# Heralded spectroscopy reveals exciton-exciton correlations in single colloidal quantum dots

**Authors:** Gur Lubin, Ron Tenne, Arin Can Ulku, Ivan Michel Antolovic, Samuel Burri, Sean Karg, Venkata Jayasurya Yallapragada, Claudio Bruschini, Edoardo Charbon, Dan Oron  
**arXiv:** [2108.00345](https://arxiv.org/abs/2108.00345)  
**Date:** 2021-08-01  
**Summary page:** https://www.summarizepaper.com/en/paper/2108.00345v1/

## Key points

- Study of multiply-excited states in semiconductor quantum dots is important for nanocrystal-based technologies
- Investigating these states through photoluminescence is challenging due to overlap with other emissions
- Biexciton heralded spectroscopy introduced as a solution to directly observe biexciton-exciton emission cascades and measure biexciton binding energy at room temperature
- Technique allows observation of correlations between biexciton binding energy and charge-carrier confinement and fluctuations of local electrostatic potential
- Heralded spectroscopy has potential for extending understanding of charge-carrier dynamics in multielectron systems and parallelization of quantum optics protocols
- Research provides valuable insights into physics of semiconductor quantum dots with implications for future technological advancements.

## Summary

The study of multiply-excited states in semiconductor quantum dots is essential for advancing nanocrystal-based technologies. Investigating these states through photoluminescence has proven challenging due to the temporal and spectral overlap with emission from singly-excited and charged states. To address this issue, the authors introduce biexciton heralded spectroscopy which uses a single-photon avalanche diode array based spectrometer to directly observe biexciton-exciton emission cascades and measure the biexciton binding energy of single quantum dots at room temperature. This technique allows for the observation of correlations between the biexciton binding energy and both charge-carrier confinement and fluctuations of the local electrostatic potential that were previously masked in ensembles. The authors suggest that heralded spectroscopy has great potential for extending our understanding of charge-carrier dynamics in multielectron systems and parallelization of quantum optics protocols. Overall, this research provides valuable insights into the physics of semiconductor quantum dots and could have significant implications for future technological advancements.