Bound on the relaxation rates of solutions a quantum master equation

In a series of papers, culminating with a publication in the prestigious Reports on Progress on Physics together with Dariusz Chruściński, Frederik vom Ende and Gen Kimura we proved that the relaxation rates of a map solution of a quantum master equation obeys a non-trivial upper bound. The bound relates measurable quantities and only depends on the positivity class of the semi-group whereof the map is an element.
One reason that makes the bound particularly interesting because has no classical counterpart. as such it is a distinctive trait of open quantum system dynamics. The bound was conjectured by Kimura in the early 00's of this century and remained unproven for about two decades.