US-based next-generation gravitational wave detectors can currently be divided in two implementations: A# will feature 100 kg test masses and should operate at room temperature (RT), while Cosmic Explorer (CE) should feature even 320 kg test masses, and laser power reaching 1.5 MW in the arms, with its first incarnation operating at RT. In the former, sensitivity limits in the most sensitive...
Alex Amato, on behalf of the GWFP group of Maastricht University.
While current gravitational-wave detectors allow for successful detections, there is a need to increase their sensitivity by trying to enlarge their frequency band to observe additional types of gravitational waves sources. Future cryogenic detectors such as the Einstein Telescope aim for this improvement. Improved operating...
Reducing coating thermal noise (CTN) in mirrors for gravitational wave (GW) interferometers is pivotal to improve sensitivity in the mid-frequency range. Mirror coatings are Bragg’s mirrors alternating between high and low refractive index layers.
Commonly, amorphous coatings are heat-treated post-deposition in order to both reduce their internal strains and improve their optical quality....
Enhancing the performance of GWD mirrors is a complex endeavor which entails several key steps, including the selection of a suitable mirror design, the choice of the most appropriate chemical composition of coatings and the protocol for post-deposition treatments – i.e., thermal annealing.
During more than two decades of continuous research and development [1,2], a lot of effort has been...
We present a first-principles study of the vibrational spectra, i.e. vibrational density of states ($v$-DOS), infrared (IR), and Raman spectra, in amorphous tantala ($a$-Ta$_2$O$_5$). Model structures of upto three-hundreds atoms have been generated by means of classical and ab-initio molecular dynamics. An unprecedented series of ab-initio test calculations of the $v$-DOS and the IR...
Amorphous silica coatings play a crucial role as mirror components in gravitational wave detectors, such as those used in the Virgo experiment at the European Observatory in Cascina (PI, Italy). Exceptionally high sensitivity is required for the detection of gravitational waves and thermal noise from mirror coatings is one of the main limiting factors in the spectral region where the detector...
Low-temperature physical vapor deposition is studied by means of molecular dynamics (MD) simulations using the reactive force field (ReaxFF) potential. In contrast with prior MD studies of this process, which employed non-reactive, rigid ion force fields, our approach allows for accurate modeling of the reactive incorporation of impinging particles, generated by the vaporization process, into...
Knowledge of the frequency-dependence of the acoustic attenuation in structural glasses is necessary to understand their universal low temperature thermal properties. However, very little experimental information is currently available on the vibrational properties of glasses in the frequency range between 100 GHz and 1 THz, corresponding to the temperature range relevant for these thermal...
Coatings of materials with low optical and mechanical losses find prominent application in present terrestrial interferometric gravitational-wave detectors. The mirrors of the interferometers currently consist of fused silica substrates coated with stacks of alternating layers of amorphous silica and titania-tantala mixing. Research and development of novel materials is very active, since a...
To further reduce the mirror coating thermal noise for the Einstein Telescope (ET) and other third-generation gravitational wave detectors, a substantial improvement in the coating technology and material is necessary. Employing crystalline coatings is one of the new promising directions of the scientific endeavor to replace SiO2 and Ti:Ta2O5 for...
We are developing and tuning a facility to support the end-to-end discharge test campaign, part of the LISA Gravitational Reference System(GRS) test campaign, which probes directly the photo-current produced by UV illumination of the Test Mass and Electrode Housing via an electrometer. LISA Test Masses will be subject to collisions from charged space particles with energies >100 MeV, which...
LISA will integrate in the gravitational reference system (GRS) an ultra‐violet (UV) illumination device that will avoid excessive charge build-up on the test masses (TM) by producing appropriate photoelectron currents.
The properties of the gold-coated surfaces of the TM, and of the electrode housing that surrounds it, play a crucial role in determining the performance of this discharge...
Monocrystalline silicon fibers are a promising candidate to be used in gravitational-wave detectors for suspension of silicon test masses. High thermal conductivity and mechanical quality factor Q, very low thermal expansion coefficient, large strength-to-weight factor and compatibility with test masses enable stable support of heavy silicon mirrors and effective extraction of laser beam heat...
With this talk, I will first illustrate the implementation of our machine-learning (ML) enhanced quantum state tomography (QST) for continuous variables, through the experimentally measured data generated from squeezed vacuum states, as an example of quantum machine learning. Our recent progress in applying such a ML-QST as a crucial diagnostic toolbox for applications with squeezed states,...
Since the third observation run, Quantum Noise Reduction (QNR) techniques have become fundamental for Gravitational Wave Detectors (GWDs). Various alternatives to broadband QNR are currently being investigated. Specifically, we are exploring the measurement of a GWD signal in the reference frame of an auxiliary quantum system that mimics the dynamics of a free mass and exhibits the same...
We explore the idea of quantum noise reduction in contemporary gravitational wave detectors (GWDs), outlined in [1,2]. In that theoretical proposal, the measurement on the GWD should be performed in a reference frame of the auxiliary quantum system, which has the same response to the quantum noise. If the reference quantum system acts as a harmonic oscillator with an effective negative mass...
The implementation of Fabry-Perot cavities in gravitational-wave detectors has been pivotal to improving their sensitivity, allowing the observation of an increasing number of cosmological events with higher signal-to-noise ratio. Notably, Fabry-Perot cavities play a key role in the frequency-dependent squeezing technique, which provides a reduction of quantum noise over the whole observation...
Quantum noise fundamentally limits the performance of ground-based interferometric gravitational wave detectors (GWDs).
The quantum nature of the light and its interaction with the interferometer defines the so-called interferometric standard quantum limit (SQL).
To further upgrade the GWDs sensitivities, as in the planned A+, VIRGO_nEXT, Einstein Telescope, and Cosmic Explorer, more...
Optical losses introduce noise, impair noise reduction techniques, and degrade signal gain in gravitational wave detectors. The squeezed vacuum state of light is a well-established method for quantum noise reduction. An optical cavity, often called a filter cavity, is essential to impose a frequency-dependent phase rotation on the squeezed vacuum. In the Virgo gravitational wave detector, the...
Phase noise consists into the oscillation of the squeezing angle and it is one of the mechanisms that can degrade the level of squeezing injected in gravitational wave detectors used to reduce quantum noise. This jitter can be due to several reasons. In this talk, we want to show the analysis done to evaluate the contribution given to this noise by the interferometer contrast defect and...
Black hole-neutron star (NSBH) coalescence events are regarded as highly significant phenomena within the current multimessenger framework of gravitational waves,
and they are poised to assume an increasingly prominent role in the foreseeable future. To date, only a handful of such events have been observed,
with GW200105 and GW200115 being the most noteworthy among them. However, with the...
In this contribution I present the capabilities of ground-based third generation detectors to constrain the presence of non-tensor polarization modes in gravitational wave (GW) signals. These capabilities are assessed with mathematically simple figures of merit that discriminate between different theories of gravity. Different theories predict different polarization modes for GW emission by a...
Gravitational wave approximants are extremely useful tools in gravitational wave astronomy. By skipping the full evolution of numerical relativity waveforms, their usage allows for dense coverage of the parameter space of binary black hole (BBH) mergers for purposes of parameter inference, or, more generally, match filtering tasks. However, these benefits come at a slight cost to accuracy when...
The advent of third generation GW detectors, including the Einstein Telescope, will enable the detection of GW signals not only from the inspiral phase, but also from the post-merger phase of two coalescing neutron stars. The post-merger signal is potentially extremely rich and can shed light on the fate of the remnant, as well as on properties of matter at the highest densities reached in...
Stray light is an issue in any optical interference measurement, particularly in interferometric gravitational wave detectors, where stringent limits are placed on the noise floor: the control and mitigation of stray light are critical. After general considerations about stray light, this presentation will address the development underway of an instrumentation for stray light measurement at...
As straylight is an important limitation for the sensitivity of gravitational wave detectors, we investigate new laser operation concepts and interferometer topologies for a more straylight-resilient detector configuration.
Our main focus is the use of tunable coherence realized by phase modulation following a pseudo-random-sequence on the interferometer laser. This breaks the coherence of...
The performance of a giant interferometric detector such as Virgo or LISA can be affected by the presence of coherent stray light. In particular, it can be generated by the scattering of laser beams at the various interfaces of the instrument. It is therefore particularly important to be able to characterize in amplitude and phase the fraction of this scattered light that interacts coherently...
The AEI 10m Prototype will operate a Fabry Perot Michelson interferometer with 10m long arm cavities limited by the standard quantum limit (SQL). It will be a test-bed for testing and developing technologies improving the sensitivity of gravitational wave detectors beyond SQL. In order to achieve SQL-limited sensitivity, we need to suppress all other classical and technical noise sources....
High cleanliness levels are a prerequisite for GW detectors with laser interferometers: this can guarantee that light scattering is minimized and under control as being limited by the quality of the optical components. Assessing the cleanliness requirements involves sizing the stray light noise added by dust particles deposited on the optical components or floating and crossing the light...
In this presentation, I will review the stray-light mitigation activities for the KAGRA interferometer since its construction began. The stray light, including ghost beams and scattered light generated within the interferometer, is unwanted, as it somehow recombines with the main beam path and eventually becomes noise, which practically limits the interferometer sensitivity. To suppress the...
Gravitational waves offer us a unique tool to study binary neutron star (BNS) systems and the supranuclear-dense matter that comprises these objects. The gravitational-wave signal emitted during a BNS coalescence depends on the neutron stars’ properties, including their masses, spins, and tidal deformabilities. The increased sensitivity of future-generation detectors, such as the Einstein...
The detection of the gravitational wave (GW) signal GW170817 and the electromagnetic (EM) signal AT2017gfo confirmed the association between binary neutron star (BNS) mergers and kilonovae (KNe) and showed the potential of joint detection to unveil the nature of neutron stars and the nucleosynthesis of heavy elements in the Universe. The next-generation GW interferometers, such as the Einstein...
The fourth observing run of the LIGO-Virgo-KAGRA network of gravitational-wave (GW) detectors is ongoing and will add a significant number of compact binary mergers to the catalogs of GW transient observations. This is expected to further advance our understanding of astrophysics, cosmology and fundamental physics. The current network of interferometers is expected to reach design sensitivity...
Crystalline materials are playing a major role in determining the design, thermal and structural behavior of suspensions for the test masses of future gravitational wave interferometers that will use cryogenic payloads. The talk will present the state of the art of the joint research between various laboratories, research centers and private companies regarding the development of cryogenic...
Almost all future plans for gravitational wave detectors foresee operation at increasingly higher power levels to reduce shot noise, making residual aberrations from thermal effects more critical, potentially becoming a limiting factor despite the effectiveness of current correction methods.
Since the beginning of the Virgo project, we made significant strides in mitigating...
The birefringence that can occur in the optics that will be used in the Einstein Telescope (ET) interferometer is an essential phenomenon to be considered to ensure the desired sensitivity for gravitational wave (GW) detection.
The birefringence of the optics directly depends on the substrate and coating materials and is mainly induced by stress in these materials (residual internal stress,...
In this talk, I will present the state of the art and the new perspectives in the theoretical and experimental study of analog models of quantum field theories in flat, curved, or time-dependent backgrounds using condensed matter and optical systems.
I will start with a brief presentation of the general concept of analog mode and a review of milestone theoretical and experimental works on...
One of the key elements for LISA to achieve the required sensitivity for gravitational wave detection is the nearly geodesic free-fall of the test masses, down to a sub-femto-g performance at milliHertz frequencies. LISA Pathfinder, which surpassed its requirements and achieved the LISA ones, represents an important benchmark in this context.
We will review the latest advances in the...
The design of Gravitational Reference Systems (GRS) heavily hinges on the technologies developed, such as the mechanisms in charge of securing a reference test mass (TM) during the mission launch and then releasing it into free fall.
Such mechanisms need to be tested to ensure they minimize friction, adhesion, and fretting at the contacting surfaces, since space environment provides critical...
The Gravitational Reference System proved exceptional acceleration noise performance during the LISA Pathfinder mission. Indeed, the LISA Pathfinder mission demonstrated a performance that was better than the LISA requirements at all frequencies.
Building on the success of the LISA Pathfinder, the LISA Gravitational Reference System is being upgraded to meet the unique demands of the LISA...
LISA will be the first gravitational waves observer in space, consisting of three spacecraft in a triangular formation trailing the Earth along its orbit. Within each spacecraft, two gravitational reference sensors (GRSs) enclose cubic test masses (TMs), which are free-falling during the science phase. Besides providing a safe environment for the TM, shielding it from non-gravitational forces,...
In this paper, we delineate the engineering hurdles and envisaged an infrastructure of a newly proposed hill-contained, vertically positioned Gravity Decelerator. This decelerator possesses several attributes, specifically: (a) a 2,300 meters-long vertical vacuum tube designed for decelerating a low-energy beam of heavy ions and protons, facilitated by gravity; (b) a 12 meter diameter, Dark...
