Method for Measuring Silicon Quantum Dots with TMR Sensor

Although semiconductor performance has improved through miniaturization according to Moore’s Law, it is predicted that the physical limit will soon be reached. Thus, computational speed cannot be expected to improve with classical computers alone. Quantum computers present a solution to this problem. In this paper, we discuss the application of spintronics to the measurement of electron spins, which serve as qubits in quantum dot-based quantum computers. Specifically, we consider measuring quantum bits using a TMR (Tunnel Magnetoresistance) sensor, wherein the resistance changes depending on the magnetic direction. The purpose of this study is to determine whether this measurement method can improve the measurement speed compared with the conventional method of replacing the electron spin direction with charge information. Our findings suggest that if the current density, based on the shuttling frequency, is more than three times larger than the conventional current density, the proposed method can effectively measure qubits using the magnetization direction of the free layer.