Abstract

Semiconductor quantum dots (QDs) are fascinating systems for potential applications in quantum information processing and communication, since they can emit single photons and, under certain conditions, polarisation entangled photons pairs on demand. The asymmetry and inhomogeneity of real QDs has driven the development of a universal and fine post-growth tuning technique. In parallel, new growth methods are desired to create QDs with high emission efficiency and to control combinations of closely spaced QDs, so-called “QD molecules” (QDMs).

These systems are crucial for the realisation of a scalable information-processing device after a tuning of their interaction energies. In this talk, a growth method based on the infilling of droplet etched nanoholes for obtaining high optical quality and widely tuneable emission wavelength GaAs/AlGaAs QDs and for controlling the lateral formation of InGaAs QD pairs is shown. A novel sample structure permits the light hole to be switched to the ground state by elastically stressing an initially unstrained GaAs QD.

Then, the first device allowing the QD and QDM emission properties to be engineered by large strain and electric fields is presented. This is obtained by integrating diode‐like nanomembranes onto piezoelectric actuators containing single SK-InGaAs/GaAs QDs and QDMs. The two external fields allow the generation of entangled photons by a universal recovery of the QD symmetry and the coupling strength in vertically aligned QDMs to be actively tuned. These results are relevant for the creation and control of entangled states and may enable controlled quantum operations.