Low-frequency squeezed light
Low frequency squeezed light generation
Low frequency squeezed light (or low frequency ‘squeezing’) at GW signal frequencies (10Hz-10kHz) can be used to reduce quantum noise in GW detectors.
From our group’s first demonstration of squeezing measured within the audio gravitational wave detection band using a degenerate Optical Parametric Oscillator , we have developed a squeezed light source that can produce and control squeezed light on timescales commensurate with GW detector science runs , and recently demonstrated at least 10dB of Quantum Noise reduction across the audio gravitational wave detection band [shown below – reference 3]
This work is done in collaboration with the ANU Quantum Optics group, the Quantum Measurement Group at MIT, USA and Albert Einstein Institute in Germany.
 K. McKenzie et al, Phys. Rev. Lett. 93, 161105 (2004) (paper)
 S. S. Y. Chua et al, Optics Letters 36, 4680-4682 (2011) (paper)
 M. S. Stefszky et al, Class. Quantum Grav. 29 145015 (2012) (paper)
Path length modulation technique for scatter-noise immunity in squeezing measurements
Scattered light is a significant limiting factor in the measurement and application of low frequency squeezed light sources. We present a path-length modulation technique that offers scattering immunity for the measurement of squeezed states without the need for additional isolating optics. This offers significant advantages for avoiding degradation of squeezing due to optical losses.
With calibrated modulation, contributions to the noise floor of the homodyne’s power spectral density (PSD) were reduced by up to 20 dB at the peak of the scatter noise roll up. This work is published in .
 A. R. Wade et al, Optics Letters 38 2265 (2013) (paper)