Quantum metrology deals with improving the resolution of instruments that are otherwise limited by shot noise and it is therefore a promising avenue for enabling scientific breakthroughs. The advantage can be even more striking when quantum enhancement is combined with correlation techniques among several devices. Here, we present and realize a correlation interferometry scheme exploiting bipartite quantum correlated states injected in two independent interferometers. The scheme outperforms classical analogues in detecting a faint signal that may be correlated/uncorrelated between the two devices. We also compare its sensitivity with that obtained for a pair of two independent squeezed modes, each addressed to one interferometer, for detecting a correlated stochastic signal in the MHz frequency band. Being the simpler solution, it may eventually find application to fundamental physics tests, e.g., searching for the effects predicted by some Planck scale theories.
Bibliographical noteFunding Information:
We acknowledge the “COST Action MP1405 QSPACE,” the European Union’s Horizon 2020, and the EMPIR Participating States in the context of the project 17FUN01 BeCOMe, the John Templeton Foundation (Grant number 43467) for financial support. We also acknowledge the Center for Macroscopic Quantum States (bigQ, DNRF412) of the Danish National Research Foundation and the Danish Council for Independent Research (Individual Postdoc and Sapere Aude 4184-00338B).
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