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Physics Today

Squeezed light reduces noise at a gravitational-wave observatory

Johanna L. Miller

Published Oct 31, 2011• 5 citations
Publisher

Abstract

A decades-old idea—tinkering with light’s quantum fluctuations to make a large interferometer even more sensitive—has now been implemented.
DOI
10.1063/pt.3.1316

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A fundamental noise source limiting the measurement sensitivity of interferometric gravitational wave (GW) observatories is the light's quantum noise. While the sensitivity of the first observatory generation was limited by the shot noise at Fourier frequencies above several hundred hertz, the future observatory generations are expected to be limited by quantum noise also in their low-frequency detection band. Squeezed states of the light field allow for improving the sensitivity at all quantum-noise-limited frequencies. Recently, a squeezing-reduced shot noise of the GW observatory GEO 600 was demonstrated. Based on this success, the Einstein Telescope design study proposes squeezed-light injection to reduce shot noise as well as quantum radiation pressure noise by a factor of ten in power, i.e. by 10 dB. This contribution summarizes the current state of the art in the field of squeezed-light generation for gravitational wave astronomy and the prospects for the intermediate future.