Note on Implementation of Three-Qubit SWAP Gate

在这份报纸， three-quhit 的合成和实现交换门被讨论。three-quhit 交换门能被分解成 2 two-qubit 的产品交换门，并且它能由 6 扇 CNOT 门被认识到。尽管结果很简单，研究说明了那，为 multi-qubit 门的矩阵分解的当前的方法不能得到那。然后 three-qubit 的实现与 Ising 在三个旋转系统交换门相互作用被调查，控制脉搏和飘移过程的顺序被给实现门。它需要 23 控制脉搏和 12 个飘移过程。因为相互作用不能随意断断续续地被交换， three-qubit 的实现也在特定的量系统交换门不能简单地下来到 2 two-qubit 交换门。

In this paper, the synthesis and implementation of three-qubit SWAP gate is discussed. The three-qubit SWAP gate can be decomposed into product of 2 two-qubit SWAP gates, and it can be realized by 6 CNOT gates. Research illustrated that although the result is very simple, the current methods of matrix decomposition for multi-qubit gate can not get that. Then the implementation of three-qubit SWAP gate in the three spin system with Ising interaction is investigated and the sequence of control pulse and drift process to implement the gate is given. It needs 23 control pulses and 12 drift processes. Since the interaction can not be switched on and off at will, the realization of three-qubit SWAP gate in specific quantum system also can not simply come down to 2 two-qubit SWAP gates.