A nanometer-scale optical electrometer

TL;DR

This paper demonstrates a high-sensitivity optical electrometer using quantum dots, achieving competitive sensitivity levels with potential advantages in bandwidth and efficiency over existing nanometer-scale sensors.

Contribution

It introduces a novel quantum dot-based optical electrometer utilizing homodyne detection for electric field measurement, with detailed analysis of its sensitivity and operational advantages.

Findings

Achieved a sensitivity of 5 V/m/√Hz at 4.2 K.

Demonstrated static and transient electric field detection capabilities.

Sensitivity compares favorably to theoretical limits for single-electron transistors.

Abstract

Self-assembled semiconductor quantum dots show remarkable optical and spin coherence properties, which have lead to a concerted research effort examining their potential as a quantum bit for quantum information science1-6. Here, we present an alternative application for such devices, exploiting recent achievements of charge occupation control and the spectral tunability of the optical emission of quantum dots by electric fields7 to demonstrate high-sensitivity electric field measurement. In contrast to existing nanometer-scale electric field sensors, such as single electron transistors8-11 and mechanical resonators12,13, our approach relies on homodyning light resonantly Rayleigh scattered from a quantum dot transition with the excitation laser and phase sensitive lock-in detection. This offers both static and transient field detection ability with high bandwidth operation and near unity quantum efficiency. Our theoretical estimation of the static field sensitivity for typical parameters, 0.5 V/m/ \surd Hz, compares favorably to the theoretical limit for single electron transistor-based electrometers. The sensitivity level of 5 V/m/ \surd Hz we report in this work, which corresponds to 6.4 * 10-6 e/ \surd Hz at a distance of 12 nm, is worse than this theoretical estimate, yet higher than any other result attained at 4.2 K or higher operation temperature.