A renewed interest in Ge has been sparked by the prospects of exploiting its lower effective mass and higher hole mobility to improve the performance of transistors. Ge emerges also as a promising material in the field of spin qubits, as its coherence times are expected to be very long. Finally, it has been proposed that strained Ge nanowires show an unusually large spin orbit interaction, making them thus suitable for the realization of Majorana fermions. In view of these facts, one is able to envision a new era of Ge in information technology.
The growth of Ge nanocrystals on Si was reported for the first time in 1990. This created great expectations that such structures could provide a valid route towards innovative, scalable and CMOS-compatible nanodevices. Two decades later the PI was able to realize the first devices based on such structures. His results show that Ge self-assembled quantum dots display a unique combination of electronic properties, i.e. low hyperfine interaction, strong and tunable spin-orbit coupling and spin selective tunneling. In 2012, the PI’s group went a step further and realized for the first time Ge nanowires monolithically integrated on Si substrates, which will allow the PI to move towards double quantum dots and Majorana fermions. In view of their exceptionally small cross section, these Ge wires hold promise for the realization of hole systems with exotic properties.
Within this project, these new wires will be investigated, both as spin as well as topological qubits. The objective of the present proposal is mainly to: a) study spin-injection by means of normal and superconducting contacts, b) study the characteristic time scales for spin dynamics and move towards electrical spin manipulation of holes, c) observe Majorana fermions in a p-type system. The PI’s vision is to couple spin and topological qubits in one “technological platform” enabling thus the coherent transfer of quantum information between them.
Fields of science
- natural sciencesphysical scienceselectromagnetism and electronicsspintronics
- natural sciencesphysical sciencestheoretical physicsparticle physicsfermion
- engineering and technologyelectrical engineering, electronic engineering, information engineeringelectronic engineeringcomputer hardwarequantum computer
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