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Published June 2008 | public
Journal Article

A quantum-enhanced prototype gravitational-wave detector

Abstract

The quantum nature of the electromagnetic field imposes a fundamental limit on the sensitivity of optical precision measurements such as spectroscopy, microscopy and interferometry. The so-called quantum limit is set by the zero-point fluctuations of the electromagnetic field, which constrain the precision with which optical signals can be measured. In the world of precision measurement, laser-interferometric gravitational-wave detectors, are the most sensitive position meters ever operated, capable of measuring distance changes of the order of 10- 18 m r.m.s. over kilometre separations caused by gravitational waves from astronomical sources. The sensitivity of currently operational and future gravitational-wave detectors is limited by quantum optical noise. Here, we demonstrate a 44% improvement in displacement sensitivity of a prototype gravitational-wave detector with suspended quasi-free mirrors at frequencies where the sensitivity is shot-noise-limited, by injecting a squeezed state of light. This demonstration is a critical step towards implementation of squeezing-enhancement in large-scale gravitational-wave detectors.

Additional Information

© 2008 Macmillan Publishers Limited. Received 5 November 2007; Accepted 26 February 2008; Published online 30 March 2008. We thank our colleagues at the LIGO Laboratory, especially the Quantum Measurement Group at MIT and the 40m Lab at Caltech, and also our colleagues at the Australian National University. This work was supported by National Science Foundation grants PHY-0107417 and PHY-0457264. Author contributions: K.G. played the leading role in carrying out the experiment reported here, which was part of his doctoral thesis. O.M., R.A., K.M., R.W., S.V. and A.J.W. maintained the best possible classical performance for the interferometer, whereas K.G., O.M., E.E.M., S.S. and N.M. were responsible for squeezed-state preparation, injection and squeeze-enhancement measurements. A.W. and N.M. are leaders of the Caltech 40m Lab and the MIT Quantum Measurement group, respectively.

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023