Katsaros Group

Nanoelectronics

It is impossible to picture modern life without thinking of the vast amount of microelectronic applications that surround us. However, such development has only been made possible with the invention of the transistor in the 50’s. This – back at that time – few centimeters large device, product of mere scientific curiosity, led to a technological revolution. Today the size of the transistors has been shrunk to less than 14 nm and quantum physics comes into play. Researchers in basic research are trying to develop new concepts which will use quantum mechanics and allow information processing to operate on completely different principles.

In this line, Loss and DiVincenzo suggested the use of electron spins confined in lithographically defined quantum dots as elementary qubits to realize a quantum computer. In the past few years Si and Ge have emerged as very promising hosts for the realization of spin qubits since they can be isotopically purified which can thus lead to very long coherence times. In parallel to the development of spin qubits, there has been recently a huge wave of excitement in the prospect of using topological qubits for quantum computation. Such topological qubits are predicted to be robust versus decoherence. In the main focus of these proposals are the so-called Majorana fermions, introduced by Majorana more than 70 years ago. Various studies have suggested the use of topological insulators and semiconductor nanowires for the realization of Majorana fermions.

In the nanoelectronics group we study spin qubits in Ge based systems, self-assembled nanostructures and lithographically defined QDs in two dimensional hole gases. In parallel we aim to understand whether Majorana fermions can be realized and detected in a hole-type system. Finally, hybrid Al/InAs nanowire devices are studied in order to prove the topological properties of Majorana fermions. While our research is focused on the realization of different types of qubits, the group is very much interested in studying new fundamental physics emerging in semiconductor nanodevices.