我们与 bequsi 相互作用在一个由两部组成的 3 水平系统调查 2-qutrit 逻辑门的实现。根据矩阵的 Cartan 分解, 2-qutrit 的单一的矩阵是进一系列可实现的矩阵的产品的 factorized。它等价于在系统,和控制目标上施加某个控制域被控制脉搏的一个序列通常获得。逻辑门被成为第一的 2-qutrit 的实现的一般讨论,然后实现第三交换门,第三的门明确地被讨论,并且控制脉搏的序列和实现这些门的飘移过程被给。
Optimal implementation of quantum gates is crucial for realization of quantum computation. We slightly modify the Khaneja-Glaser decomposition (KGD) for n-qubits and give a new Cartan subalgbra in the second step of the decomposition. Based on this modified KGD, we investigate the realization of three-qubit logic gate and obtain the result that a general three-qubit quantum logic gate can be implemented using at most 73 one-qubit gates rotations with respect to the y and z axes and 26 CNOT gates.
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。
Recently, Vatan and Williams utilize a matrix decomposition of
SU(2n) introduced by Khaneja and Glaser to produce {\tt CNOT}-efficient circuits for arbitrary three-qubit unitary evolutions. In this note, we place the Khaneja Glaser Decomposition ({\tt KGD}) in context as a
SU(2n)=KAK decomposition by proving that its Cartan involution is type {\bf AIII}, given
n≥3. The standard type {\bf AIII} involution produces the Cosine-Sine Decomposition (CSD), a well-known decomposition in numerical linear algebra which may be computed using mature, stable algorithms. In the course of our proof that the new decomposition is type {\bf AIII}, we further establish the following. Khaneja and Glaser allow for a particular degree of freedom, namely the choice of a commutative algebra
a, in their construction. Let
χ1n be a {\tt SWAP} gate applied on qubits
1,
n. Then
χ1nvχ1n=k1ak2 is a KGD for $\mathfrak{a}=\mbox{span}_{\mathbb{R}} \{ \chi_1^n ( \ket{j}\bra{N-j-1} -\ket{N-j-1}\bra{j}) \chi_1^n \}$ if and only if
v=(χ1nk1χ1n)(χ1naχ1n)(χ1nk2χ1n) is a CSD.