Quantum twin interferometers

Quantum-correlated interferometer is an emerging tool in quantum technology that offers classical-limit-breaking phase sensitivity. However, to date, there exists a configurational bottleneck for its practicability due to the low phase-sensing power limited by the current detection strategies. Here, we establish an innovative development termed as "quantum twin interferometer" with dual pairs of entangled twin beams arranged in the parallel configuration, allowing full exploitation of the quantum resource through the configuration of entangled detection. We observe the distributed phase sensing with 3-decibel quantum noise reduction in phase-sensing power at the level of milliwatts, which advances the record of signal-to-noise ratio so far achieved in photon-correlated interferometers by three orders of magnitude. The developed techniques in this work can be used to revolutionize a diversity of quantum devices requiring phase measurement.