Squeezed light for the interferometric detection of highfrequency gravitational waves
Abstract
The quantum noise of the light field is a fundamental noise source in interferometric gravitationalwave detectors. Injected squeezed light is capable of reducing the quantum noise contribution to the detector noise floor to values that surpass the socalled standard quantum limit (SQL). In particular, squeezed light is useful for the detection of gravitational waves at high frequencies where interferometers are typically shotnoise limited, although the SQL might not be beaten in this case. We theoretically analyse the quantum noise of the signalrecycled laser interferometric gravitationalwave detector GEO 600 with additional input and output optics, namely frequencydependent squeezing of the vacuum state of light entering the dark port and frequencydependent homodyne detection. We focus on the frequency range between 1 kHz and 10 kHz, where, although signal recycled, the detector is still shotnoise limited. It is found that the GEO 600 detector with present design parameters will benefit from frequencydependent squeezed light. Assuming a squeezing strength of 6 dB in quantum noise variance, the interferometer will become thermal noise limited up to 4 kHz without further reduction of bandwidth. At higher frequencies the linear noise spectral density of GEO 600 will still be dominated by shot noise and improved by a factor of 10^{6dB/20dB} ap 2 according to the squeezing strength assumed. The interferometer might reach a strain sensitivity of 6 × 10^{23} above 1 kHz (tunable) with a bandwidth of around 350 Hz. We propose a scheme to implement the desired frequencydependent squeezing by introducing an additional optical component into GEO 600's signalrecycling cavity.
 Publication:

Classical and Quantum Gravity
 Pub Date:
 March 2004
 DOI:
 10.1088/02649381/21/5/099
 arXiv:
 arXiv:grqc/0401119
 Bibcode:
 2004CQGra..21S1045S
 Keywords:

 General Relativity and Quantum Cosmology
 EPrint:
 Presentation at AMALDI Conference 2003 in Pisa