Gravitational-wave astronomy began in 2015 with the Nobel Prize-winning discovery of signals produced by two black holes. Over the past eight years, LIGO and Virgo have observed over 100 gravitational-wave sources, yielding a plethora of scientific insights ranging from general relativity to astrophysics and cosmology.
 
The next generation of gravitational-wave (GW) detectors, including the European Einstein Telescope (ET), is currently under study, aiming for a tenfold improvement in sensitivity compared to LIGO and Virgo. This advancement will enable the exploration of fundamental questions about gravitation, dark energy, nuclear matter properties, and the formation of neutron stars and black holes throughout cosmic history.
 
A key technology to enhance sensitivity is known as 'quantum squeezing,' aimed to reduce quantum noise. Quantum noise, caused by vacuum fluctuations entering the detector, can be mitigated by replacing the vacuum with a manipulated 'squeezed' vacuum. Squeezed states, produced by non-linear optics and quantum correlations, have already demonstrated remarkable sensitivity in Virgo and LIGO. Currently, a more sophisticated 'frequency-dependent squeezing' (FDS) is being employed to mitigate quantum noise across the entire detection bandwidth by reflecting squeezed states off a 300-meter optical cavity. 
 
The PhD project aims to explore new avenues in the squeezed state manipulation for next generation gravitational-wave.

The candidate will primarily focus on realizing an ANR (Agence Nationale de la Recherche) funded experiment in the Virgo optics laboratory at APC. They will also contribute to optimizing the quantum squeezing source currently installed in Virgo.