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

Journal name:
Nature Photonics
Volume:
7,
Pages:
613–619
Year published:
DOI:
doi:10.1038/nphoton.2013.177
Received
Accepted
Published online

Abstract

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.

At a glance

Figures

  1. Simplified layout of the H1 interferometer with squeezed vacuum injection.
    Figure 1: Simplified layout of the H1 interferometer with squeezed vacuum injection.

    The interferometer layout is described in the text, together with the main squeezer components (shown in the grey box). The green box shows a simplified representation of coherent states and squeezed states in the in-phase and quadrature-phase coordinates.

  2. Strain sensitivity of the H1 detector measured with and without squeezing injection.
    Figure 2: Strain sensitivity of the H1 detector measured with and without squeezing injection.

    The improvement is up to 2.15 dB in the shot-noise-limited frequency band. Several effects cause the sharp lines visible in the spectra: mechanical resonances in the mirror suspensions, resonances of the internal mirror modes, power line harmonics and so on. As the broadband floor of the sensitivity is most relevant for gravitational-wave detection, these lines are typically not too harmful. The inset magnifies the frequency region between 150 and 300 Hz, showing that the squeezing enhancement persists down to 150 Hz.

  3. Comparison of possible sensitivity curves for Advanced LIGO.
    Figure 3: Comparison of possible sensitivity curves for Advanced LIGO.

    Projection for a squeezing-enhanced Advanced LIGO interferometer (continuous lines), using a design similar to the one described in this Letter, is compared to the Advanced LIGO sensitivity tuned for high-frequency performance (dashed lines). The total noise, in both cases, has been computed by considering all the main noise sources, but only thermal noise and quantum noise are shown, as they are the only relevant noise sources above 100 Hz. The total losses for the squeezed beam were assumed to be 10%, starting with 9 dB of squeezing delivered by the OPO and 35 mrad of phase noise. With the same parameters, but assuming the injection of optimal frequency-dependent squeezing, quantum noise can be reduced at all frequencies, as shown by the dash-dotted red line.

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  1. LIGO – California Institute of Technology, Pasadena, California 91125, USA

    • J. Aasi,
    • J. Abadie,
    • B. P. Abbott,
    • R. Abbott,
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  2. SUPA, University of Glasgow, Glasgow G12 8QQ, UK

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  4. Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, D-30167 Hannover, Germany

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  5. University of Wisconsin–Milwaukee, Milwaukee, Wisconsin 53201, USA

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  6. Stanford University, Stanford, California 94305, USA

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  7. LIGO – Hanford Observatory, Richland, Washington 99352, USA

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  8. University of Florida, Gainesville, Florida 32611, USA

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  9. Louisiana State University, Baton Rouge, Louisiana 70803, USA

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  10. University of Birmingham, Birmingham B15 2TT, UK

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  11. Leibniz Universität Hannover, D-30167 Hannover, Germany

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  12. Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, D-14476 Golm, Germany

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  13. Montana State University, Bozeman, Montana 59717, USA

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  14. Carleton College, Northfield, Minnesota 55057, USA

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  15. LIGO – Massachusetts Institute of Technology, Cambridge, Massachussetts 02139, USA

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  16. University of Western Australia, Crawley, Western Australia 6009, Australia

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  17. Columbia University, New York, New York 10027, USA

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  18. The University of Texas at Brownsville, Brownsville, Texas 78520, USA

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  19. San Jose State University, San Jose, California 95192, USA

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  20. Moscow State University, Moscow 119992, Russia

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  21. The Pennsylvania State University, University Park, Pennsylvania 16802, USA

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  22. Washington State University, Pullman, Washington 99164, USA

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  23. Caltech–CaRT, Pasadena, California 91125, USA

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  24. University of Oregon, Eugene, Oregon 97403, USA

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  25. Syracuse University, Syracuse, New York 13244, USA

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    • D. B. Kelley,
    • P. Kumar,
    • J. Lough,
    • S. R. P. Mohapatra,
    • A. Nitz,
    • A. Perreca,
    • P. R. Saulson &
    • M. West
  26. Rutherford Appleton Laboratory, HSIC, Chilton, Didcot, Oxon OX11 0QX, UK

    • R. J. S. Greenhalgh &
    • J. O'Dell
  27. University of Maryland, College Park, Maryland 20742, USA

    • A. Buonanno,
    • C. D. Capano,
    • Y. Pan,
    • P. Shawhan &
    • C. C. Yancey
  28. University of Massachusetts – Amherst, Amherst, Massachusetts 01003, USA

    • L. Cadonati,
    • J. A. Clark,
    • D. Hoak,
    • A. L. Lombardi &
    • J. McIver
  29. The University of Mississippi, University, Mississippi 38677, USA

    • C. Arceneaux,
    • M. Cavaglià &
    • A. Dietz
  30. NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771, USA

    • L. Blackburn,
    • J. B. Camp,
    • N. Gehrels,
    • P. B. Graff &
    • J. B. Kanner
  31. Tsinghua University, Beijing 100084, China

    • J. Cao,
    • Z. Du,
    • Y. Liu,
    • Y. Wan &
    • X. Wang
  32. University of Michigan, Ann Arbor, Michigan 48109, USA

    • S. Caride,
    • R. Gustafson,
    • G. D. Meadors,
    • K. Riles &
    • J. Sanders
  33. Charles Sturt University, Wagga Wagga, New South Wales 2678, Australia

    • P. Charlton
  34. Australian National University, Canberra, Australian Capital Territory 0200, Australia

    • B. C. Buchler,
    • J. H. Chow,
    • S. S. Y Chua,
    • R. Inta,
    • P. K. Lam,
    • D. E. McClelland,
    • J. Miller,
    • T. Nguyen,
    • S. M. Scott,
    • D. A. Shaddock,
    • B. J. J Slagmolen,
    • M. Stefszky,
    • A. Stochino,
    • A. Wade &
    • R. L. Ward
  35. The University of Melbourne, Parkville, Victoria 3010, Australia

    • C. T. Y. Chung,
    • P. D. Lasky,
    • A. Melatos &
    • L. Sammut
  36. Cardiff University, Cardiff CF24 3AA, UK

    • T. Adams,
    • M. Edwards,
    • S. Fairhurst,
    • E. Macdonald,
    • D. M. Macleod,
    • C. Messenger,
    • L. K. Nuttall,
    • F. Ohme,
    • V. Predoi,
    • B. S. Sathyaprakash,
    • B. F. Schutz,
    • P. J. Sutton &
    • J. Veitch
  37. University of Salerno, I- 84084 Fisciano (Salerno), and INFN (Sezione di Napoli), Italy

    • F. Postiglione
  38. The University of Sheffield, Sheffield S10 2TN, UK

    • E. J. Daw,
    • C. Tomlinson &
    • D. J. White
  39. Inter-University Centre for Astronomy and Astrophysics, Pune – 11007, India

    • S. Dhurandhar,
    • S. Mitra &
    • T. Souradeep
  40. Southern University and A&M College, Baton Rouge, Louisiana 70813, USA

    • S. C. McGuire &
    • R. Vincent-Finley
  41. University of Minnesota, Minneapolis, Minnesota 55455, USA

    • S. Kandhasamy,
    • A. Kremin,
    • V. Mandic &
    • T. Prestegard
  42. California Institute of Technology, Pasadena, California 91125, USA

    • R. W. P. Drever
  43. Northwestern University, Evanston, Illinois 60208, USA

    • B. F. Farr,
    • W. Farr,
    • D. Fazi,
    • Y. J. Jang,
    • V. Kalogera,
    • C. Rodriguez,
    • M. S. Shahriar,
    • D. Stevens,
    • M. V. van der Sluys,
    • J. Yablon &
    • H. Yum
  44. The University of Texas at Austin, Austin, Texas 78712, USA

    • R. A. Matzner &
    • L. Rodriguez
  45. MTA–Eotvos University, Lendulet A. R. G., Budapest 1117, Hungary

    • Z. Frei,
    • G. Gelencser &
    • G. Szeifert
  46. Embry–Riddle Aeronautical University, Prescott, Arizona 86301, USA

    • A. M. Gretarsson,
    • B. Hughey,
    • E. Jesse,
    • K. Loew &
    • M. Zanolin
  47. National Astronomical Observatory of Japan, Tokyo 181-8588, Japan

    • M-K. Fujimoto,
    • K. Hayama,
    • K. Izumi,
    • S. Kawamura,
    • T. Mori,
    • E. Nishida &
    • A. Nishizawa
  48. University of Adelaide, Adelaide, South Australia 5005, Australia

    • J. Munch,
    • D. J. Ottaway &
    • P. J. Veitch
  49. Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain

    • J. Burguet-Castell,
    • S. Gil-Casanova &
    • A. M. Sintes
  50. University of Southampton, Southampton SO17 1BJ, UK

    • D. I. Jones
  51. Institute of Applied Physics, Nizhny Novgorod 603950, Russia

    • E. A. Khazanov &
    • A. Sergeev
  52. SUPA, University of Strathclyde, Glasgow G1 1XQ, UK

    • N. A. Lockerbie &
    • K. V. Tokmakov
  53. Abilene Christian University, Abilene Texas 79699, USA

    • J. L. Willis
  54. Hobart and William Smith Colleges, Geneva, New York 14456, USA

    • R. Kasturi &
    • S. Penn
  55. University of Sannio at Benevento, I-82100 Benevento, and INFN (Sezione di Napoli), Italy

    • P. Addesso,
    • R. DeSalvo,
    • V. Pierro &
    • I. M. Pinto
  56. Louisiana Tech University, Ruston, Louisiana 71272, USA

    • T. Reed &
    • N. Zotov
  57. Andrews University, Berrien Springs, Michigan 49104, USA

    • T. Z. Summerscales
  58. McNeese State University, Lake Charles, Louisiana 70609, USA

    • G. Santostasi
  59. California State University Fullerton, Fullerton, California 92831, USA

    • C. Griffo,
    • B. J. Kuper,
    • J. Lee,
    • F. Magaña-Sandoval,
    • C. Padilla &
    • J. R. Smith
  60. Trinity University, San Antonio, Texas 78212, USA

    • D. Ugolini
  61. Rochester Institute of Technology, Rochester, New York 14623, USA

    • A. D. Castiglia,
    • M. A. Frei,
    • S. R. P. Mohapatra &
    • J. T. Whelan
  62. Southeastern Louisiana University, Hammond, Louisiana 70402, USA

    • W. Parkinson &
    • S. Yoshida
  63. Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario M5S 3H8, Canada

    • K. Cannon
  64. Pusan National University, Busan 609-735, Korea

    • H-S. Cho,
    • Y-M. Kim &
    • C-H. Lee
  65. West Virginia University, Morgantown, West Virginia 26505, USA

  66. Hanyang University, Seoul 133-791, Korea

    • K. Kim &
    • H. K. Lee
  67. Korea Institute of Science and Technology Information, Daejeon 305-806, Korea

    • H. Jang,
    • G. Kang,
    • B. K. Kim &
    • C. Kim
  68. National Institute for Mathematical Sciences, Daejeon 305-390, Korea

    • J. J. Oh,
    • S. H. Oh &
    • E. J. Son
  69. Seoul National University, Seoul 151-742, Korea

    • H. M. Lee
  70. University of Szeged, 6720 Szeged, Dóm tér 9, Hungary

    • L. Á. Gergely
  71. Perimeter Institute for Theoretical Physics, Ontario N2L 2Y5, Canada

    • C. Hanna
  72. University of New Hampshire, Durham, New Hampshire 03824, USA

    • M. Holtrop
  73. University of Cambridge, Cambridge CB2 1TN, UK

    • M. W. Coughlin &
    • J. Gair
  74. American University, Washington, DC 20016, USA

    • G. M. Harry
  75. Instituto Nacional de Pesquisas Espaciais, 12227-010 – São José dos Campos, SP, Brazil

    • O. D. Aguiar,
    • M. Constancio Junior &
    • C. A. Costa
  76. University of Washington, Seattle, Washington 98195-4290, USA

    • K. Venkateswara
  77. National Tsing Hua University, Hsinchu Taiwan 300, China

    • S. Chao,
    • V. Huang,
    • J. Ou &
    • J. Wang
  78. SUPA, University of the West of Scotland, Paisley PA1 2BE, UK

    • S. Reid
  79. The George Washington University, Washington, DC 20052, USA

    • A. Corsi
  80. Raman Research Institute, Bangalore, Karnataka 560080, India

    • B. R. Iyer
  81. Universidad Nacional de Cordoba, Cordoba 5000, Argentina

    • C. Kozameh
  82. IISER-Kolkata, Mohanpur West, Bengal 741252, India

    • R. Nayak
  83. IISER–TVM, CET Campus, Trivandrum Kerala 695016, India

    • K. Haris &
    • A. Pai
  84. RRCAT, Indore MP 452013, India

    • S. Raja
  85. Indian Institute of Technology, Gandhinagar Ahmedabad Gujarat 382424, India

    • A. S. Sengupta
  86. Tata Institute for Fundamental Research, Mumbai 400005, India

    • C. S. Unnikrishnan

Contributions

The activities of the LIGO Scientific Collaboration (LSC) include modelling astrophysical sources of gravitational waves, setting sensitivity requirements for observatories, designing, building and running observatories, carrying out research and development of new techniques to increase the sensitivity of these observatories, and performing searches for astrophysical signals contained in the data. S. Dwyer, S. Chua, L. Barsotti and D. Sigg were the leading scientists on this experiment, but a number of LSC members contributed directly to its success. M. Stefszky, A. Khalaidovski, M. Factourovich and C. Mow-Lowry assisted with the development of the squeezed vacuum source under the leadership of N. Mavalvala, D. McClelland and R. Schnabel. K. Kawabe supervised the integration of the squeezed vacuum source into the LIGO interferometer, with invaluable support from M. Landry and the LIGO Hanford Observatory staff. N. Smith-Lefebvre, M. Evans, R. Schofield and C. Vorvick kept the LIGO interferometer at its peak sensitivity and supported the integration of the squeezed vacuum source, with contributions from G. Meadors and D. Gustafson. The initial manuscript was written by L. Barsotti, N. Mavalvala, D. Sigg and D. McClelland. The LSC review of the manuscript was organized by S. Whitcomb. All authors approved the final version of the manuscript.

Competing financial interests

The authors declare no competing financial interests.

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