arXiv subjects

Margherita Turconi

Publications and source records attributed to Margherita Turconi.

5 recordsLinked to original sources

arXiv2026

Gravitational wave detectors from an experimental perspective

This chapter introduces the fundamental principles of gravitational wave detectors in a simple and comprehensive manner. Because these instruments aim for extremely high sensitivity, it is essential to understand their various noise sources, how such noise couples to the detector output, and the strategies used to mitigate them. These noises contributions are computed in the frame of the Virgo detector and a sensitivity curve is calculated. Although a simplified layout of a gravitational wave detector is considered, it takes into account the most dominant effects and yields in a sensitivity estimate close to the what is observed in real detectors.

physics.optics↗

arXiv2022

High speed, high power 2D beam steering for mitigation of optomechanical parametric instability in gravitational wave detectors

In this paper we propose a novel strategy to control optomechanical parametric instability (PI) in gravitational wave (GW) detectors, based on radiation pressure. The fast deflection of a high power beam is the key element of our approach. We built a 2D deflection system based on a pair of acousto-optic modulators (AOMs) that combines high rapidity and large scan range. As fast frequency switching configurable AOM driver we used an Universal Software Radio Peripheral (USRP) combined with a high performance personal computer (PC). In this way we demonstrate a 2D beam steering system with flat efficiency over the whole scan range and with a transition time of 50 ns between two arbitrary consecutive deflection positions for a beam power of 3.6 W.

gr-qc↗

arXiv2021

Probing electronic decoherence with high-resolution attosecond photoelectron interferometry

Quantum coherence plays a fundamental role in the study and control of ultrafast dynamics in matter. In the case of photoionization, entanglement of the photoelectron with the ion is a well known source of decoherence when only one of the particles is measured. Here we investigate decoherence due to entanglement of the radial and angular degrees of freedom of the photoelectron. We study two-photon ionization via the 2s2p autoionizing state in He using high spectral resolution photoelectron interferometry. Combining experiment and theory, we show that the strong dipole coupling of the 2s2p and 2p$^2$ states results in the entanglement of the angular and radial degrees of freedom. This translates, in angle integrated measurements, into a dynamic loss of coherence during autoionization.

physics.atom-ph↗

arXiv2019

Mitigation of Parametric Instability

A key action for enhancing the sensitivity of gravitational wave (GW) detectors based on laser interferometry is to increase the laser power. However, in such a high-power regime, a nonlinear optomechanical phenomenon called parametric instability (PI) leads to the amplification of the mirrors vibrational modes preventing the detector functioning. Thus this phenomenon limits the detectors maximum power and so its performances. Our group has started an experimental research program aiming at realizing a exible and active mitigation system, based on the radiation pressure applied by an auxiliary laser. A summary on the PI mitigation techniques will be presented, we will explain the working principle of the system that we are implementing and report about the first experimental results.

astro-ph.IM↗

arXiv2019

Generation of very high-order high purity Gaussian modes via spatial light modulation

We experimentally demonstrate the conversion of a fundamental $\text{TEM}_{00}$ laser mode at 1064\,nm to higher order Hermite-Gaussian modes (HG) of arbitrary order via a commercially available liquid crystal Spatial Light Modulator (SLM). We particularly studied the $\text{HG}_{5,5}/\text{HG}_{10,10}/\text{HG}_{15,15}$ modes. A two-mirror plano-spherical cavity filters the higher-order modes spatially. We analyze the cleaned modes via a three-mirror diagnosis cavity and measure a mode purity of 96/93/78\% and a conversion efficiency of 6.6\%/3.7\%/1.7\% respectively. The generated high-purity Hermite-Gaussian modes can be employed for the mitigation of mirror thermal noise in optical cavities for both optical clocks and gravitational wave (GW) detectors. HG modes are then converted into high order LG modes which can be of particular interest in cold atom physics.

gr-qc↗