Tunable artificial Atoms: Strain engineered semiconductor Quantum dots

Date

Sep 18, 2015

Time

1:00 PM - 2:00 PM

Speaker

Dr. Fei Ding

Affiliation

IFW Dresden / IIN

Language

en

Main Topic

Materialien

Other Topics

Materialien, Physik

Host

Ulrike Steere

Description

Self-assembled semiconductor quantum dots (QDs), often referred to as artificial atoms, are among the leading candidates for the deterministic generation of quantum light emissions (e.g. single photons and entangled photons). Unlike real atoms or any other quantum light sources, QDs have an undeniable advantage of being compatible with mature semiconductor technologies. Therefore semiconductor QD based quantum photonic devices are expected to play a crucial role in quantum information science. In the first part of my talk a brief overview of the field will be given, with a main focus on the growth of semiconductor InAs/GaAs and GaAs/AlGaAs QDs via molecular beam epitaxy (MBE). Similar to real atoms, QDs can be used to generate single photons due to their discrete energy levels. In our lab, different techniques were developed to fabricate QDs with single photon emission in between 700 nm and 1000 nm. Especially we are interested in QDs emitting single photons at around 780 nm and 895 nm, which are the absorption of rubidium and cesium atomic vapors, respectively. A future prospective is to couple these artificial atoms with real atoms, for a potential application in quantum memory. Unlike real atoms, however, the physical properties of QDs are highly random. This is a serious problem for fabricating QDs based quantum devices where precise controls over the electronic and optical properties are needed. By embedding the QDs in stretchable nanomembranes, our group has developed a unique strain tuning technique to engineer the QDs. [1] In the second part of my talk I will review our recent progresses [2-6] in terms of the realization of controllable quantum light sources. I will start with a wavelength tunable single photon source [2,3,4] and in particular, in the form of a quantum light-emitting-diode (LED). Then I will introduce a hybrid system where the single photon emission from QDs can be tuned to rubidium D2 line at exactly 780.241 nm. Finally I will talk about our efforts in generating entangled photon pairs with QDs. We have fabricated an entangled LED with the fastest operation speed and highest yield ever reported.[5] In future our strain tuning platform will be much more powerful/versatile by using integrated piezoelectric MEMS on a silicon chip.[6] References: [1] F. Ding*, OGS, et al., Phys. Rev. Lett. 104, 067405 (2010) [2] J. Zhang...FD*, OGS, Nano Lett. 13, 5808 (2013) [3] Y. Huo...FD, OGS, et al., Nature Phys. 10, 46 (2014) [4] J. Zhang...FD*, OGS, et al., Nano Lett. 15, 422 (2015) [5] J. Zhang...FD*, OGS, arxiv. 1505.03026, under review. (2015) [6] Y. Chen...FD*, OGS, arxiv. 1508.00042, under review. (2015)

Links

• Seminars at the IFW

Last modified: Sep 18, 2015, 9:44:48 AM