Enhancement of proximity-induced superconductivity in a planar Ge hole gas

Aggarwal, Kushagra; Hofmann, Andrea; Jirovec, Daniel; Prieto, Iván; Sammak, Amir; Botifoll, Marc; Martí‐Sánchez, Sara; Veldhorst, Menno; Arbiol, Jordi; Scappucci, Giordano; Danon, Jeroen; Katsaros, Georgios

doi:10.1103/physrevresearch.3.l022005

Cited by 36 publications

(16 citation statements)

References 51 publications

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“…S5 (data are for a different SNS-QPC device with identical design to the one presented here). We use the switching current as a lower bound for the critical current and we estimate an I sw R N product of 51 µV, showing an improvement as compared to previous results obtained with pure Al contacts in Ge QWs [31,33], despite the Al T c is higher than the PtSiGe T c .…”

Section: Highly Transparent Josephson Junctionmentioning

confidence: 61%

“…Planar germanium heterostructures are also a compelling candidate for superconductor-semiconductor hybrids: in addition to the strong spin orbit coupling and the high-mobility-crucial for a reliable search of topological superconductivity-holes in germanium have electrically tunable g-factors [23] and can make Schottkybarrier-free contacts to superconductors by pinning of the Fermi level to the valence band [30]. Initial promising work demonstrated tunable supercurrents and high transparency superconductor-semiconductor hybrid devices by using Al to contact the quantum well either via thermal diffusion [22,31] or by etching of the heterostructure [32,33]. Further progress is challenged by the difficult task of contacting uniformly a buried quantum well with a superconductor, whilst maintaining the low disorder at the superconductor-semiconductor interface and in the semiconductor channel.…”

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confidence: 99%

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Hard superconducting gap in a high-mobility semiconductor

Tosato¹,

Levajac²,

Wang³

et al. 2022

Preprint

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The co-integration of spin, superconducting and topological systems is emerging as an exciting pathway for scalable and high-fidelity quantum information technology. High-mobility planar germanium is a front-runner semiconductor for building quantum processors with spin-qubits, but the lack of a pristine interface with a superconductor has slowed progress with hybrid superconductorsemiconductor devices. Here we take this step and demonstrate a low-disorder, oxide-free interface between high-mobility planar germanium and a germanosilicide parent superconductor. This superconducting contact is formed by the thermally-activated solid phase reaction between a metal (Pt) and the semiconductor heterostructure (Ge/SiGe). Electrical characterization reveals near-unity transparency in Josephson junctions, hard induced superconducting gap in quantum point contacts, phase control of a Josephson junction in a superconducting quantum interference device, and a superconducting to insulating transition in gated two-dimensional superconductor-semiconductor arrays. These results expand the quantum technology toolbox in germanium and provide new avenues for exploring monolithic superconductor-semiconductor quantum circuits towards scalable quantum information processing.

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Section: Highly Transparent Josephson Junctionmentioning

confidence: 61%

mentioning

confidence: 99%

Hard superconducting gap in a high-mobility semiconductor

Tosato¹,

Levajac²,

Wang³

et al. 2022

Preprint

Self Cite

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“…There are several candidate materials for the design of quantum calculators. Such materials can be planar Ge/SiGe heterostructures [13,14], germanium hut wires (HW) [15,16], and germanium core-shell nanowires (NW) [17,18]. HW germanium nanowires grown on silicon surfaces are of the greatest interest.…”

Section: Introductionmentioning

confidence: 99%

DFT Analysis of Hole Qubits Spin State in Germanium Thin Layer

2022

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Due to the presence of a strong spin–orbit interaction, hole qubits in germanium are increasingly being considered as candidates for quantum computing. These objects make it possible to create electrically controlled logic gates with the basic properties of scalability, a reasonable quantum error correction, and the necessary speed of operation. In this paper, using the methods of quantum-mechanical calculations and considering the non-collinear magnetic interactions, the quantum states of the system 2D structure of Ge in the presence of even and odd numbers of holes were investigated. The spatial localizations of hole states were calculated, favorable quantum states were revealed, and the magnetic structural characteristics of the system were analyzed.

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“…Holes in germanium nanowires (NWs) are predicted to be a promising platform for spin-qubit-based quantum computing due to their strong spin–orbit interaction (SOI) and low susceptibility to hyperfine interaction. − The strong SOI of holes enables fast and electrical manipulation of qubits, while the low susceptibility to hyperfine interactions ensures long coherence lifetimes. Of particular interest for nanowires is the possibility of tuning the shape and crystal orientation, which can result in the cancellation of the influence of charge noise and hyperfine interaction on coherence .…”

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confidence: 99%

Coherent Hole Transport in Selective Area Grown Ge Nanowire Networks

et al. 2022

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Holes in germanium nanowires have emerged as a realistic platform for quantum computing based on spin qubit logic. On top of the large spin−orbit coupling that allows fast qubit operation, nanowire geometry and orientation can be tuned to cancel out charge noise and hyperfine interaction. Here, we demonstrate a scalable approach to synthesize and organize Ge nanowires on silicon (100)-oriented substrates. Germanium nanowire networks are obtained by selectively growing on nanopatterned slits in a metalorganic vapor phase epitaxy system. Low-temperature electronic transport measurements are performed on nanowire Hall bar devices revealing high hole doping of ∼10 18 cm −3 and mean free path of ∼10 nm. Quantum diffusive transport phenomena, universal conductance fluctuations, and weak antilocalization are revealed through magneto transport measurements yielding a coherence and a spin−orbit length of the order of 100 and 10 nm, respectively.

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Enhancement of proximity-induced superconductivity in a planar Ge hole gas

Cited by 36 publications

References 51 publications

Hard superconducting gap in a high-mobility semiconductor

Hard superconducting gap in a high-mobility semiconductor

DFT Analysis of Hole Qubits Spin State in Germanium Thin Layer

Coherent Hole Transport in Selective Area Grown Ge Nanowire Networks

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