okay typos above aside i just read their paper. it's good work.
they solved a few well known, relatively simple quantum mechanics problems, in college (from the griffiths intro to quantum mechanics book) these problems are usually solved by talking about an electron in an electric potential.
these fine scientists solved a simple quantum mechanics problem not using an electric potential, but using a gravitational potential. the solution ends up resulting in two dimensionless constants that define the particulars of the solution that are measurable. in solving the equation of a they kept separate the inertial mass and the gravitational mass, and the two measurable constants are expressed in such a way in the setup that they are considering such that by measuring these two constants the inertial mass and gravitational mass may both be solved for (two equations, two unknowns).
they are proposing that this is a way of investigating experimentally the distinction if any between these two quantities.
also the appendix was really complicated and it was very hard to follow