Date and Time:  1-July-2022  16:00

Speaker:  Dr. Santanu Manna, Johannes Kepler University Linz, Austria

Host: Quanyong Lu(BAQIS）

Title:  GaAs quantum dots grown by droplet etching epitaxy as quantum light sources

Abstract: 

World is now heavily dependent on semiconductor devices; Si is leading the microelectronics industry and III-V compound semiconductors for light sources. Because of the indirect bandgap, Si can’t compete with direct bandgap III-V semiconductors regarding light emission, whether its classical or quantum. GaAs and InP are mostly studied III-V platforms for the same. In my talk, I will concentrate on GaAs quantum dots regarding its applications for single/entangled quantum emitters (~780 nm), which is a very hot topic now. Since this is a lattice matched case, typical Stranski-Krastanov growth method is unnecessary here and droplet method appears into the picture. Using droplet etching of nanoholes followed by GaAs filling, strain-free as well as highly symmetric dots could be produced and this system can generate single photon as well as entangled photons. Next, I will show that the p-i-n diode structure containing GaAs QD can overcome blinking issue, and that could be useful for achieving high visibility of two-photon interference from two different remote dots to establish quantum network and computing schemes and also enhancing the key rates in quantum key distribution. Lastly, I would describe the present research trend in the community which concerns moving from ~780 or ~900 nm to telecom C-band entangled photon emitters. 

About the Speaker:

Santanu Manna received both Masters and PhD Degree in Physics from Indian Institute of Technology Kharagpur, India in 2008 and 2014, respectively. As a visiting postdoc fellow, he joined the NanoLab in the Department of Physics, University of Trento, Italy to work with Prof. Lorenzo Pavesi on silicon photonics during 2014-2015. Later on, he joined the Center for Quantum Devices, ECE Department, McCormick School of Engineering in Northwestern University, United States as a postdoctoral fellow to work on InP based quantum cascade lasers with Prof. Manijeh Razeghi during 2016-2018. Later on, he joined the Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Austria as a postdoctoral researcher in 2018 to work with Prof. Armando Rastelli on III-V quantum dot based single/entangled photon emitters and he is now a university assistant in the same place. In a nutshell, his research interest lies in the epitaxial growth by molecular beam epitaxy, processing and measurements on III-V semiconductor (GaAs, InP) based quantum devices like single/entangled photon emitters for quantum communication, quantum cascade laser based frequency comb and THz emitter for recognizing different molecular fingerprints. Presently he is working on blinking-free quantum dot as entangled photon source for quantum key distribution. Till now he has published more than 40 international journal articles; he is the recipient of the prestigious ‘University Assistant’ position in the JKU Linz; he has been recently offered an ‘Assistant Professor’ position in the prestigious IIT Delhi, India and also awarded ‘Young faculty incentive fellowship’.