Analytical model of non-Markovian decoherence in donor-based charge quantum bits

We show that the quantum decoherence of a donor-based charge quantum bit (qubit) reveals non-Markovian features and comes to a halt at large times. The decoherence rate varies with time and even attains negative values, generating a non-exponential decay of the electronic coherence and a later recoherence. The resulting coherence time is inversely proportional to the temperature, thus leading to low decoherence below a material-dependent characteristic temperature.