Short-time decoherence of Josephson charge qubits

In this paper we investigate the short-time decoherence of single Josephson charge qubit (JCQ). The measure of decoherence is chosen as the maximum norm of the deviation density operator. It is shown that when the temperature is low enough (for example, T∼30mK), within the elementary gate-operation time τg∼12.7ps, the decoherence is smaller than 10-4 for the present setup of JCQ. Thus, the JCQ is suitable for taking the blocks of quantum computer according to the DiVincenzo low-decoherence criterion.