twoqualitatively different decay regimes, one of which exhibits protection by the gap.