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Intitulé du sujet: Reducing quantum noise in the gravitational-wave detectors Virgo and its upgrades

Sujet

Codirection:

Nombre de mois: 36 mois

Ecole Doctorale: ED 560 - Sciences de la Terre et de l'environnement et Physique de l'Univers

Unité de recherche et équipe:

The thesis will be performed in the Virgo group of the APC laboratory.

The AstroParticle and Cosmology Laboratory (APC) is a Joint Research Unit (UMR) created in 2005. The APC brings together 80 researchers and teacher-researchers, as well as 75 engineers, technicians and administrative staff. Including non-permanent staff (doctoral and post-doctoral students, contract engineers and technicians, apprentices and foreign visitors), the APC has a total staff of around 220. The APC is under the supervision of Université Paris Cité (UPCité) and CNRS, represented by three of its institutes: IN2P3 (the main institute), INSU and INP. The CEA (DSM/IRFU), the Observatoire de Paris and the CNES also supervise the laboratory.

The Virgo group of the APC, created in 2008, is composed of about 15 persons and covers various activities and responsibilities: development and construction of the detector and its upgrades, commissioning of Virgo, R&D in optics, for the development of new techniques for detector noise reduction, analysis and scientific interpretation of data.

The thesis will be carried out in the experimental part of the group consisting of 7 people, including a DR CNRS, a MCF UPCité, 2 PhD students, 2 postdocs, an IR

 

 

Coordonnées de l’équipe:

Laboratoire Astroparticule et Cosmologie

Université Paris Cité 

Bâtiment Condorcet 

10 Rue A.Domon et L.Duquet, 

75013 Paris, France 

Secteur: Sciences Physiques et Ingénierie / Physical sciences and Engineering

Langue attendue: Anglais

Niveau de langue attendu: B1

Description

Description du sujet:

Since the first detection of gravitational waves in 2015 and the multi-messenger observation of a binary neutron star merger in 2017, gravitational-wave astronomy has advanced rapidly, producing a wealth of scientific results in astrophysics, cosmology, and fundamental physics. The international gravitational-wave network LIGO-Virgo-KAGRA has already observed more than two hundred gravitational-wave sources, with plans underway to upgrade current detectors and expand their astrophysical reach. 

In this context, Virgo-LIGO-KAGRA will be taking data in the near future, with increasing sensitivity, through a programme of upgrades under study. Quantum noise is the noise that limits the sensitivity of these instruments in the broader frequency band and originates from the vacuum fluctuations entering the detector from the antisymmetric port, the one where the interference between the interferometer's laser beams occurs. One of the techniques, used since 2019, to reduce the noise is to inject squeezed vacuum states, with reduced correlations, produced by quantum optics techniques. The Virgo Group of the APC has a great deal of experience in this field, with a dozen publications in peer-to-peer journals and considerable international visibility. The obtention in 2023 of the ANR quantum-FRESCO allowed to start building a new squeezing source in the APC optical laboratory to be used in an experiment to demonstrate a non-trivial rotation of the squeezing ellipse, as well as new techniques to reduce optical losses in new generation squeezers, to be used for Virgo and future generation detectors, as Einstein Telescope. 

The thesis aims to explore squeezing optimisation techniques for Virgo and its upgrade in the 2030-2040 timeframe, called Virgo_nEXT. Namely: reduction of optical losses to 10 dB of squeezing, optimisation of the controls of the so-called quantum ‘filter cavity’, and optimisation of the mode-matching between the interfeometer beam and the squeezing beam.

The work will be performed in the optics laboratory of the APC and in the Virgo site, near Pisa. Missions to the LIGO and KAGRA interferometers are also possible. 

The link of the Virgo experimental group at APC is: https://quantum-fresco.in2p3.fr/intro.html

Compétences requises:

They are requested:

  • General skills in experimental physics
  • Skills in optics, optical interferometry
  • Basic skills in lasers
  • Linear signal analysis
  • Feedback Control theory  

Some basic knowledge of gravitational astronomy is appreciated. 

Références bibliographiques:

The publications of the Virgo experimental group are summarized at the link: https://quantum-fresco.in2p3.fr/Publications.html