Project: Superconducting Silicon Qubit in CMOS Technology

Acronym	SiQUOS
Duration	01/04/2022 - 31/03/2025
Project Topic	Quantum technology for quantum computing builds on a deep understanding of the fundamental phenomena underlying the quantum properties as well as of the phenomena limiting the qubit performance. In addition, the chosen materials need to offer a real potential of scalability and reproducibility, as in the case of silicon and CMOS compatible materials. The aim of SIQUOS is to realise and study a Si gatemon qubit, a gate tuneable transmon qubit composed of a Si Josephson field-effect transistor (JoFET) coupled to a microwave resonator. It represents a valid integrable and scalable alternative to fully metallic superconducting qubits. SIQUOS will focus on the Si JoFET, i.e., a Si transistor with superconducting source and drain (S&D) contacts, whose non-dissipative supercurrent can be modulated by an electrostatic gate. CMOS-compatible metal silicides and heavily boron (B) doped Si will be used as the superconducting S&D contacts. A comprehensive investigation of the superconductor/Si (S/Sm) interface by means of structural, chemical and low-temperature electronic transport characterisation will be performed. The first and foremost objective of SIQUOS is to optimise the S/Sm interface transparency so as to allow for the transfer of correlated charge carriers from the superconducting contacts into the Si channel and to reach large, reproducible supercurrents. The second objective is to realise superconducting Si transistors, demonstrating the gate tuneability of the Josephson supercurrent. Thereupon, the third and final objective is to integrate Si JoFETs in a transmon geometry including on-chip capacitors and resonators, and to realise the manipulation of quantum states in Si-gatemon devices. Additionally, the quantum performance of individual qubits will be measured when coupled to a limited number of other qubits to anticipate more complex quantum circuits. The control of the qubit properties in a scalable technology, and therefore the potential to directly assemble a large number of qubits in a functional quantum circuit, is an added major outcome of the project. To achieve its successful realisation, SIQUOS relies on a multidisciplinary consortium with expertise in material and characterisation science, process integration and quantum nanoelectronics.
Network	QuantERA II
Call	QuantERA II Call 2021

Project partner

Number	Name	Role	Country
1	Photonique Electronique et Ingénierie Quantiques	Coordinator	France
2	Centre de Nanosciences et de Nanotechnologies	Partner	France
3	/ Centre for Energy Research (EK) / Institute for Technical Physics and Materials Science (MFA)	Partner	Hungary
4	Uppsala University	Partner	Sweden