OPTICAL CONFIGURATIONS WORKING GROUP : The first point A. Freise - Birmingham P. Hello LAL-Orsay Cascina

Set up of the WG Call for participation => a number of happy volunteers F. Bondu (optics) A.Di Virgilio (flat beams …) A. Heidman’s group (quantum noise …) A. Giazotto (all reflective interferometers and squeezing) V. Rudenko’s group E. Tournefier …

Mid-term work (I) AF+PH =>the most important is to study : - SR and related issues Quantum noise Locking schemes Lock Acquisition - Flat/mesa beams first : define a roadmap Not independant of other WGs (thermal noise) Other (interesting) topics like all-reflective itfs to be studied later

Mid-term work (II) AF+PH => compile a consistent data set For some likely and possible scenarios. This can be the basis for an iterative process with the related working groups, e.g. on thermal noise input optics, control, etc. This will also provide a basis for comparable simulation results. Provide concrete layout proposals

Need for extra modelling/simulation (I) SR configuration : Need to compare different locking and lock acquisition schemes using frequency domain and time domain simulations. 2 possibilities for time domain: evolve SIESTA (require some developpement) use E2E -> Discussion with A. Viceré … Main actors likely to be involved : M. Varvella (Orsay) and XXXX (Firenze) => To be decided before summer …

Need for extra modelling/simulation (II) Optical specifications for advances configurations need specialised optical sim code. -> DarkF (FFT code made user-friendly) can handle power recycled itf (carrier+sb) -> Discussion with JYV … Work to be done : implement SR implement flat beams config. Again man power needed … … ask for a post doc for Birmingham/Orsay/Nice ?

Quantum noise in interferometers Standard config. -> SR config Kimble et al. -> Buonanno & Chen Bars & Courty (LKB) : XXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXX

WG Organisation Regular telecons The first one : soon ! ( will circulate) Something Else ?

conclusions Reasonable mid-term road map : SR Flat beams Need for man power for effective work Longer term issues like all reflective itfs … Optimization of optical configuration depends on other interferometer parts …