  We analyze the transient response of quantum dot thermal machines that can be
driven by hyperfine interaction acting as a source of classical information.
Our setup comprises a quantum dot coupled to two contacts that drive heat flow
while coupled to a nuclear spin bath. The quantum dot thermal machines operate
both as batteries and as engines, depending on the parameter range. The
electrons in the quantum dot interact with the nuclear spins via hyperfine
spin-flip processes as typically seen in solid state systems such as GaAs
quantum dots. The hyperfine interaction in such systems, which is often treated
as a deterrent for quantum information processing, can favorably be regarded as
a driving agent for classical information flow into a heat engine setup. We
relate this information flow to Landauer's erasure of the nuclear spin bath,
leading to a battery operation. We further demonstrate that the setup can
perform as a transient power source even under a voltage bias across the dot.
Focusing on the transient thermoelectric operation, our analysis clearly
indicates the role of Landauer's erasure to deliver a higher output power than
a conventional quantum dot thermoelectric setup and an efficiency greater than
that of an identical Carnot cycle in steady state, which is consistent with
recently proposed bounds on efficiency for systems subject to a feedback
controller. The role of nuclear spin relaxation processes on these aspects is
also studied. Finally, we introduce the Coulomb interaction in the dot and
analyze the transient thermoelectric response of the system. Our results
elaborate on the effective use of somewhat undesirable scattering processes as
a non-equilibrium source of Shannon information flow in thermal machines and
the possibilities that may arise from the use of a quantum information source.
