Amazing stuff! This could be huge!
"Now ... researchers have developed a diamond-based quantum sensor that reveals rich new information about magnetic phenomena at this minute scale. The technique uncovers fluctuations that are beyond the reach of existing instruments and provides key insight into materials such as graphene and superconductors. Superconductors have enabled today’s most advanced medical imaging tools and form the basis of hoped-for technologies like lossless power lines and levitating trains. ...
the team reported roughly 40-times greater sensitivity than previous techniques. ...
That enables unprecedented measurement and reveals details about magnetic fluctuations that hide in the statistical data of more conventional approaches. ...
Her team’s new technique is based on engineered defects near the surface of a lab-grown diamond. These diamonds, about the size of a large flake of sea salt ... one missing atom in a lattice of billions. But because those defects interact strongly with magnetic fields, and because they can be carefully engineered, they make excellent magnetic sensors.
Typically, these sensors are treated as individual points in space. In this latest advance, de Leon and her team built a system that implants two of these defects extremely close together, allowing the defects to interact in quantum-mechanical ways ..."
From the abstract:
"Nitrogen vacancy (NV) centres in diamond are widely deployed as local magnetic sensors, using single-qubit control to measure both time-averaged fields and noise with nanoscale spatial resolution1.
Moving beyond single qubits to multi-qubit control enables new sensing modalities such as measuring nonlocal spatiotemporal correlators or using entangled states to enhance measurement sensitivity.
Here we describe protocols for using optically unresolved NV centre pairs and nuclear spins as multi-qubit sensors for measuring correlated noise at nanometre length scales.
For noninteracting NV centres, we implement a phase-cycling protocol that disambiguates magnetic correlations from variance fluctuations, leveraging the presence of a third qubit, a 13C nucleus, to effect coherent single-NV spin flips and enable phase cycling even for co-aligned NV centres that are spectrally unresolved. For length scales around 10 nm, we create maximally entangled Bell states through dipole–dipole coupling between two NV centres and use these entangled states to directly read out the magnetic field correlation, rather than reconstructing it from independent measurements of unentangled NV centres.
Importantly, this changes the scaling of sensitivity with readout noise from quadratic to linear.
For conventional off-resonant readout of the NV centre spin state (for which the readout noise is roughly 30 times the quantum projection limit), this results in more than an order of magnitude improvement in sensitivity. Finally, we demonstrate methods for detecting high spatial- and temporal-resolution correlators with pairs of strongly interacting NV centres."
Multi-qubit nanoscale sensing with entanglement as a resource (no public access)
Multi-qubit nanoscale sensing with entanglement as a resource (preprint, open access)
Credits: Quantensensor zeigt Magnetfelder, die bisher niemand sehen konnte "Neue Quantensensor-Technologie nutzt verschränkte Diamant-Defekte, um unsichtbare magnetische Phänomene in Supraleitern und Graphen zu messen."
Nathalie de Leon, a leader in diamond-based quantum sensing technologies, led the development of a technique that uncovers previously invisible magnetic fluctuations that are key to understanding quantum materials like graphene and superconductors.
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