1,721,128 research outputs found
The Quantum Limit and Beyond in Gravitational Wave Detectors
No full textMavalvala, Nergis. (2010). The Quantum Limit and Beyond in Gravitational Wave Detectors. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/96092
Gravitationally induced phase shift on a single photon
Full text linkThe effect of the Earth's gravitational potential on a quantum wave function has only been observed for massive particles. In this paper we present a scheme to measure a gravitationally induced phase shift on a single photon traveling in a coherent superposition along different paths of an optical fiber interferometer. To create a measurable signal for the interaction between the static gravitational potential and the wave function of the photon, we propose a variant of a conventional Mach–Zehnder interferometer. We show that the predicted relative phase difference of 10⁻⁵ rad is measurable even in the presence of fiber noise, provided additional stabilization techniques are implemented for each arm of a large-scale fiber interferometer. Effects arising from the rotation of the Earth and the material properties of the fibers are analysed. We conclude that optical fiber interferometry is a feasible way to measure the gravitationally induced phase shift on a single-photon wave function, and thus provides a means to corroborate the equivalence of the energy of the photon and its effective gravitational mass
Gravitational wave detector with cosmological reach
Full text linkTwenty years ago, construction began on the Laser Interferometer Gravitational-wave Observatory (LIGO). Advanced LIGO, with a factor of 10 better design sensitivity than Initial LIGO, will begin taking data this year, and should soon make detections a monthly occurrence. While Advanced LIGO promises to make first detections of gravitational waves from the nearby universe, an additional factor of 10 increase in sensitivity would put exciting science targets within reach by providing observations of binary black hole inspirals throughout most of the history of star formation, and high signal to noise observations of nearby events. Design studies for future detectors to date rely on significant technological advances that are futuristic and risky. In this paper we propose a different direction. We resurrect the idea of using longer arm lengths coupled with largely proven technologies. Since the major noise sources that limit gravitational wave detectors do not scale trivially with the length of the detector, we study their impact and find that 40 km arm lengths are nearly optimal, and can incorporate currently available technologies to detect gravitational wave sources at cosmological distances (z ≳ 7).National Science Foundation (U.S.) (Grant PHY-1352511)National Science Foundation (U.S.) (Grant PHY-0823459)National Science Foundation (U.S.) (Grant PHY-1068809
A continuously tunable modulation scheme for precision control of optical cavities with variable detuning
Full text linkWe present a scheme for locking optical cavities with arbitrary detuning many
line widths from resonance using an electro-optic modulator that can provide
arbitrary ratios of amplitude to phase modulation. We demonstrate our scheme on
a Fabry-Perot cavity, and show that a well-behaved linear error signal can be
obtained by demodulating the reflected light from a cavity that is detuned by
several line widths.Comment: 5 pages, 4 figure
Environmental noise in advanced LIGO detectors
No full textThe sensitivity of the Advanced LIGO detectors to gravitational waves can be
affected by environmental disturbances external to the detectors themselves.
Since the transition from the former initial LIGO phase, many improvements have
been made to the equipment and techniques used to investigate these
environmental effects. These methods have aided in tracking down and mitigating
noise sources throughout the first three observing runs of the advanced
detector era, keeping the ambient contribution of environmental noise below the
background noise levels of the detectors. In this paper we describe the methods
used and how they have led to the mitigation of noise sources, the role that
environmental monitoring has played in the validation of gravitational wave
events, and plans for future observing runs
Report to the President for year ended June 30, 2022, Dean, School of Science
No full textThis report contains the following sections: Diversity, Equity, and Inclusion; Computing Infrastructure; Life Sciences Centers; Education; Open Learning; Research; Awards and Honors; Personne
Point absorbers in Advanced LIGO
No full textSmall, highly absorbing points are randomly present on the surfaces of the
main interferometer optics in Advanced LIGO. The resulting nano-meter scale
thermo-elastic deformations and substrate lenses from these micron-scale
absorbers significantly reduces the sensitivity of the interferometer directly
though a reduction in the power-recycling gain and indirect interactions with
the feedback control system. We review the expected surface deformation from
point absorbers and provide a pedagogical description of the impact on power
build-up in second generation gravitational wave detectors (dual-recycled
Fabry-Perot Michelson interferometers). This analysis predicts that the
power-dependent reduction in interferometer performance will significantly
degrade maximum stored power by up to 50% and hence, limit GW sensitivity, but
suggests system wide corrections that can be implemented in current and future
GW detectors. This is particularly pressing given that future GW detectors call
for an order of magnitude more stored power than currently used in Advanced
LIGO in Observing Run 3. We briefly review strategies to mitigate the effects
of point absorbers in current and future GW wave detectors to maximize the
success of these enterprises
LIGO’s quantum response to squeezed states
No full textGravitational Wave interferometers achieve their profound sensitivity by
combining a Michelson interferometer with optical cavities, suspended masses,
and now, squeezed quantum states of light. These states modify the measurement
process of the LIGO, VIRGO and GEO600 interferometers to reduce the quantum
noise that masks astrophysical signals; thus, improvements to squeezing are
essential to further expand our gravitational view of the universe. Further
reducing quantum noise will require both lowering decoherence from losses as
well more sophisticated manipulations to counter the quantum back-action from
radiation pressure. Both tasks require fully understanding the physical
interactions between squeezed light and the many components of km-scale
interferometers. To this end, data from both LIGO observatories in observing
run three are expressed using frequency-dependent metrics to analyze each
detector's quantum response to squeezed states. The response metrics are
derived and used to concisely describe physical mechanisms behind squeezing's
simultaneous interaction with transverse-mode selective optical cavities and
the quantum radiation pressure noise of suspended mirrors. These metrics and
related analysis are broadly applicable for cavity-enhanced optomechanics
experiments that incorporate external squeezing, and -- for the first time --
give physical descriptions of every feature so far observed in the quantum
noise of the LIGO detectors
LIGO detector characterization in the second and third observing runs
No full textAbstract
The characterization of the Advanced LIGO detectors in the second and third observing runs has increased the sensitivity of the instruments, allowing for a higher number of detectable gravitational-wave signals, and provided confirmation of all observed gravitational-wave events. In this work, we present the methods used to characterize the LIGO detectors and curate the publicly available datasets, including the LIGO strain data and data quality products. We describe the essential role of these datasets in LIGO–Virgo Collaboration analyses of gravitational-waves from both transient and persistent sources and include details on the provenance of these datasets in order to support analyses of LIGO data by the broader community. Finally, we explain anticipated changes in the role of detector characterization and current efforts to prepare for the high rate of gravitational-wave alerts and events in future observing runs.</jats:p
Alignment issues in laser interferometric gravitational-wave detectors
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1997.Includes bibliographical references (p. 107-109).by Nergis Mavalvala.Ph.D
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