Quantum metrology

The shift of the definition of the kilogram in 2019 away from an artefact to one relying on the Planck constant inspires technological innovation, as Naoki Kuramoto elucidates.

Tiny quantities of heat delivered on demand by discrete quantum excitations expand the horizon of quantum electrical metrology.

Entanglement can provide an extra boost in precision, but entangled states are hard to detect. A recent experiment solves this problem by letting the entangling dynamics come full circle — or not, depending on the subtle perturbation to be sensed.

A network of quantum sensors for estimating phase shifts is shown to operate with superior sensitivity when delocalized highly entangled states are employed.

Squeezed light is useful for metrology and quantum information. An optomechanical squeezed light source that works at room temperature will facilitate the technological applications of quantum light.