  The ability to maintain coherence and control in a qubit is a major
requirement for quantum computation. We show theoretically that long coherence
times can be achieved above boiling point of liquid helium in charge qubits of
oxide double quantum dots. Detuning the dots to a fraction of the optical
phonon energy, increasing the electron-phonon coupling, reducing the
adiabaticity, or decreasing the temperature enhances the coherence time. We
consider a system that is initially decoupled from the phonon bath in the
polaronic frame of reference and solve the non-Markovian quantum master
equation; we find that the system decoheres after a long time, despite the fact
that no energy is exchanged with the bath.
