2012/11/15 by S. Steinlechner, Steinlechner, Sebastian, J. Bauchrowitz +9 · 3 citations
Physics and Astronomy · #Advanced Frequency and Time Standards #Cold Atom Physics and Bose-Einstein Condensates #FOS: Physical sciences #Pulsars and Gravitational Waves Research #Quantum Physics (quant-ph)
paper · pdf · doi:10.48550/arxiv.1211.3570
openalex publication_date 2012/11/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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.