  The interaction between a quantum charge and a dynamic source of a magnetic
field is considered in the Aharonov-Bohm scenario. It is shown that, in weak
interactions with a post-selection of the source, the effective vector
potential is, generally, complex-valued. This leads to new experimental
protocols to detect the Aharonov-Bohm phase before the source is fully
encircled. While this does not necessarily change the nonlocal status of the
Aharonov-Bohm effect, it brings new insights into it. Moreover, we discuss how
these results might have consequences for the correspondence principle, making
complex vector potentials relevant to the study of classical systems.
