They showed that transporting the quantum coherent exciton can be either retarded or assisted by environmental noise, depending on just how loud that noise is. If the system is too cold and quiet, then the exciton tends to oscillate aimlessly without actually getting anywhere in particular; whereas in a very hot and noisy environment something called the quantum Zeno effect kicks in, which retards quantum transport. Between these two extremes is a Goldilocks zone where vibrations are just right for quantum transport.
