We describe a new and experimentally feasible protocol for performing
fundamental tests of quantum mechanics with massive objects. In our approach a
single two level system is used to probe the motion of a nanomechanical
resonator via multiple Ramsey interference measurements. This scheme enables
the measurement of modular variables of macroscopic continuous variable systems
and we show that correlations thereof violate a Leggett-Garg inequality and can
be applied for tests of quantum contextuality. Our method can be implemented
with a variety of different solid state or photonic qubit-resonator systems and
provides a clear experimental signature to distinguish the predictions of
quantum mechanics from those of other alternative theories at a macroscopic
scale.Comment: 5 pages plus Supplementary Material. Published in Phys. Rev. Let
