We develop a non-Markovian extension to the caldeira-leggett master equation for
quantum Brownian motion by using the timescale of the bath as a small parameter around
which to perform a perturbative expansion. This framework allows us to deal directly
with the time non-locality of the non-Markovian regime. We derive an exact description
of the evolution of the reduced density matrix and obtain a new quantum master equa-
tion with non-Markovian corrections added perturbatively to the standard Lindblad form.
The resulting simulations show new dynamics and a strong deviation from Markovian
behaviour. We observe that quantum coherences survive far longer than in the Marko-
vian limit. In particular, when the system is fully non-Markovian, quantum phenomena
experience a form of decoherence that behaves functionally like an inverse-power law.
These results may have important implications in quantum technologies and biology as
they suggest environments can be engineered to support long-lived quantum coherence.