Silicon CMOS quantum bits based on purified Si28

Published : 15 July 2019

We have developed a silicon CMOS spin quantum bit, fabricated in an industrial facility with CEA-Leti. A big effort is currently being devoted towards coupling and scaling-up the number of qubits. Yet an important task remains to improve the properties of single-gate quantum bits, most notably in terms of coherence.

The main source of decoherence is nowadays identified as coming from the nuclear spins carried by the only isotope of silicon which has non-zero nuclear spins, namely 29Si, which accounts for approximately 5% of natural silicon.

For that reason recently fabricated 28Si enriched samples will be available from the start of the PhD. With this isotopic purification we hope to improve significantly the coherence properties.

The main work will consist in measuring the coherence properties and their variability and identify the decoherence mechanisms and suggest ways to suppress them.

This work will be carried out in a new cryo-free dilution refrigerator devoted to these studies, installed in a new laboratory.

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