It is impossible to picture modern life without thinking of the vast amount of microelectronic applications that surround us. However, such development has only become possible with the invention of the transistor in the 1950’s. This – back at that time – few centimeters large device, led to a technological revolution. Today the size of the transistors has been shrunk to 7nm where quantum physics comes into play. Researchers are now developing new concepts and techniques using quantum mechanics to allow information processing to operate on completely different principles and to create a quantum computer.
In this line, Loss and DiVincenzo suggested in 1998 the use of electron spins confined in lithographically defined quantum dots as elementary qubits to realize a quantum computer. In the past few years, holes in Germanium have emerged as a very promising platform for the realization of these spin qubits, due to their small effective mass and large spin orbit coupling and absence of the valley problem faced by non-confined electron spins. In addition, in the quantum information community there has been recently a huge wave of excitement about the prospect of using protected qubits for quantum computation. Such protection can be realized on the hardware-level by using topological qubits or cleverly designed electrical circuits.
In the nanoelectronics group, we study spin qubits in two-dimensional Germanium heterostructures and in parallel, we aim to understand whether protected qubits can be realized in hybrid semiconductor-superconductor systems. 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.
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Research Technician/Electrical Eng.
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Jaime Saez Mollejo
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Towards hole spin qubits and Majorana fermions in Germanium | Hybrid semiconductor-superconductor quantum devices | Hole spin orbit qubits in Ge quantum wells | Towards scalable hut wire devices | Topologically protected and scalable quantum bits
Jirovec D, Mutter PM, Hofmann AC, Crippa A, Rychetsky M, Craig DL, Kukucka J, Martins F, Ballabio A, Ares N, Chrastina D, Isella G, Burkard G, Katsaros G. 2022. Dynamics of hole singlet-triplet qubits with large g-factor differences. Physical Review Letters. 128(12), 126803. View
Jirovec D. 2021. Singlet-Triplet qubits and spin-orbit interaction in 2-dimensional Ge hole gases. View
Jirovec D, Hofmann AC, Ballabio A, Mutter PM, Tavani G, Botifoll M, Crippa A, Kukucka J, Sagi O, Martins F, Saez Mollejo J, Prieto Gonzalez I, Borovkov M, Arbiol J, Chrastina D, Isella G, Katsaros G. 2021. A singlet triplet hole spin qubit in planar Ge. Nature Materials. 20(8), 1106–1112. View
Valentini M, Peñaranda F, Hofmann AC, Brauns M, Hauschild R, Krogstrup P, San-Jose P, Prada E, Aguado R, Katsaros G. 2021. Nontopological zero-bias peaks in full-shell nanowires induced by flux-tunable Andreev states. Science. 373(6550), 82–88. View
Aggarwal K, Hofmann AC, Jirovec D, Prieto Gonzalez I, Sammak A, Botifoll M, Martí-Sánchez S, Veldhorst M, Arbiol J, Scappucci G, Danon J, Katsaros G. 2021. Enhancement of proximity-induced superconductivity in a planar Ge hole gas. Physical Review Research. 3(2), L022005. View
ReX-Link: Georgios Katsaros
since 2022 Professor, Institute of Science and Technology (ISTA), Austria
2016 – 2022 Assistant Professor, Institute of Science and Technology (ISTA), Austria
2012 – 2016 Group Leader, Johannes Kepler University, Linz, Austria
2011 – 2012 Group Leader, Leibniz Institute for Solid State and Materials Research, Dresden, Germany
2006 – 2010 Postdoc, CEA, Grenoble, France
2006 PhD, Max Planck Institute for Solid State Research, Stuttgart, Germany
2001 – 2002 Research Assistant, National Center for Scientific Research “Demokritos”, Athens, Greece
2015 Elected member of the Young Academy of the Austrian Academy of Sciences (ÖAW)
2013 ERC Starting Grant
2013 FWF START Award
2012 FWF Lise Meitner Fellowship
2011 Marie Curie Carrier Integration Grant