If you look at the actual article, the claim is not that
"they show how it is possible to create situations in the quantum world in which the effects of inertial and gravitational mass must be different."
The paper claims that, in a uniform gravitational field, using quantum mechanical experiments it is possible to measure more than just the ratio of inertial to gravitational mass, NOT that quantum mechanics requires them to be different. Apparently, classically, only the ratio can be measured in a uniform gravitational field.
Slashdot Mirror
If you look at the actual article, the claim is not that "they show how it is possible to create situations in the quantum world in which the effects of inertial and gravitational mass must be different."
The paper claims that, in a uniform gravitational field, using quantum mechanical experiments it is possible to measure more than just the ratio of inertial to gravitational mass, NOT that quantum mechanics requires them to be different. Apparently, classically, only the ratio can be measured in a uniform gravitational field.