Quantum states of ultracold neutrons in a gravitational field are characterized through gravitational resonance spectroscopy. This paper discusses systematic effects that appear in the spectroscopic measurements. The discussed frequency shifts—which we call the Stern-Gerlach shift, interference shift, and spectator-state shift—appear in conceivable measurement schemes and have general importance. These shifts have to be taken into account in precision experiments.

• Received 18 November 2014
• Publisher error corrected 9 March 2015

DOI:https://doi.org/10.1103/PhysRevD.91.042006