Engineering the properties of epitaxial quantum dots for quantum photonics

Semiconductor quantum dots (QDs) obtained by epitaxial growth are regarded as one of the most promising solid-state sources of triggered single and entangled photons for applications in emerging quantum technologies.
While most of the studies presented so far have mostly focused on InGaAs/GaAs QDs obtained by the Stranski-Krastanow (SK) growth mode, GaAs QDs in AlGaAs matrix have emerged as a promising alternative to SK QDs.
In this talk I will begin by briefly discussing the growth of GaAs QDs with highly symmetric shape  [1] using two independent molecular beam epitaxy machines. I will then present recent results on the generation of high-quality single- and polarization-entangled photons from such dots using resonant two-photon excitation [2]. The good degree of indistinguishability of the emitted photons recently allowed us to perform two-photon interference experiments using two independent QDs  [3]. Finally I will show that the addition of strain after growth not only allows the emission energy and other properties to be tuned [4], but also the nature of confined holes in a QD to be modified. In particular, uniaxial stress allows the quantization axis of the QD to be reoriented in the growth plane [5], a configuration particularly suitable for integrated quantum-photonics applications.
 
References
 
[1]        Y. H. Huo, et al. Appl. Phys. Lett. 102, 152105 (2013). Y. Huo et al. Nature Phys. 10, 46 (2014)
[2]         L. Schweickert, et al. Appl. Phys. Lett. 112, 093106 (2018); D. Huber, et al. Nat. Commun. 8, 15506 (2017); D. Huber et al. arxiv.org/abs/1801.06655
[3]         M. Reindl, et al. Nano Lett. 17, 4090 (2017).
[4]         R. Trotta, et al. Nature Comm. 7, 10375 (2016).
[5]         X. Yuan, et al. https://arxiv.org/abs/1710.03962.
 
About the research of the speaker: https://www.jku.at/hfp/content/e184015/e183740/index_eng.html?team_view=section&t=3&emp=e184015/e183740/employee_groups_wiss184009/employees184010