Quantum-Optically Resolving the Number of Colloidal Quantum Dots in a Subwavelength Volume

TL;DR

This paper introduces a quantum optical method to accurately count the number of colloidal quantum dots within a subwavelength volume by analyzing photon correlations, enabling non-invasive quantification of artificial atoms.

Contribution

It presents a novel time-domain quantum optical technique for strict enumeration of quantum dots in nanoscale volumes, based on superradiance and photon correlation analysis.

Findings

Successfully counts quantum dots from one to ten within a subwavelength volume.

Provides an analytic relation linking photon correlation to emitter number and lifetime.

Demonstrates a non-invasive approach for quantum emitter quantification at the nanoscale.

Abstract

The number resolution of solid-state artificial atoms is of fundamental interest for the study of quantum few-body systems, yet remains experimentally challenging. Quantum optical experiments offer a non-invasive approach which links up macroscopic measurements with the quantity of quantum emitters. In this work, we propose a time-domain quantum optical methodology for the strict numbering of colloidal CdSe/CdS/ZnS quantum dots (QDs) confined in subwavelength-size polystyrene capsules. The non-polarized, homogeneously broadened emission of colloidal QDs in the subwavelength volume satisfies the description of Dicke's superradiance of identical quantum emitters. An analytic relation describes the numerical dependence of the second-order photon correlation on the number and the collective lifetime of emitters, yielding an experimental counting range of colloidal QDs from one to ten. This work provides a robust pathway for the non-invasive numbering of artificial atoms and the investigation of collective light-matter interactions at the nanoscale.