  Manipulation of quantum systems is the basis for many promising quantum
technologies. However, how quantum mechanical principles can be used to
manipulate the dynamics of quantum dissipative systems remains unanswered
because of strong decoherence effects arising from interaction with the
surrounding environment. In this work, we demonstrate that electron transfer
dynamics in molecular loop structures can be manipulated with the use of
Floquet engineering by applying a laser field. Despite strong dephasing, the
system's dynamics spontaneously breaks the chiral symmetry of the loop in a
controllable fashion, followed by the generation of a robust steady-state
electronic current without an external voltage. An exponential scaling law that
relates the magnitude of the current to the system-environment coupling
strength is revealed numerically. The breaking of chiral symmetry and the
consequent controllable unidirectional flow of electrons could be employed to
construct functional molecular electronic circuits.
