 Quantum mechanics is one of the focuses of the research group led by Olimpia Lombardi which developed its work in two directions: the interpretation of the theory and the analysis of the meaning of decoherence. Regarding the first topic, Lombardi and Mario Castagnino proposed the modal-Hamiltonian interpretation of quantum mechanics: a realist, non-collapse interpretation that endows the Hamiltonian with a determining role. The interpretation proved to be effective in explaining ideal and non-ideal measurements and many other well-known physical situations such as hydrogen atom, Zeeman effect, fine structure, etc. (Lombardi and Castagnino 2008). The interpretation was reformulated in a Galilean invariant form (Ardenghi, Castagnino, and Lombardi 2009; Lombardi, Castagnino, and Ardenghi 2010), and was applied to further situations, such as the non-collapse account of consecutive measurements in physics (Ardenghi, Lombardi, and Narvaja 2013), the understanding of quantum decoherence (Lombardi, Ardenghi, Fortin, and Castagnino 2011), the view of quantum measurement in informational terms (Lombardi, Fortin, and López 2015), and the problem of optical isomerism in chemistry (Fortin, Lombardi, and Martínez González 2016, 2018). In addition, the modal-Hamiltonian interpretation proposes a bundle-of-properties ontology that adequately accounts for contextuality and indistinguishability (da Costa, Lombardi, and Lastiri 2013; da Costa and Lombardi 2014), but without preventing the emergence of particles under certain particular circumstances (Lombardi and Dieks 2016).