  The equivalence principle, being one of the building blocks of general
relativity, seems to be also crucial for analysis of quantum effects in
gravity. In this paper we consider the question if the equivalence principle
has to hold for consistency of performing quantum computation in gravitational
field. We propose an analysis with a looped evolution consisting of steps both
in the gravitational field and in the accelerated reference frame. We show that
without the equivalence principle the looped quantum evolution cannot be
unitary and looses its consistency. For this reasoning the equivalence
principle is formulated in terms of the gauge transformations and is analyzed
for particles acquiring an appropriate phases associated with the actions over
the looped path. In consequence, to keep consistency of quantum operations in
gravitational field, it is required to keep some quantum variant of the
equivalence principle. This proves importance of the quantized versions of this
fundamental gravitational principle for quantum information processing.
