  We experimentally demonstrate a robust dynamical decoupling protocol with
bounded controls using long soft pulses, eliminating a challenging requirement
of strong control pulses in conventional implementations. This protocol is
accomplished by designing the decoupling propagators to go through a Eulerian
cycle of the coupler group [Phys. Rev. Lett. 90, 037901(2003)]. We demonstrate
that this Eulerian decoupling scheme increases the coherence time by two orders
of magnitude in our experiment under either dephasing or a universal noise
environment.
