The present invention relates to the architecture of a quantum RAM, a method for using classical data in quantum computing by inputting the classical data as quantum data, and a system and method of operating a quantum database using the architecture. Quantum computing can achieve an exponential speed-up in some applications using a large parallel process provided by a quantum database in which information can be superposed. The present invention proposes an efficient quantum database architecture and protocol that can record and search for classical information with a quantum circuit.