SIQUOS, Superconducting Silicon Qubit in CMOS Technology

The aim of SIQUOS is to realise a Si gatemon qubit, i.e. 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. The Si JoFET is a Si transistor with superconducting source and drain (S&D) contact.

Its non-dissipative supercurrent can be modulated by an electrostatic gate. CMOS-compatible metal silicides and heavily 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 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 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.

To achieve its successful realisation, SIQUOS involves a multidisciplinary consortium with expertise in material and characterisation science, process integration and quantum nanoelectronics.