Quantum Dynamics of a Charge Qubit in a Squeezed Field

The quantum dynamics of a charge qubit, which makes up of a single-Cooper-pair box, are explored. The Cooper-pair box is irradiated by a squeezed field in an ideal one-mode cavity. By the result of the Schrodinger equation, the Cooper pairs number 〈N〉 is conveniently obtained. Then it is proved that the oscillations of the Cooper-pair number 〈N〉 are decreasing with the increasing squeezing parameter of the squeezed field.