REALIZATION OF A PARADIGM FOR QUANTUM MEASUREMENTS - THE SQUEEZED-LIGHT BEAM SPLITTER

A beam splitter is the simplest and dearest example of a coupling devi ce with which quantum limited measurements can be performed. The limit ations due to the vacuum fluctuations entering the usually unused port are circumvented by injection of a 3.7 dB squeezed wave into this por t. Thereby phase-sensitive measurements that satisfy the quantum nonde molition criteria are realized (signal transfer T-s + T-m = 1.29, 32% correlation). The dependences of the signal transfer and correlation o n beam splitter transmissivity are measured and found to be in quantit ative agreement with a calculation that takes into account various ine fficiencies. Continuous stable operation for 36 hours is achieved.