The quantum gate array is the natural quantum generalization of acyclic combinational logic " circuit " studied in conventional computational complexity theory . in 1995 , barenco showed that almost any two - bit gate is universal , so building a feasible two - bit logic gate is the first step to engineer a quantum computer . in principle , the quantum bit can be carried by any two states system 在众多的量子计算机模型中目前讨论最广泛的是量子计算机门组网络模型,量子计算机门组网络模型是经典计算机门组网络结构的量子推广,它是根基于barenco等人所证明的“一个两比特受控操作和对单比特进行任意操作的门可以构成一个‘通用量子逻辑门组’ ”之上的。
Computational complexity theory is a branch of the theory of computation in theoretical computer science and mathematics that focuses on classifying computational problems according to their inherent difficulty, and relating those classes to each other. A computational problem is understood to be a task that is in principle amenable to being solved by a computer, which is equivalent to stating that the problem may be solved by mechanical application of mathematical steps.