I will present a partial reformulation of quantum mechanics which is based on the Batalin-Vilkovisky (BV) formalism. The BV-algebraic framework will be applied to the harmonic oscillator. Using a homotopy transfer to the phase space, I will show how to compute normalised quantum expectation values. This talk will be based on joint work with C. Chiaffrino and O. Hohm, arXiv: 2112.11495.