SMARTly Quantum light source for Einstein Telescope


Funded by: Ministero dell´Universita e della Ricerca  
Start date: 2023-12-14  End date: 2025-12-15
Total Budget: EUR 222.600,00  INO share of the total budget: EUR 122.958,00
Scientific manager:    and for INO is: Parisi Maria

Organization/Institution/Company main assignee: CNR – Istituto Nazionale di Ottica (INO)

other Organization/Institution/Company involved:
Università di Napoli “Federico II”

other INO’s people involved:

Mosca Simona

Abstract: The need to open new horizons in the field of gravitational physics, drives the quest for the overcoming of quantum limits and the scientific curiosity towards sustainability strategy.
By exploiting the quantum nature of light, it is possible to reduce optical noise beyond the “Quantum Limit Standard” SQL using non-classical light states (squeezed).
In particular, the generation of quantum states of light is crucial to improve the sensitivity of interferometric gravitational wave detectors. In fact, recently the LIGO and Virgo Gravitational-Wave Observatories (GWOs) in advanced configurations have implemented optical schemes for the injection of squeezed vacuum states. In systems currently in use the efficient generation of squeezed states is obtained by nonlinear crystals of the second order (χ 2 Crystals) through processes of “parametric down-conversion”. Processes of this type allow the generation of squeezed light but they require complex and bulky optical cavities, necessary both for the generation of second harmonic (SHG) of the laser pump, and for the optical parametric oscillation (OPO) process. Furthermore, this equipment exhibits poor transportability, significant use of metals (aluminum, steel, stainless) and electronic circuits.
This proposal, acknowledging the centrality of sustainability, aims to carry out efficient generation of squeezed vacuum states in a smart device, directly at the required frequency with second order non-linearity, exploiting nonlinear cascading processes.
In view of the upcoming third-generation GW detector, Einstein Telescope (ET), the development of a smart squeezer represents an alternative quantum light source which reinforces and increases the likelihood of success of the “Einstein Telescope Infrastructure Consortium” (IR0000004-ETIC). ET will be a large-scale underground and cryogenic interferometer, to achieve design sensitivity it requires high level squeezed light. In this context, the development of cutting-edge devices “opening up new interesting perspectives” could bring enormous technological advantages in this field.
Starting from a continuous wave (cw) source, SMART_Q_ET project will realize a squeezed vacuum state around the pump frequency, directly in a nearly monolithic SHG resonator fused silica based. The glass is fully recyclable and guarantees a low environmental footprint. The proposed module squeezer exhibits short and long-term stability by making use of an ultra-compact design (single rigid nonlinear cavity module) and exploiting the very low thermo-mechanical response of material.
The final goal of SMART_Q_ET project is to achieve a squeezed vacuum state by a single highly stable and smart device. The modular nature of the device makes it attractive for various applications, not limited to the gravitational interferometry but to all cutting edge sensors that need to go beyond the quantum limit.