QUANTUM MEMROY DEVICE

A quantum memory device in which a memory operation is enabled even if the structure of a Josephson device is reduced in size. Each memory cell of the quantum memory device includes a superconducting quantum interference device having two Josephson junctions, a write word line for supplying a current to the superconducting quantum interference device, a write data line and a magnetic field detection line magnetically coupled with the superconducting quantum interference device, a three-terminal switching device for turning a signal of the magnetic field detection line on and off to transfer the signal to a read data line, and a read word line connected to a gate of the three-terminal switching device. The junction area of the Josephson junction is made small to oscillate a magnetic flux so that information is stored in accordance with the phase of oscillation of the magnetic flux. An induced current produced by an oscillating flux of a dummy cell and an induced current produced by an oscillating flux of each memory cell are compared to detect the phases of flux oscillation of the dummy and memory cells, thereby reading information.