Quantum-nondemolition measurements using ghost transitions

Klaus M. Gheri (1) , Philippe Grangier (2) , Jean-Philippe Poizat (2) , Daniel F. Walls (3)

1 Department of Physics [Auckland]
2 Laboratoire Charles Fabry de l'Institut d'Optique / Optique quantique
3 University of Colorado [Boulder]

We present a detailed analysis of the quantum-nondemolition (QND) properties of a measurement scheme employing coherently driven three-level atoms in the Λ or cascade configuration inside an optical cavity. We propose to use a strong signal field to empty one of the transitions and dress the signal-transition levels. The atoms become transparent for the signal beam, which sees a ''ghost transition.'' When a probe is applied and tuned to the vicinity of one of the light-shifted levels, the probe phase is extremely sensitive to fluctuations of the signal intensity. This enhances the QND coupling and enables the system to operate at lower cooperativities.

Domains: Quantum Physics [quant-ph]

Klaus M. Gheri, Philippe Grangier, Jean-Philippe Poizat, Daniel F. Walls. Quantum-nondemolition measurements using ghost transitions. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 1992, 46, pp.4276-4285. ⟨10.1103/PhysRevA.46.4276⟩. ⟨hal-00559005⟩