  Time in relativity theory has a status different from that adopted by
standard quantum mechanics, where time is considered as a parameter measured
with reference to an external absolute Newtonian frame. This status strongly
restricts its role in the dynamics of systems and hinders any formulation to
merge quantum mechanics with general relativity, specifically when considering
quantum gravity. To overcome those limitations, several authors tried to
construct an operator which is conjugate to the Hamiltonian of quantum systems
implementing some essential features of the relativistic time. These
formulations use the concept of internal or intrinsic time instead of the
universal coordinate time used in textbooks. Furthermore, recently it is
remarked that the consideration of time with relativistic features could
enhance the analysis techniques in quantum information processing and have an
impact on its status in causal orders and causal structures of quantum
information. The role of clocks, their accuracy and stability has become an
important issue in quantum information processing. This article present a
substantiative review of recent works which reflect the possibility of
utilizing quantum time, measured by quantum clock devised according to
Page-Wootters scheme, to stand as a resource for quantum information
processing.
