CaV₄O₉ (Calcium-Vanadium-Oxide) is a quantum spin liquid in which groups of four Vanadium spins are bound into plaquette resonant valence bond states. What happens when some of these spins are replaced by static vacancies or mobile holes? Using numerical techniques such as Monte Carlo simulations and Exact Diagonalizations, Stefan Wessel and Prof. Haas are exploring the various phases which may emerge.