I've seen a couple of lectures by Penrose where he describes an experiment to test superposition of physical location of a very small, but macroscopic object. I can't find a reference to it online, but the experiment involved sending a photon through a half-mirror, and depending on the route taken, to bounce it off a very light reflective object, so that the light pressure would transfer momentum to it and move it. Whether or not the photon does this, it is rerouted to make the same 'choice' and same momentum-transferring bounce many hundreds(millions?) of times, such that the movement of the object would actually be detectable, but for a certain while the actual physical location would be in a superposition. If I remember correctly Penrose was saying there is a theory whereby the time taken for decoherence would be inversely proportional to the size (complexity?) of the object, and if this were to be able to be measured thus proven it would explain why we don't see quantum phenomena in our macro world. Sorry for the terribly vague language but these were layman-directed lectures and I'm writing from memory, If someone has links to this experiment or other relevant studies I would very much like to read about these in more detail.