We report on work in progress in quantum field theory about possible interactionsbetween coherent matter, i.e. matter described by a macroscopic wave function or a classical field, and a certain class of vacuum fluctuations, called Âzero-modes of the Einstein actionÂ. These are little-known virtual masses present in the vacuum state of quantum gravity. A couple of equal masses of this kind can be excited by an oscillating coherent source with frequency f and decays to its ground state emitting a virtual graviton, which can propagate and transfer momentum p to ordinary matter. The virtual masses recoil in the emission, and this amounts to a transfer of momentum Âp to the vacuum; this momentum can be passed in turn to some matter, or not. The energy hf for the process does not come from the vacuum, but from the coherent source. The ratio hf/p is of the order of 1 m/s. This model was developed to explain experimental results showing the emission of anomalous high-momentum radiation from certain superconductors, sometimes with a strong recoil of the emitters. The recoil is energetically quite efficient, at least at small power, and could be exploited for propulsion. It has not been tested in space, however, and our model cannot yet predict if the recoil is affected by the presence of near matter. (Another model predicts that it is not.) We also briefly mention a possible application of the anomalous radiation itself and we evaluate the (large) electric and magnetic field strength needed to produce an effect equivalent to that of a superconducting emitter.