Correlated dynamics of three-particle bound states induced by emergent impurities in Bose−Hubbard model

Bound states, known as particles tied together and moving as a whole, are profound correlated effects induced by particle−particle interactions. While dimer−monomer bound states are manifested as a single particle attached to a dimer bound pair, it is still unclear about quantum walks and Bloch oscillations of dimer−monomer bound states. Here, we revisit three-particle bound states in the Bose−Hubbard model and find that interaction-induced impurities adjacent to bound pair and boundaries cause two kinds of bound states: one is dimer−monomer bound state and the other is bound edge state. In quantum walks, the spread velocity of dimer−monomer bound state is determined by the maximal group velocity of their energy band, which is much smaller than that in the single-particle case. In Bloch oscillations, the period of dimer−monomer bound states is one third of that in the single-particle case. Emergence of bound edge states also requires that interaction-induced defects are greater than the effective tunneling strength of three-particle bound state. Our work provides new insights to basic mechanics and collective dynamics of three-particle bound states.