High-precision cavity spectroscopy using high-frequency squeezed light

Reconstructing Gaussian bipartite states with a single polarization-sensitive homodyne detector

We present a novel method to fully estimate Gaussian bipartite polarization states using only a single homodyne detector. Our approach is based on [Phys. Rev. Lett.102, 020502 (2009)10.1103/PhysRevLett.102.020502], but circumvents additional optics, and thereby losses, in the signal path. We provide an intuitive explanation of our scheme without needing to define auxiliary modes. With six independent measurements, we fully reconstruct the state's covariance matrix. We validate our method by comparing it to a conventional dual-homodyne measurement scheme.

Frequency-Dependent Squeezing from a Detuned Squeezer

Frequency-dependent squeezing is a promising technique to overcome the standard quantum limit in optomechanical force measurements, e.g., gravitational wave detectors. For the first time, we show that frequency-dependent squeezing can be produced by detuning an optical parametric oscillator from resonance. Its frequency-dependent Wigner function is reconstructed quantum tomographically and exhibits a rotation by 39°, along which the noise is reduced by up to 5.5 dB. Our setup is suitable for realizing effective negative-mass oscillators required for coherent quantum noise cancellation.

Squeezing in Gravitational Wave Detectors

Injecting optical squeezed states of light, a technique known as squeezing, is now a tool for gravitational wave detection. Its ability to reduce quantum noise is helping to reveal more gravitational wave transients, expanding the catalog of observations in the last observing run. This review introduces squeezing and its history in the context of gravitational-wave detectors. It overviews the benefits, limitations and methods of incorporating squeezing into advanced interferometers, emphasizing the most relevant details for astrophysics instrumentation.