  We observe the dissipative dynamics of a dense, strongly interacting gas of
bosonic atom pairs in an optical lattice, controlling the strength of the
two-body interactions over a wide parameter regime. We study how three-body
losses contribute to the lattice dynamics, addressing a number of open
questions related to the effects of strong dissipation in a many-body system,
including the relationship to the continuous quantum Zeno effect. We observe
rapid break-up of bound pairs for weak interactions, and for stronger
interactions we see doublon decay rates that are asymmetric when changing from
attractive and repulsive interactions, and which strongly depend on the
interactions and on-site loss rates. By comparing our experimental data with a
theoretical analysis of few-body dynamics, we show that these features
originate from a non-trivial combination of dissipative dynamics described by a
lattice model beyond a standard Bose-Hubbard Hamiltonian, and the modification
of three-atom dynamics on a single site, which is generated alongside strong
three-body loss. Our results open new possibilities for investigating bosonic
atoms with strong three-body loss features, and allow for the better
understanding of the parameter regimes that are required to realize strong
effective three-body interactions.
