  Our recent paper (arXiv:1701.04298 [quant-ph]) discussed the occurrence of a
coupling of centre of mass and internal degrees of freedom for complex quantum
systems in non-inertial frames. There, we pointed out that an external force
supporting the system against gravity plays a crucial role for the coupling
between center of mass position to the internal degrees of freedom. In a
comment (arXiv:1702.06670 [quant-ph]) to our paper, Pikovski et al. question
our conclusion and present the argument that the lack of the coupling term
would be in contradiction with the observation of gravitational time dilation
using atomic clocks. Here, we elaborate on our results in reply to their
criticism and clarify why our arguments remain valid.
