CEA Shows Path to Creating Building Blocks of Quantum Processors with 28Si Isotope in a CMOS Fab Line

Fabrication of Isotopically Enriched, Industry-Compatible Wafers Points Way To Realizing Silicon Spin Quantum Bits with Enhanced Fidelity

GRENOBLE, France , Mar. 20, 2018 – 

CEA-Leti, a French technology research institute of the CEA and Inac, a joint fundamental research institute between the CEA and the University Grenoble Alpes, today announced a breakthrough towards large-scale fabrication of quantum bits, or qubits, the elementary bricks of future quantum processors. They demonstrated on a 300 mm pre-industrial platform a new level of isotopic purification in a film deposited by chemical vapor deposition (CVD). This enables creating qubits in thin layers of silicon using a very high purity silicon isotope, ²⁸Si, which produces a crystalline quality comparable to thin films usually made of natural silicon.

"Using the isotope ²⁸Si instead of natural silicon is crucial for the optimization of the fidelity of the silicon spin qubit," said Marc Sanquer, a research director at Inac. "The fidelity of the spin qubit is limited to small values by the presence of nuclear spins in natural silicon. But spin qubit fidelity is greatly enhanced by using ²⁸Si, which has zero nuclear spin. We expect to confirm this with qubits fabricated in a pre-industrial CMOS platform at CEA-Leti."

Qubits are the building blocks of quantum information. They can be made in a broad variety of material systems, but when it comes to the crucial issue of large-scale integration, the range of possible choices narrows significantly. Silicon spin qubits have a small size and are compatible with CMOS technology. They therefore present advantages for large-scale integration compared to other types of qubits.