The "processing and storage of information" functions of the computer have greatly accelerated the pace of "human progress." To solve any mathematical or computational problem using a computer, an "efficient algorithm" for solving the problem is required. A quantum computer is a device that can perform computational tasks based on the principles of quantum mechanics. In an actual quantum computer, parallel processing can indeed be performed using a minimum of resources which is impossible in a classical computer. To perform parallel processing in a classical computer, huge resources and space are required. A qubit is a smallest unit of information in a quantum computer similar to a bit in a classical computer. Classical computers consist of wires and logic gates. A quantum algorithm can only be run on a quantum computer. A quantum computer is built from a quantum circuit that consists of quantum gates and wires.