Fig. 1: Resonant excitation of the nanowire quantum dot.
From: Oscillating photonic Bell state from a semiconductor quantum dot for quantum key distribution
a Illustration of the InAsP quantum dot (QD) in an InP tapered nanowire waveguide, which emits the biexciton (XX) and exciton (X) into the same Gaussian mode. b Illustration of two-photon resonant excitation (TPRE) generating a biexciton in the QD. The intermediate exciton energy level has a finite fine structure splitting (S) between the H-polarized (XH) and the V-polarized (XV) states. c The emission spectrum from the nanowire QD under π-pulse TPRE. Exciton and biexciton emission lines are located at 893.25 nm and 894.67 nm, respectively. The small central peaks are from remnants of the filtered laser pulse midway between X and XX. We observe a small contribution from the negatively charged exciton (X−). d Biexciton and exciton state population as a function of pulse area where a pulse area of π corresponds to the maximum population. The dots represent experimental data and the solid curves are the fitted curves (see Supplementary Note 1). e Hanbury-Brown-Twiss autocorrelation measurements of both the X and XX emission, demonstrating low multi-photon emission probability.
