179 research outputs found

    Absorption and thermal issues

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    P. Willems, D. Ottaway and P. Beyersdorfhttp://www.cambridge.org/aus/catalogue/catalogue.asp?isbn=978110700338

    Observation of a kilogram-scale oscillator near its quantum ground state

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    We introduce a novel cooling technique capable of approaching the quantum ground state of a kilogram-scale system—an interferometric gravitational wave detector. The detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) operate within a factor of 10 of the standard quantum limit (SQL), providing a displacement sensitivity of 10<sup>−18</sup> m in a 100 Hz band centered on 150 Hz. With a new feedback strategy, we dynamically shift the resonant frequency of a 2.7 kg pendulum mode to lie within this optimal band, where its effective temperature falls as low as 1.4 μK, and its occupation number reaches about 200 quanta. This work shows how the exquisite sensitivity necessary to detect gravitational waves can be made available to probe the validity of quantum mechanics on an enormous mass scale

    Erratum: All-sky search for gravitational-wave bursts in the first joint LIGO-GEO-Virgo run (Physical Review D - Particles, Fields, Gravitation and Cosmology (2010) 81 (102001))

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    This paper was published online on 5 May 2010 with an omission in the Collaboration author list. S. Dwyer has been added as of 12 April 2012. The Collaboration author list is incorrect in the printed version of the journal

    Erratum: Search for gravitational waves from compact binary coalescence in LIGO and Virgo data from S5 and VSR1 (Physical Review D - Particles, Fields, Gravitation and Cosmology)

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    This paper was published online on 5 November 2010 with an omission in the Collaboration author list. S. Dwyer has been added as of 12 April 2012. The Collaboration author list is incorrect in the printed version of the journal

    Publisher's Note: Search for gravitational waves from binary black hole inspiral, merger, and ringdown

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    This paper was published online on 6 June 2011 with an omission in the Collaboration author list. S. Dwyer has been added as of 12 April 2012. The Collaboration author list is incorrect in the printed version of the journal

    Enhanced sensitivity of the LIGO gravitational wave detector by using squeezed states of light

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    LIGO Scientific Collaboration members: J. Munch, D. J. Ottaway, P. J. Veitch for University of Adelaide.Nearly a century after Einstein first predicted the existence of gravitational waves, a global network of Earth-based gravitational wave observatories¹,²,³,⁴ is seeking to directly detect this faint radiation using precision laser interferometry. Photon shot noise, due to the quantum nature of light, imposes a fundamental limit on the attometre-level sensitivity of the kilometre-scale Michelson interferometers deployed for this task. Here, we inject squeezed states to improve the performance of one of the detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) beyond the quantum noise limit, most notably in the frequency region down to 150 Hz, critically important for several astrophysical sources, with no deterioration of performance observed at any frequency. With the injection of squeezed states, this LIGO detector demonstrated the best broadband sensitivity to gravitational waves ever achieved, with important implications for observing the gravitational-wave Universe with unprecedented sensitivity.The LIGO Scientific Collaboratio

    Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts

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    <p>Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations.</p> <p>Methods. During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline’s ability to reconstruct source positions correctly.</p> <p>Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with ~50% or better probability with a few pointings of wide-field telescopes.</p&gt

    First LIGO search for gravitational wave bursts from cosmic (super)strings

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    We report on a matched-filter search for gravitational wave bursts from cosmic string cusps using LIGO data from the fourth science run (S4) which took place in February and March 2005. No gravitational waves were detected in 14.9 days of data from times when all three LIGO detectors were operating. We interpret the result in terms of a frequentist upper limit on the rate of gravitational wave bursts and use the limits on the rate to constrain the parameter space (string tension, reconnection probability, and loop sizes) of cosmic string models. Many grand unified theory-scale models (with string tension Gμ/c[superscript 2]≈10[superscript -6]) can be ruled out at 90% confidence for reconnection probabilities p≤10[superscript -3] if loop sizes are set by gravitational back reaction.Research CorporationAlfred P. Sloan FoundationDavid and Lucile Packard FoundationLeverhulme TrustAlexander von Humboldt FoundationJohn Simon Guggenheim FoundationNational Aeronautics and Space AdministrationSpanish Ministerio de Educacion y CienciaDepartment of Science and Technology of IndiaCouncil of Scientific and Industrial Research of IndiaNatural Sciences and Engineering Research Council of CanadaAustralian Research CouncilState of Niedersachsen/GermanyMax-Planck-SocietyParticle Physics and Astronomy Research Council of the United KingdomUnited States National Science Foundatio

    A gravitational wave observatory operating beyond the quantum shot-noise limit

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    Around the globe several observatories are seeking the first direct detection of gravitational waves (GWs). These waves are predicted by Einstein’s general theory of relativity and are generated, for example, by black-hole binary systems. Present GW detectors are Michelson-type kilometre-scale laser interferometers measuring the distance changes between mirrors suspended in vacuum. The sensitivity of these detectors at frequencies above several hundred hertz is limited by the vacuum (zero-point) fluctuations of the electromagnetic field. A quantum technology—the injection of squeezed light—offers a solution to this problem. Here we demonstrate the squeezed-light enhancement of GEO600, which will be the GWobservatory operated by the LIGO Scientific Collaboration in its search for GWs for the next 3–4 years. GEO600 now operates with its best ever sensitivity, which proves the usefulness of quantum entanglement and the qualification of squeezed light as a key technology for future GW astronomy.J. Abadie... M.R. Ganija... D.J. Hosken... J. Munch... D.J. Ottaway... P.J. Veitch... et al. J. Abadie... M. R. Ganija...D. J. Hosken... J. Munch... D. J. Ottaway... P. J. Veitch... et al., (LIGO Scientific Collaboration
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