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

Abstract

Nearly a century after Einstein first predicted the existence of gravitational waves, a global network of Earth-based gravitational wave observatories [1, 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

Enhancement and state tomography of a squeezed vacuum with circuit quantum electrodynamics

“…The ability to produce high-quality squeezed electromagnetic states is a valuable resource for applications in high-precision measurements of weak signals such as gravitational waves [35]; development of higher signal-to-noise communication protocols [36]; and provides a source of entangled photons for quantum technology such as key distribution [37]. At optical wavelengths, squeezing of 12.7 dB below vacuum noise can now be achieved in a beam [38], but squeezing of an intracavity field has not been directly measured.…”

Frequentist and Bayesian Quantum Phase Estimation

“…Quantum noise cannot be fully suppressed, even in the idealized case of the creation and manipulation of pure quantum states. Using classically-correlated probe states, it is possible to reach the so-called shot noise or standard quantum limit, which is the limiting factor for the current generation of interferometers and sensors [9][10][11][12]. Strategies involving probe states characterized by squeezed quadratures [13] or entanglement between particles [14][15][16][17][18][19] are able to overcome the shot noise, the ultimate quantum bound being the so-called Heisenberg limit.…”

Towards thermal noise free optomechanics

“…Optomechanics, the interaction of photons with phonons, is a phenomenon that allows for sensitive measurements close to fundamental limits [1].One example of extremely precise measurement using optomechanics is the detection of gravitational waves in large interferometers [2,3]. Optomechanics can also be used to impose and control quantum states on high frequency resonators at cryogenic temperatures [4][5][6].…”