Quantum Noise Reduction in Gravitational Wave detectors via quantum entanglement

by Francesco De Marco (Sapienza University of Rome & Istituto Nazionale di Fisica Nucleare, Sezione di Roma1), Sumin Lee (Kyung Hee University)

Friday 24 May 2024, 10:30 → 11:30 Europe/Rome

Aula Rasetti (Dipartimento di Fisica - Ed. G. Marconi)

Gravitational-wave interferometric detectors

Francesco De Marco

Although Gravitational-waves (GWs) were predicted by Einstein within the General Relativity, their first direct detection is dated in 2015. This milestone discovery unveiled a completely new field with crucial implications in astrophysics, cosmology and fundamental physics. Today, the worldwide network of GW ground-based detectors, sensitive to the audio frequency band (10 Hz - 10 kHz), is made up of two LIGO antennas in the USA, Virgo in Italy, and KAGRA in Japan. The fourth joint observing run, O4, is now ongoing, and currently the catalog of GW signals is counting more than 180 events that originated from the coalescence of binary systems of compact astrophysical objects. GW detectors are extremely sensitive Michelson interferometers with km-long-baseline Fabry-Perot arms. This talk will give an overview on the basic working principle of a GW interferometric detector, along with the main offenders to GW detection: seismic noise, thermal noise and quantum noise. A special focus will be set on the quantum noise, and on the current strategies to mitigate its impact on the sensitivity of a GW interferometer.

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Compact Frequency-Dependent Squeezing for Enhanced Gravitational Wave Detection: The EPR Experiment and its Mode Matching Telescope

Sumin Lee

Squeezed light injection has proven to be a powerful technique for improving the sensitivity of gravitational wave (GW) detectors by reducing quantum noise. Frequency-dependent squeezing (FDS) further enhances detector performance by addressing the limitation caused by radiation pressure noise in the low-frequency region. The fourth observing run (O4) of GW detectors successfully implemented FDS using 300m-long Filter Cavities (FCs), but future detectors will require kilometer-long FCs, presenting significant infrastructure challenges. In order to address this issue, we are developing a table-top optical prototype that employs a more compact approach known as Einstein Podolsky Rosen (EPR) squeezing. This presentation will begin by introducing the EPR squeezing experiment, highlighting the advancements made in developing this compact FDS solution and discussing the challenges that lie ahead. Then, we will focus on the specific contribution of the presenter – the alignment and operation of the reflective Mode Matching Telescope (MMT). The MMT, designed, produced, and tested in Korea, plays a crucial role in the EPR squeezing setup. We will detail the optical design and alignment procedure of the MMT and present the results obtained so far.

Link zoom: https://uniroma1.zoom.us/j/85078619957?pwd=R3VkcDNCZXB3dW5uaE5NamxvbDd5dz09