There has been some interest in looking at quantum interference experiments using neutrons falling due in the Earth's gravity (see for example Abele and Leeb, New Journal of Physics 14 (2012)). In quantum bouncing ball experiments, the gravity potential leads to discrete energy levels in the range $\approx peV$. It made me wonder: Presumably such calculations are only valid in weak gravitational fields but it made me what are the limits on the size of the gravitational field that can be used to do such calculations? For example, if you considered a neutron star of (say) two solar masses and looked at the energy do an orbiting neutron of order 10 km, then the energy of a "Bohr type" model eigenstate would be enormous.

  • $\begingroup$ The problem is you need the systems to maintain coherence for the interference to occur, and it gets increasingly difficult to do this as the objects get bigger. As far as I know the largest objects for which interference has been observed are polymers with mass of about 10,000 Daltons (which is a bit over $10^{-20}$ grams!). $\endgroup$ – John Rennie Apr 4 '16 at 18:49
  • $\begingroup$ Not particular thinking of interference, just the limits of using gravity in a Schrodinger like equation. $\endgroup$ – jim Apr 4 '16 at 19:45

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