Non-Traditional Interferometers for Quantum Metrology

We will discuss a new type of interferometers that employ nonlinear devices as beam splitters. A specific scheme with parametric amplifiers, the so called SU(1,1) interferometer, is implemented and iscompared with a traditional linear interferometer. A new paradigm for quantum interferometry is found that is different from the noisereduction mechanism in squeezed state interferometry. Furthermore, thenonlinear process allows the coupling of different types of waves and leads to hybrid interferometry involving different waves. A specificatom-light hybrid interferometer will be discussed.