Quantum metrology utilizes entanglement for improving the sensitivity of measurements. Up to now the focus has been on the measurement of just one out of two non-commuting observables. Here we demonstrate a laser interferometer that provides information about two non-commuting observables, with uncertainties below that of the meter's quantum ground state. Our experiment is a proof-of-principle of quantum dense metrology, and uses the additional information to distinguish between the actual phase signal and a parasitic signal due to scattered and frequency shifted photons. Our approach can be readily applied to improve squeezed-light enhanced gravitational-wave detectors at non-quantum noise limited detection frequencies in terms of a sub shot-noise veto-channel.
@article{arxiv.1211.3570,
title = {Quantum-Dense Metrology},
author = {Sebastian Steinlechner and Jöran Bauchrowitz and Melanie Meinders and Helge Müller-Ebhardt and Karsten Danzmann and Roman Schnabel},
journal= {arXiv preprint arXiv:1211.3570},
year = {2012}
}
Comments
5 pages, 3 figures; includes supplementary materials