Low-frequency squeezed light

The squeezed light experiment

The Squeezed Light Experiment at the Centre for Gravitational Physics

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 [1], we have developed a squeezed light source that can produce and control squeezed light on timescales commensurate with GW detector science runs [2], 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.

[1] K. McKenzie et al, Phys. Rev. Lett. 93, 161105 (2004) (paper)
[2] S. S. Y. Chua et al, Optics Letters 36, 4680-4682 (2011) (paper)
[3] M. S. Stefszky et al, Class. Quantum Grav. 29 145015 (2012) (paper)

Locked squeezed spectrum graph

Locked squeezed spectrum (Red trace) showing at least 10dB of noise reduction below Quantum Noise (Blue trace) across the audio gravitational wave detection band (10Hz – 10kHz), and 11.6dB noise reduction above 200Hz. Magenta trace is antisqueezed spectrum, and Black trace is electronics noise.

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 [4].

[4] A. R. Wade et al, Optics Letters 38 2265 (2013) (paper)

ANU squeezing graph with scattered light path modulation

Scatter was intentionally increased in the ANU Squeezing Experiment by removing select beam dumps. With applied modulation, contributions to the noise floor were reduced by up to 20 dB at the peak of the scatter noise roll up.

Contact

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McClelland, David profile
Professor
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