Dark Matter Direct Detection with Quantum Dots

TL;DR

This paper proposes using quantum dots as novel, tunable targets for detecting sub-GeV dark matter-electron interactions, leveraging their scintillation properties and commercial availability to improve detection sensitivity.

Contribution

It introduces quantum dots as a new detection medium for dark matter, detailing their properties and how they can be used with existing photodetectors to enhance detection capabilities.

Findings

Quantum dots can generate detectable electron-hole pairs upon dark matter interaction.

A simple experimental setup with quantum dots and PMTs can surpass current dark matter detection bounds.

Using low dark-count photodetectors can significantly improve detection sensitivity.

Abstract

We propose using Quantum Dots as novel targets to probe sub-GeV dark matter-electron interactions. Quantum dots are nanocrystals of semiconducting material, which are commercially available, with gram-scale quantities suspended in liter-scale volumes of solvent. Quantum dots can be efficient scintillators, with near unity single-photon quantum yields, and their band-edge electronic properties are determined by their characteristic size, which can be precisely tuned. Examples include lead sulfide (PbS) and lead selenide (PbSe) quantum dots, which can be tuned to have sub-eV optical gaps. A dark-matter interaction can generate one or more electron-hole pairs (excitons), with the multi-exciton state decaying via the emission of two photons with an efficiency of about 10% of the single-photon quantum yield. An experimental setup using commercially available quantum dots and two photo-multiplier-tubes (PMTs) for detecting the coincident two-photon signal can already improve on existing dark-matter bounds, while using photodetectors with lower dark-count rates can improve on current constraints by orders of magnitude.