A5081698341- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Mechanical and Optical Resonators
- Geophysics and Gravity Measurements
- Geophysics and Sensor Technology
- Astrophysical Phenomena and Observations
- Cold Atom Physics and Bose-Einstein Condensates
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Advanced Fiber Laser Technologies
- High-pressure geophysics and materials
- Atomic and Subatomic Physics Research
- Dark Matter and Cosmic Phenomena
- Magnetic confinement fusion research
- Solar and Space Plasma Dynamics
- Advanced MEMS and NEMS Technologies
- Seismic Waves and Analysis
- Radio Astronomy Observations and Technology
- Lubricants and Their Additives
- Advanced Thermodynamics and Statistical Mechanics
- Superconducting Materials and Applications
- Advanced Frequency and Time Standards
- Tribology and Wear Analysis
- Photonic and Optical Devices
- Force Microscopy Techniques and Applications
The University of Tokyo
2016-2025
Massachusetts Institute of Technology
2020-2024
Tokyo University of Science
2023-2024
Osaka Electro-Communication University
2024
California Institute of Technology
2023
Institute of Space and Astronautical Science
2021-2023
Japan Aerospace Exploration Agency
2021-2023
Honda (Japan)
2014-2018
Honda (United States)
2015
National Institute for Fusion Science
2002
Quantum noise imposes a fundamental limitation on the sensitivity of interferometric gravitational-wave detectors like LIGO, manifesting as shot and quantum radiation pressure noise. Here, we present first realization frequency-dependent squeezing in full-scale detectors, resulting reduction both noise, with broadband detector enhancement from tens hertz to several kilohertz. In LIGO Hanford detector, reduced amplitude by factor 1.6 (4.0 dB) near 1 kHz; Livingston was 1.9 (5.8 dB). These...
The first detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015 launched era gravitational-wave astronomy. quest for signals from objects that are fainter or farther away impels technological advances to realize ever more sensitive detectors. Since 2019, one advanced technique, injection squeezed states light, is being used improve shot-noise limit sensitivity Advanced LIGO detectors, at frequencies above ∼50 Hz. Below this frequency,...
Abstract KAGRA is a newly build gravitational wave observatory, laser interferometer with 3 km arm length, located in Kamioka, Gifu, Japan. In this paper, one of series articles featuring KAGRA, we discuss the science targets projects, considering not only baseline (current design) but also its future upgrade candidates (KAGRA+) for near to middle term ($\sim$5 years).
Gravity generated by large masses has been observed using a variety of probes from atomic interferometers to torsional balances. However, gravitational coupling between small never so far. Here, we demonstrate sensitive displacement sensing the Brownian motion an optically trapped 7 mg pendulum whose natural quality factor is increased 10^{8} through dissipation dilution. The sensitivity for integration time one second corresponds in millimeter-scale experiment probe and 100 source mass,...
Gravitational waves have only two polarization modes in general relativity. However, there are six possible of a generic metric theory gravity. Thus, tests gravitational-wave can be tools for pursuing the nature space-time structure. The observations gravitational with worldwide network interferometric detectors such as Advanced LIGO, Virgo, and KAGRA will make it to obtain information from detector signals. We study separability inspiral compact binary coalescences systematically. Unlike...
The detection of gravitational waves from compact binary mergers by LIGO has opened the era wave astronomy, revealing a previously hidden side cosmos.To maximize reach existing observatory facilities, we have designed new instrument able to detect at distances 5 times further away than possible with Advanced LIGO, or greater 100 event rate.Observations this will make dramatic steps toward understanding physics nearby universe, as well observing universe out cosmological black hole...
Precise measurements of the displacement of, and force acting on, a mechanical oscillator can be performed by coupling to an optical cavity. Brownian thermal forces represent fundamental limit measurement sensitivity which impedes ability use precise as tool enquiry, particularly in context macroscopic quantum tabletop gravitational experiments. A torsion pendulum with low resonant frequency limited very small forces---from its suspensions---at frequencies above resonance. Here, we report...
There exist six possible polarization modes of gravitational waves in a general metric theory gravity, while two tensor are allowed relativity. The properties and number depend on gravity theories. For transient signals, the detectors needs to be basically equal gravitational-wave for separation polarizations. However, single detector having great sensitivity at lower frequency could effectively regarded as virtual network including set along its trajectory due long signal from compact...
Quantum mechanics predicts superpositions of position states even for macroscopic objects. Recently, the use a quasifreely suspended mirror combined with laser was proposed to prepare such [H. M\"uller-Ebhardt et al., Phys. Rev. Lett. 100, 013601 (2008)]. One key milestones towards this goal is preparation mechanical oscillator mainly driven by measurement-induced backaction in quantum regime. Here we describe observation acting on 5-mg classical Furthermore, its component estimated be...
In this study, we investigated tribological properties of "tetrahedral" Si-containing hydrogenated DLC coating (TMS coating) during sliding against steel or cast-iron lubricated with engine-oil containing MoDTC and ZnDTP additives. TMS coatings derived from only tetramethylsilane were prepared using PACVD high-bias process. had the highly carbon sp3 bonded structure induced by Si (over 20 at.%) high hydrogen content (30 at.%). TOF-SIMS analysis showed that could form additive-derived...
Upgrades to improve the sensitivity of gravitational wave detectors enable more frequent detections and precise source parameter estimation. Unlike other advanced interferometric such as Advanced LIGO Virgo, KAGRA requires a different approach for upgrade since it is only detector which employs cryogenic cooling test masses. In this paper, we describe possible upgrades with technologies focusing on bands compare impacts detection compact binary coalescences. We show that either fivefold...
DECIGO is the future Japanese gravitational wave detector in outer space. We previously set default design parameters to provide a good target sensitivity detect primordial waves (GWs). However, updated upper limit of GWs by Planck observations motivated us for further optimization sensitivity. Previously, we had not considered optical diffraction loss due very long cavity length. In this paper, optimize various maximizing signal-to-noise ratio (SNR), quantum noise including effects loss....
We propose and experimentally demonstrate the generation of enhanced optical springs using Kerr effect. A nonlinear crystal is inserted into a Fabry-Perot cavity with movable mirror, chain second-order effects in phase-mismatched condition induces The spring constant by factor 1.6±0.1 over linear theory. To our knowledge, this first realization optomechanical coupling enhancement effect, which has been theoretically investigated to overcome performance limitations systems. tunable...
Cryogenic cooling of the test masses interferometric gravitational wave detectors is a promising way to reduce thermal noise. However, cryogenic limits incident power masses, which freedom shaping quantum also requires short and thick suspension fibers extract heat, could result in worsening Therefore, careful tuning multiple parameters necessary designing sensitivity detectors. Here, we propose use particle swarm optimization optimize these We apply it for KAGRA detector, show that binary...
The test mass suspensions of cryogenic gravitational-wave detectors such as the KAGRA project are tasked with extracting heat deposited on optics. Thus these have a non-uniform temperature, requiring calculation thermal noise in non-equilibrium conditions. While it is not possible to describe whole suspension system one local temperature anywhere still well defined. We therefore generalize application fluctuation-dissipation theorem mechanical systems, pioneered by Saulson and Levin,...
KAGRA is a 3-km cryogenic interferometric gravitational wave telescope located at an underground site in Japan. In order to achieve its target sensitivity, the relative positions of mirrors interferometer must be finely adjusted with attached actuators. We have developed model simulate length control loops realistic suspension responses and various noises for mirror actuation. Using our model, we designed actuation parameters sufficient force range acquire lock as well all degrees freedom...
The DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is designed to detect gravitational waves at frequencies between 0.1 and 10 Hz. In this frequency band, one of the most important science targets detection primordial waves. DECIGO plans use a space interferometer with optical cavities increase its sensitivity. For evaluating sensitivity, diffraction laser light has be adequately considered. There are two kinds loss: leakage loss outside mirror higher-order mode loss....
In LHD discharges, the NBI heated plasmas are terminated in two ways: (a) thermal decay (TD) after termination of and (b) radiative collapse (RC) during heating. The basic characteristics TD RC discharges compared. It is found that plasma mainly governed by heating power density. critical density c for similar to scaling laws obtained other helical devices, i.e. c∝(PB/V)0.5, where P, B V denote power, magnetic field volume, respectively. Moreover, measurements using multichannel bolometric...