arXiv subjects

S. Danilishin

Publications and source records attributed to S. Danilishin.

8 recordsLinked to original sources

arXiv2022

ETpathfinder: a cryogenic testbed for interferometric gravitational-wave detectors

The third-generation of gravitational wave observatories, such as the Einstein Telescope (ET) and Cosmic Explorer (CE), aim for an improvement in sensitivity of at least a factor of ten over a wide frequency range compared to the current advanced detectors. In order to inform the design of the third-generation detectors and to develop and qualify their subsystems, dedicated test facilities are required. ETpathfinder prototype uses full interferometer configurations and aims to provide a high sensitivity facility in a similar environment as ET. Along with the interferometry at 1550 nm and silicon test masses, ETpathfinder will focus on cryogenic technologies, lasers and optics at 2090 nm and advanced quantum-noise reduction schemes. This paper analyses the underpinning noise contributions and combines them into full noise budgets of the two initially targeted configurations: 1) operating with 1550 nm laser light and at a temperature of 18 K and 2) operating at 2090 nm wavelength and a temperature of 123 K.

astro-ph.IM↗

arXiv2019

Testing of Generalized Uncertainty Principle With Macroscopic Mechanical Oscillators and Pendulums

Recent progress in observing and manipulating mechanical oscillators at quantum regime provides new opportunities of studying fundamental physics, for example, to search for low energy signatures of quantum gravity. For example, it was recently proposed that such devices can be used to test quantum gravity effects, by detecting the change in the [x,p] commutation relation that could result from quantum gravity corrections. We show that such a correction results in a dependence of a resonant frequency of a mechanical oscillator on its amplitude, which is known as amplitude-frequency effect. By implementing this new method we measure amplitude-frequency effect for 0.3 kg ultra high-Q sapphire split-bar mechanical resonator and for 10 mg quartz bulk acoustic wave resonator. Our experiments with sapphire resonator have established the upper limit on quantum gravity correction constant for $β_0<5 \times10^6$ which is a factor of 6 better than previously detected. The reasonable estimates of $β_0$ from experiments with quartz resonators yield an even more stringent limit of $4\times10^4$. The data sets of 1936 measurement of physical pendulum period by Atkinson results in significantly stronger limitations on $β_0 \ll 1$. Yet, due to the lack of proper pendulum frequency stability measurement in these experiments, the exact upper bound on $β_0$ can not be reliably established. Moreover, pendulum based systems only allow testing a specific form of the modified commutator that depends on the mean value of momentum. The electro-mechanical oscillators to the contrary enable testing of any form of generalized uncertainty principle directly due to much higher stability and a higher degree of control.

quant-ph↗

arXiv2017

Speedmeter scheme for gravitational-wave detectors based on EPR quantum entanglement

We propose a new implementation of a quantum speed meter QND measurement scheme. It employs two independent optical readouts of the interferometer test masses, featuring strongly different values of the bandwidths $γ_{1,2}$ and of the optical circulating power $I_{1,2}$, with the special relationship of $I_1/I_2=γ_1/γ_2$. The outputs of these two position meters have to be combined by an additional beamsplitter. In this scheme, signals at the common and the differential outputs of the interferometer setup are proportional to the position and the velocity of the test masses, respectively. The influence of the position meter-like back action force associated with the position signal can be cancelled using the EPR approach by measuring the amplitude quadrature of the beamsplitter common output correlated with this force. In the standard signal-recycled Michelson interferometer topology of the modern gravitational-wave detectors, two independent optical position meters can be implemented by two orthogonal polarisations of the probe light. Our analysis shows that the EPR speedmeter provides significantly improved sensitivity for all frequencies below $\sim 30\,{\rm Hz}$ compared to an equivalent signal recycled Michelson interferometer. We believe the EPR speedmeter scheme to be very attractive for future upgrades of gravitational wave detectors, because it requires only minor changes to be implemented in the interferometer hardware and allows to switch between the position meter and the speed meter modes within short time-scales and without any changes to the hardware.

gr-qc↗

arXiv2014

Observation of the Three-Mode Parametric Instability

Three-mode parametric interactions occur in triply-resonant optomechanical systems: photons from an optical pump mode are coherently scattered to a high-order mode by mechanical motion of the cavity mirrors, and these modes resonantly interact via radiation pressure force when certain conditions are met. Such effects are predicted to occur in long baseline advanced gravitational-wave detectors. They can pump energy into acoustic modes, leading to parametric instability, but they can also extract acoustic energy, leading to optomechanical cooling. We develop a large amplitude model of three-mode interactions that explains the ring-up amplitude saturation after instability occurs. We also demonstrate both radiation-pressure cooling and mechanical amplification in two different three-mode optomechanical systems, including the first observation of the three-mode parametric instability in a free-space Fabry-Perot cavity. The experimental data agrees well with the theoretical model. Contrary to expectations, parametric instability does not lead to loss of cavity lock, a fact which may make it easier to implement control techniques to overcome instability.

physics.optics↗

arXiv2012

Scientific Potential of Einstein Telescope

Einstein gravitational-wave Telescope (ET) is a design study funded by the European Commission to explore the technological challenges of and scientific benefits from building a third generation gravitational wave detector. The three-year study, which concluded earlier this year, has formulated the conceptual design of an observatory that can support the implementation of new technology for the next two to three decades. The goal of this talk is to introduce the audience to the overall aims and objectives of the project and to enumerate ET's potential to influence our understanding of fundamental physics, astrophysics and cosmology.

gr-qc↗

arXiv2012

Scientific Objectives of Einstein Telescope

The advanced interferometer network will herald a new era in observational astronomy. There is a very strong science case to go beyond the advanced detector network and build detectors that operate in a frequency range from 1 Hz-10 kHz, with sensitivity a factor ten better in amplitude. Such detectors will be able to probe a range of topics in nuclear physics, astronomy, cosmology and fundamental physics, providing insights into many unsolved problems in these areas.

gr-qc↗

arXiv2011

Laser interferometry with translucent and absorbing mechanical oscillators

The sensitivity of laser interferometers can be pushed into regimes that enable the direct observation of quantum behaviour of mechanical oscillators. In the past, membranes with subwavelength thickness (thin films) have been proposed as high-mechanical-quality, low-thermal-noise oscillators. Thin films from a homogenous material, however, generally show considerable light transmission accompanied by heating due to light absorption, which typically reduces the mechanical quality and limits quantum opto-mechanical experiments in particular at low temperatures. In this work, we experimentally analyze a Michelson-Sagnac interferometer including a translucent silicon nitride (SiN) membrane with subwavelength thickness. We find that such an interferometer provides an operational point being optimally suited for quantum opto-mechanical experiments with translucent oscillators. In case of a balanced beam splitter of the interferometer, the membrane can be placed at a node of the electro-magnetic field, which simultaneously provides lowest absorption and optimum laser noise rejection at the signal port. We compare the optical and mechanical model of our interferometer with experimental data and confirm that the SiN membrane can be coupled to a laser power of the order of one Watt at 1064 nm without significantly degrading the membrane's quality factor of the order 10^6, at room temperature.

physics.optics↗

arXiv2010

Sensitivity Studies for Third-Generation Gravitational Wave Observatories

Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions.

gr-qc↗