Abstract
We provide two novel approaches to calculate the decoherence time of the coupled quantum dots. These two approaches are much more succinct and intuitive than the previous works such as NIBA. Our approaches provide good physical insight for the mechanism of the decoherence time. One- and two-phonon transition rates are calculated with Fermi’s golden rule and results are in agreement with relevant works. The approximate multi-phonon transition rate is obtained and we find there is a temperature scale T0 which can determine when the multi-phonon transition dominates. Numerical calculations of the decoherence time of the coupled quantum dots are given and we find the quantum computation based on coupled quantum dots can be realized at low temperature, ie. not far above T0, but otherwise the decoherence time is too short for performing quantum computation.