# 量子计算机

## 基本概念

• 傳統计算机具有如下特点：
1. 其输入态和输出态都是傳統信号，用量子力学的语言来描述，也即是:其输入态和输出态都是某一力学量的本征态。如输入二进制序列$0110110$，用量子记号，即$\left| 0110110 \right\rangle$。所有的输入态均相互正交。对经典计算机不可能输入如下叠加态$c_1 \left|0110110 \right\rangle + c_2 \left| 1001001 \right\rangle$
2. 傳統计算机内部的每一步变换都演化为正交态，而一般的量子变换没有这个性质，因此，傳統计算机中的变换（或计算）只对应一类特殊集。

• 因此量子计算机的特点为:
1. 量子计算机的输入态和输出态为一般的叠加态，其相互之间通常不正交；
2. 量子计算机中的变换为所有可能的正变换。得出输出态之后，量子计算机对输出态进行一定的测量，给出计算结果。

## 參考

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