The Standard Quantum Limit (SQL) in interferometric displacement measurement imposes a restriction on the precision of the measurement due to its quantum back-action noise. This limit can be surpassed over a broad frequency band by injecting squeezed vacuum states with a frequency dependent (FD) quadrature angle into the measurement system. Here, we demonstrate the generation of FD squeezed vacuum states by utilizing Einstein-Podolsky-Rosen (EPR) entangled states. The frequency dependence of the squeezed state can be tuned by conditionally filtering the measurement once the two entangled fields are detected. A stable control scheme for the method is demonstrated which can be implemented in future gravitational-wave detectors to improve their astronomical reach.
@article{arxiv.1908.08685,
title = {Generation and control of frequency dependent squeezing via EPR entanglement},
author = {Min Jet Yap and Paul Altin and Terry G. McRae and Robert L. Ward and Bram J. J. Slagmolen and David E. McClelland},
journal= {arXiv preprint arXiv:1908.08685},
year = {2019}
}