Separation and approximate separation of multipartite quantum gates
The number of qubits of current quantum computers is one of the most
dominating restrictions for applications. So it is naturally conceived to use
two or more small capacity quantum computers to form a larger capacity quantum
computing system by quantum parallel programming. To design the parallel
program for quantum computers, the primary obstacle is to decompose quantum
gates in the whole circuit to the tensor product of local gates. In the paper,
we first devote to analyzing theoretically separability conditions of
multipartite quantum gates on finite or infinite dimensional systems.
Furthermore, we perform the separation experiments for $n$-qubit quantum gates
on the IBM's quantum computers by the software Q$|SI\rangle$. Not surprisedly,
it is showed that there exist few separable ones among multipartite quantum
gates. Therefore, we pay our attention to the approximate separation problems
of multipartite gates, i.e., how a multipartite gate can be closed to separable
ones.
Kan He Shusen Liu Jinchuan Hou