The first true quantum non-demolition measurement of atomic spins by paramagnetic Faraday rotation in a quantum atom–light interface is described. By using an ensemble of 87Rb atoms, quantum state preparation and information–damage trade-off are observed beyond their classical limits by 7 and 12 standard deviations, respectively.
- R. J. Sewell
- M. Napolitano
- M. W. Mitchell
