Introduction

Electron spins in semiconductor quantum dots are good candidates of quantum bits for quantum information processing.

Basic operations of the qubit have been realized in recent years: initialization, manipulation of single spins, two-qubit entanglement operations, and readout. Now it becomes crucial to demonstrate the scalability of this architecture by conducting spin operations on a scaled up system.

We demonstrate single-electron spin resonance in a quadruple quantum dot.

Experiment

The left picture shows a scanning electron micrograph of the device. A quadruple quantum dot is formed at the position of the four circles. We can detect the charge state by monitoring quantum dot sensors on the upper side.

We apply microwaves to induce the electron spin resonance. The microwave electric field and the magnetic field created by the micromagnet induce the rotation of the spin.