“The technique uncovers fluctuations that are beyond the reach of existing instruments and provides key insight into materials such as graphene and superconductors,” according to the university. “The underlying diamond-based sensing methods have been under development for half a decade. But the team reported roughly 40-times greater sensitivity than previous techniques.”
These are ‘Nitrogen vacancy centre’ sensors, where a nitrogen atom amongst a billion carbon atoms in the diamond’s crystal can be probed to detect local conditions
“Because those defects interact strongly with magnetic fields, and because they can be carefully engineered, they make excellent magnetic sensors,” said Princeton.
A closely-spaced pair of these nitrogen atoms (implanted ~20nm below the surface of a diamond and ~10nm apart) can extract additional information about the local environment, but only if enough data can be gathered to allow number-crunching to remove ambiguity.
The new idea, which came from researcher Jared Rovny during the enforced isolation of the Covid era, was that entangling the two nitrogen atom centres would allow direct read-out of the desired quantity – local magnetic field correlation – with no need to reconstruct correlation from separate measurements on two un-related centres.
“What I realised is, that if you entangled them, the presence or absence of a correlation sort of puts its fingerprint onto the system,” said Rovny.
Published in Nature, the work is described in the paper ‘Multi-qubit nanoscale sensing with entanglement as a resource‘.
Image credit A Khan Fohtobuddy
