Autocorrelation analysis for the unbiased determination of power-law exponents in single-quantum-dot blinking

TL;DR

This paper introduces an unbiased autocorrelation analysis method to accurately determine power-law blinking exponents in single quantum dots, overcoming limitations of threshold-based techniques and enabling microsecond timescale analysis.

Contribution

The authors develop a robust autocorrelation-based approach that extracts blinking exponents without threshold discrimination, achieving high precision even in low signal-to-noise conditions.

Findings

Accurately determines ON and OFF power-law exponents with 3% precision.

Works effectively with shot-noise-dominated signals below 1 photon per frame.

Enables threshold-free analysis at microsecond timescales.

Abstract

We present an unbiased and robust analysis method for power-law blinking statistics in the photoluminescence of single nano-emitters, allowing us to extract both the bright- and dark-state power-law exponents from the emitters' intensity autocorrelation functions. As opposed to the widely-used threshold method, our technique therefore does not require discriminating the emission levels of bright and dark states in the experimental intensity timetraces. We rely on the simultaneous recording of 450 emission timetraces of single CdSe/CdS core/shell quantum dots at a frame rate of 250 Hz with single photon sensitivity. Under these conditions, our approach can determine ON and OFF power-law exponents with a precision of 3% from a comparison to numerical simulations, even for shot-noise-dominated emission signals with an average intensity below 1 photon per frame and per quantum dot. These capabilities pave the way for the unbiased, threshold-free determination of blinking power-law exponents at the micro-second timescale.