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ERC

ASCENT Report Summary

Project ID: 279781
Funded under: FP7-IDEAS-ERC
Country: United Kingdom

Final Report Summary - ASCENT (Advanced materials and devices for hybrid spin coherent technologies)

The ASCENT project studied the magnetic moments, or spins, of electrons and nuclei in a variety of molecules and silicon-based devices. The aim was to understand how coherent quantum ‘superpositions’ of such spins (where a spin can point up and down at the same time) could be made to last as long as possible, and couple together to demonstrate entanglement (what Einstein famously called ‘spooky action at a distance’).

In custom-designed molecules, we demonstrated how electron spins, created by exciting the molecule using a laser pulse, could be used to create entanglement between nuclear spins. These techniques could be useful
We also designed, fabricated and studied molecules where two spins are created by a laser pulse and separate to two ends of the molecule. Such molecules are model systems for a theory of how certain animals “see” magnetic fields.

The majority of the project was dedicated to studied spins in silicon. Here, we studied the lifetime of spin superpositions, of both the electron and nuclear spin. We showed how the electron spin superposition states could last for seconds, at particular points called “clock transitions” where they become immune to magnetic field noise. We also showed how nuclear spins could remain in coherent states for up to 3 hours.

We made pioneering studies showing the potential for bismuth donor atoms in silicon as an attractive dopant for quantum technologies, and coupled them to superconducting resonators to show for the first time that spin-relaxation times could be controlled and determined by a microwave cavity. We also extended our results from ensembles of donors to the single-spin level, and identified spins of individual quantum dots and donors present in ‘standard’ nanowire FET devices being developed for next-generation conventional computers.

Finally, we developed and patented an design for a quantum computer based on donor spins in silicon, using the results of the ASCENT project.

The ASCENT project benefitted strongly from several collaborations with internationally-leading research groups, including those from Australia, Canada, France, and the US.

Reported by

UNIVERSITY COLLEGE LONDON
United Kingdom
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