A Period-Finding Method for Shor´s Algorithm

Shor´s algorithm is a significant quantum algorithm for factoring a number N. The key technique of the Shor´s algo- rithm is turning the factoring problem into the problem of finding the period of a function. Based on the key technique and the monotony of the mode function, an approach how to determine the period of a function is introduced. Mean- while an important parameter selection for period-finding is optimized. Several experiments discussed imply that the approach and the parameter selection are both rigorous.