Device and method for quantum nondemolition measurements using parametric oscillation

摘要

Quantum nondemolition measurements are made by back-action evasion obtained by a combination of a parametric oscillation and a conversion of polarizations. A polarization converter (14, 16, 17), such as a Faraday rotator, converts at substantially a single frequency between at least a portion of a signal polarization state and a detector polarization state. A parametric amplifier (11) having a gain G is coupled to the polarization converter (14, 16, 17).