Single quantum dot standard for confocal detection efficiency

Accurately measuring the detection efficiency of confocal microscopes is crucial for assessing performance, yet it remains challenging. Here, we present a rapid, quantitative method that leverages the photoluminescence of a single quantum dot. By analyzing the cross-correlation of photon arrival times from single exciton and biexciton states, we can precisely determine the detection efficiency. This approach takes less than 30 seconds, is highly tolerant of laser power variations, and does not require calibration procedures. This standard provides a convenient benchmark for routine optimization and reliable cross-laboratory comparisons, establishing a crucial foundation for quantitative fluorescence imaging and the advancement of super-resolution microscopy.