  In this paper we present a quantum algorithm that uses noise as a resource.
The goal of our quantum algorithm is the calculation of operator averages of an
open quantum system evolving in time. Selected low-noise system qubits and
noisy bath qubits represent the system and the bath of the open quantum system.
All incoherent qubit noise can be mapped to bath spectral functions. The form
of the spectral functions can be tuned digitally, allowing for the time
evolution of a wide range of open-system models at finite temperature. We study
the feasibility of this approach with a focus on the solution of the spin-boson
model and assume intrinsic qubit noise that is dominated by damping and
dephasing. We find that classes of open quantum systems exist where our
algorithm performs very well, even with gate errors as high as 1%. In general
the presented algorithm performs best if the system-bath interactions can be
decomposed into native gates.
