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Deep-level modeling of novel germanium-based superconductive quantum devices

Project description

Germanium-based superconductive devices for quantum computation

One of the greatest challenges in quantum computing is engineering scalable quantum devices. Proximity-induced superconductivity is crucial in many quantum technologies, but commonly used III-V semiconductors are unsuitable for spin-based qubits due to their large hyperfine interaction. Germanium, however, presents a promising alternative – it supports proximity-induced superconductivity, has strong spin-orbit coupling, and can be nearly nuclear-spin free. Supported by the Marie Skłodowska-Curie Actions programme, the GeSuperQuant project aims to uncover the mechanisms behind superconducting proximity effects in germanium. By developing advanced theoretical models, the project will predict key properties, such as spin-orbit coupling and g-factors, in superconducting quantum devices. This research could pave the way for a new type of qubit, unlocking fresh possibilities for quantum computing.

Objective

A great scientific and technical challenges of our time is to engineer a scalable quantum computer, and proximity-induced superconductivity is one of the most important ingredients in many quantum devices. Proximitized III-V semiconductors can host a hard superconducting gap and have been vastly studied in super-semi quantum devices. Nevertheless, these material compounds are not suitable for spin-based qubits due to their large hyperfine interaction and are hence not ideal for use in hybrid devices. One of the most promising, but so far unexplored researched materials to use in such hybrid quantum devices is germanium: it is a potentially ideal host for proximity-induced superconductivity, and exhibits a hard superconducting gap, but can also be used for spin-based qubits since it has suppressed hyperfine interaction and can be isotope purified to be nearly nuclear-spin free. Additionally, it has an exceptionally large hole mobility, strong intrinsic spin-orbit coupling, as well as tunable g-factors, making it an ideal material to use in quantum devices. However, the mechanism for the superconducting proximity effect in germanium is still unknown.
In this project I will develop band models based on atomistic orbitals (kp theory), and combine them with T-matrix methods from Greens function theory, to show what mechanisms are responsible for proximity induced superconductivity in the hole bands of germanium. I will apply the results to g-factor dependent Andreev spin qubits and phase- and gate-tunable long-range spin-qubit couplers. I will predict effective spin-orbit coupling and g-factors in these superconducting quantum devices, using effective low-energy models (discretized on a lattice) to predict outcomes of future experiments on germanium-based quantum information devices. This will open up a new avenue of research, through the development of a new type of qubit.

Fields of science (EuroSciVoc)

Keywords

Programme(s)

Topic(s)

Funding Scheme

HORIZON-TMA-MSCA-PF-EF - HORIZON TMA MSCA Postdoctoral Fellowships - European Fellowships

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Call for proposal

(opens in new window) HORIZON-MSCA-2024-PF-01

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Coordinator

KOBENHAVNS UNIVERSITET
Net EU contribution
€ 263 393,28
Address
NORREGADE 10
1165 KOBENHAVN
Denmark
Region
Danmark Hovedstaden Byen København
Activity type
Higher or Secondary Education Establishments
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Total cost
No data