C04 Ultrafast electric control of optical polarizations and transitions

Alex Widhalm, AG Zrenner

What is the challenge of my research project? Why am I eager to do it?
Since the beginning of the first funding period of the TRR142 I have been involved in the project C04, first as a PhD student and now as a Postdoc. In this project, I investigate ultrafast electrical control of optical properties and transitions of semiconductor nanostructures. The focus of my research is the interaction of very short electrical pulses in the picosecond time range (10^-12 seconds) with equally short laser pulses in zero-dimensional nanostructures, called quantum dots in III/V semiconductors. Therefore we develop novel electric circuits based on SiGe BiCMOS technology and apply them in quantum interference experiments such as Ramsey interference. This unique combination of optical and electrical pulses enables coherent optoelectronic control of exciton quantum bits.

Why did I choose this project?
My project requires a high degree of technological development for the realization of the experiments, from the design of ultrafast electrical circuits to the fabrication of low capacitance quantum dot photodiodes. This strong and challenging focus on technology was also one of the reasons why I am so enthusiastic about this project. In my opinion, coherent optoelectronics is a promising concept towards scalable quantum technologies.