List of publications viib This is by no means a complete discussion of topological systems. Only the necessary background is presented for understanding 1D topological chains, as they are the protagonist of this thesis. c For the explicit form of the Hamiltonian, see Chapters 2 and 3. 2 Exact ground states for interacting Kitaev chains This chapter is based on: J. Wouters, H. Katsura and D. Schuricht, Exact ground states for interacting Kitaev chains, Physical Review B 98(11), 155119 (2018). J.W. performed most of the calculations and all numerical simulations, discussed the results and contributed to the final version of the manuscript.We introduce a frustration-free, one-dimensional model of spinless fermions with hopping, p-wave superconducting pairing and alternating chemical potentials. The model possesses two exactly degenerate ground states even for finite system sizes. We present analytical results for the strong Majorana zero modes, the phase diagram and the topological order. Furthermore, we generalise our results to include interactions.