Single-electron charge sensing in self-assembled quantum dots

TL;DR

This paper demonstrates single-electron charge sensing in self-assembled quantum dots, enabling real-time detection of electron tunneling, which is crucial for quantum information and optoelectronic applications.

Contribution

It introduces a novel charge sensing method for self-assembled quantum dots, previously developed only for gate-defined dots, advancing quantum measurement techniques.

Findings

Successful charge sensing in self-assembled quantum dots

Real-time detection of single-electron tunneling events

Significant current change when electron number varies by one

Abstract

Measuring single-electron charge is one of the most fundamental quantum technologies. Charge sensing, which is an ingredient for the measurement of single spins or single photons, has been already developed for semiconductor gate-defined quantum dots, leading to intensive studies on the physics and the applications of single-electron charge, single-electron spin and photon-electron quantum interface. However, the technology has not yet been realized for self-assembled quantum dots despite their fascinating quantum transport phenomena and outstanding optical functionalities. In this paper, we report charge sensing experiments in self-assembled quantum dots. We choose two adjacent dots, and fabricate source and drain electrodes on each dot, in which either dot works as a charge sensor for the other target dot. The sensor dot current significantly changes when the number of electrons in the target dot changes by one, demonstrating single-electron charge sensing. We have also demonstrated real-time detection of single-electron tunnelling events. This charge sensing technique will be an important step towards combining efficient electrical readout of single-electron with intriguing quantum transport physics or advanced optical and photonic technologies developed for self-assembled quantum dots.