Quantum metrology aims to use entanglement and other quantum resources to improve precision measurement, resulting in Heisenberg limited sensitivity. However, theory suggests that interactions among particles may allow scaling beyond this limit. This study proves experimentally that this can occur in a nonlinear, non-destructive measurement of the magnetization of an atomic ensemble. The work shows that interparticle interactions could be a useful resource for quantum metrology, although the relative performance of nonlinear versus linear measurements has yet to be explored more generally.
- M. Napolitano
- M. Koschorreck
- M. W. Mitchell
