Defect engineering spin centers in interacting many-body Su-Schrieffer-Heeger chains

The ability to engineer topologically distinct materials opens the possibility of enabling novel phenomena in low-dimensional nanosystems, as well as manufacturing novel quantum devices. One of the simplest examples, the SSH model with both even and odd number of sites, demonstrates the connection between localized edge states and the topology of the system. We show that the SSH model hosts localized spin centers due to the interplay between the localized edge states and the on-site Hubbard interaction. We further show how one can engineer any number of localized spin centers within the chain by careful addition of defects. These spin centers are paired in spin-singlet or spin-triplet channels within each block separated by the defects, and together they construct an array of spin singlet and/or triplet qubits. The effect of on-site disorder on spin centers is also addressed. As this system is realizable experimentally, our findings describe a way for manipulating and engineering spin qubits and therefore provide a platform for performing many-body quantum simulations on spin excitations like magnons and triplons.