量子计算来源于量子相干和量子纠缠的特性，但是这两个性质都很脆弱和易于出错，很容易被称为消相干的过程破坏掉，因此如何克服消相干的影响已成为实现量子计算机的一个关键．利用非跃迁轨迹和Berry以及AA几何相位公式，计算了在绝热和非绝热情况下，分别由单模和双模消相干量子场所产生的自旋为1／2系统的几何相位。利用量子跃迁方法，当考虑绝热和非绝热演化时，发现对于非跃迁轨道，其相位修正值是不同的。最后我们从基本原理和量子计算的观点讨论了其结果的意义。

Quantum computer takes advantages from properties of superposition and entanglement,which are also very fragile and easy to be error. But they may be destroyed easily by a process called decoherence. Therefore,how to overcome the effect of decoherence is key to implement quantum computer. Using the no-jump trajectory,Berry's and AA's formula for geometric phase,we calculate the geometric phase of a spin-1/2 system driven by one and two mode quantum fields subject to decoherence in the adiabatic and nonadiabatic case,respectively. By quantum jump method,we find that the corrections to its phase for the no-jump trajectory are different when considering adiabatic and nonadiabatic evolutions. Finally,we discuss the implications of our results from fundamental and quantum computational points.