  We consider a three-terminal system consisting of a quantum dot strongly
coupled to two superconducting reservoirs in the infinite gap limit and weakly
coupled to a normal metal. Using a real-time diagrammatic approach, we
calculate the dynamics of the proximity-induced pair amplitude on the quantum
dot. We find that after a quench the pair amplitude shows pronounced
oscillations with a frequency determined by the coupling to the
superconductors. In addition, it decays exponentially on a time scale set by
the coupling to the normal metal. Strong oscillations of the pair amplitude
occur also when the system is periodically driven both in the adiabatic and
fast-driving limit. We relate the dynamics of the pair amplitude to the
Josephson and Andreev current through the dot to demonstrate that it is an
experimentally accessible quantity.
