N. A. Holland
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View article: Non-Smooth Multi-Objective Controller Synthesis for Test-Mass Actuation in Gravitational-Wave Detectors
Non-Smooth Multi-Objective Controller Synthesis for Test-Mass Actuation in Gravitational-Wave Detectors Open
This paper proposes a non-smooth controller optimization method and shows the results of ongoing research on the implementation of this method for gravitational-wave applications. Typical performance requirements concerning these type of s…
View article: Integration of High-performance Compact Interferometric Sensors in a Suspended Interferometer
Integration of High-performance Compact Interferometric Sensors in a Suspended Interferometer Open
Homodyne Quadrature Interferometers (HoQIs) are compact, low noise and high dynamic range displacement sensors designed for use in gravitational wave observatories. Their lower noise compared to the displacement sensors used at present mak…
View article: Multi-scale optimal control for Einstein Telescope active seismic isolation
Multi-scale optimal control for Einstein Telescope active seismic isolation Open
We present a multi-scale optimal control framework for active seismic isolation in the Einstein Telescope, a third-generation gravitational-wave observatory. Our approach jointly optimizes feedback and blending filters in a cross-coupled o…
View article: Non-Smooth Multi-objective Controller Synthesis for Test-Mass Actuation in Gravitational-Wave Detectors
Non-Smooth Multi-objective Controller Synthesis for Test-Mass Actuation in Gravitational-Wave Detectors Open
This paper proposes a non-smooth controller optimization method and shows the results of ongoing research on the implementation of this method for gravitational wave applications. Typical performance requirements concerning these type of s…
View article: Advanced LIGO detector performance in the fourth observing run
Advanced LIGO detector performance in the fourth observing run Open
On May 24, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The LI…
View article: Advanced LIGO detector performance in the fourth observing run
Advanced LIGO detector performance in the fourth observing run Open
On May 24th, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The …
View article: Characterization of heterodyne optical phase locking for relative laser frequency noise suppression in differential measurement
Characterization of heterodyne optical phase locking for relative laser frequency noise suppression in differential measurement Open
Laser frequency noise is particularly challenging to mitigate in low Fourier frequency measurement. For differential measurement schemes using heterodyne optical phase-locked loops, this noise can be common-mode suppressed in the final rea…
View article: Integration of high-performance compact interferometric sensors in a suspended interferometer
Integration of high-performance compact interferometric sensors in a suspended interferometer Open
Homodyne Quadrature Interferometers (HoQIs) are compact, low noise and high dynamic range displacement sensors designed for use in gravitational wave observatories. Their lower noise compared to the displacement sensors used at present mak…
View article: Laser frequency stabilization with the use of homodyne quadrature interferometers
Laser frequency stabilization with the use of homodyne quadrature interferometers Open
Laser frequency stabilization is a crucial technique for precision metrology. We demonstrate laser frequency control using a compact, interferometric sensor, specially modified for sensitivity to laser frequency noise. This setup achieves …
View article: Broadband Quantum Enhancement of the LIGO Detectors with Frequency-Dependent Squeezing
Broadband Quantum Enhancement of the LIGO Detectors with Frequency-Dependent Squeezing Open
Quantum noise imposes a fundamental limitation on the sensitivity of interferometric gravitational-wave detectors like LIGO, manifesting as shot noise and quantum radiation pressure noise. Here, we present the first realization of frequenc…
View article: A vacuum-compatible cylindrical inertial rotation sensor with picoradian sensitivity
A vacuum-compatible cylindrical inertial rotation sensor with picoradian sensitivity Open
We describe an inertial rotation sensor with a 30-cm cylindrical proof-mass suspended from a pair of 14 μm thick BeCu flexures. The angle between the proof-mass and support structure is measured with a pair of homodyne interferometers, whi…
View article: A Vacuum-Compatible Cylindrical Inertial Rotation Sensor with Picoradian Sensitivity
A Vacuum-Compatible Cylindrical Inertial Rotation Sensor with Picoradian Sensitivity Open
We describe an inertial rotation sensor with a 30-cm cylindrical proof-mass suspended from a pair of 14-$μ$m thick BeCu flexures. The angle between the proof-mass and support structure is measured with a pair of homodyne interferometers wh…
View article: Publisher’s Note: “Reducing control noise in gravitational wave detectors with interferometric local damping of suspended optics” [Rev. Sci. Instrum. 94, 054501 (2023)]
Publisher’s Note: “Reducing control noise in gravitational wave detectors with interferometric local damping of suspended optics” [Rev. Sci. Instrum. 94, 054501 (2023)] Open
This article was originally published online on 16 May 2023 with incorrect figure references. The references have been corrected. AIP Publishing apologizes for this error. All online versions of the article were corrected on 23 May 2023; t…
View article: The torsion pendulum dual oscillator for low-frequency Newtonian noise detection
The torsion pendulum dual oscillator for low-frequency Newtonian noise detection Open
We present a torsion pendulum dual oscillator sensor designed toward the direct detection of Newtonian noise. We discuss the sensitivity limitations of the system, experimental performance characterization results, and prospectives to impr…
View article: Searching for the causes of anomalous Advanced LIGO noise
Searching for the causes of anomalous Advanced LIGO noise Open
Advanced LIGO and Advanced Virgo have detected gravitational waves from astronomical sources to open a new window on the Universe. To explore this new realm requires an exquisite level of detector sensitivity, meaning that the much stronge…
View article: Reducing control noise in gravitational wave detectors with interferometric local damping of suspended optics
Reducing control noise in gravitational wave detectors with interferometric local damping of suspended optics Open
Control noise is a limiting factor in the low-frequency performance of the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO). In this paper, we model the effects of using new sensors called Homodyne Quadrature Interferome…
View article: Reducing controls noise in gravitational wave detectors with interferometric local damping of suspended optics
Reducing controls noise in gravitational wave detectors with interferometric local damping of suspended optics Open
Control noise is a limiting factor in the low-frequency performance of the LIGO gravitational wave detectors. In this paper we model the effects of using new sensors called HoQIs to control the suspension resonances. We show if we were to …
View article: LIGO’s quantum response to squeezed states
LIGO’s quantum response to squeezed states Open
Gravitational 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 o…
View article: Point absorbers in Advanced LIGO
Point absorbers in Advanced LIGO Open
Small, highly absorbing points are randomly present on the surfaces of the main interferometer optics in Advanced LIGO. The resulting nanometer scale thermo-elastic deformations and substrate lenses from these micron-scale absorbers signif…
View article: Reducing scattered light in LIGO’s third observing run
Reducing scattered light in LIGO’s third observing run Open
Noise due to scattered light has been a frequent disturbance in the advanced LIGO gravitational wave detectors, hindering the detection of gravitational waves. The non stationary scatter noise caused by low frequency motion can be recogniz…
View article: Point Absorber Limits to Future Gravitational-Wave Detectors
Point Absorber Limits to Future Gravitational-Wave Detectors Open
High-quality optical resonant cavities require low optical loss, typically on the scale of parts per million. However, unintended micron-scale contaminants on the resonator mirrors that absorb the light circulating in the cavity can deform…
View article: Practical test mass and suspension configuration for a cryogenic kilohertz gravitational wave detector
Practical test mass and suspension configuration for a cryogenic kilohertz gravitational wave detector Open
Designs for future gravitational wave detection facilities feature silicon test masses at cryogenic temperatures to reduce thermal noise and thermally induced aberrations. Designers call for operation at 123 K or close to 18 K to exploit t…
View article: Sensitivity and performance of the Advanced LIGO detectors in the third observing run
Sensitivity and performance of the Advanced LIGO detectors in the third observing run Open
On April 1st, 2019, the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO), joined by the Advanced Virgo detector, began the third observing run, a year-long dedicated search for gravitational radiation. The LIGO detector…
View article: Quantum correlations between light and the kilogram-mass mirrors of LIGO
Quantum correlations between light and the kilogram-mass mirrors of LIGO Open
© 2020, The Author(s), under exclusive licence to Springer Nature Limited. The measurement of minuscule forces and displacements with ever greater precision is inhibited by the Heisenberg uncertainty principle, which imposes a limit to the…
View article: Quantum-Enhanced Advanced LIGO Detectors in the Era of Gravitational-Wave Astronomy
Quantum-Enhanced Advanced LIGO Detectors in the Era of Gravitational-Wave Astronomy Open
The Laser Interferometer Gravitational Wave Observatory (LIGO) has been directly detecting gravitational waves from compact binary mergers since 2015. We report on the first use of squeezed vacuum states in the direct measurement of gravit…
View article: Early Earthquake Detection with a Dual Torsion-Beam Gravimeter
Early Earthquake Detection with a Dual Torsion-Beam Gravimeter Open
Ground mass is redistributed during an earthquake causing the local gravitational potential to change. These gravitational fluctuations travel at the speed of light meaning they will arrive at a remote location significantly earlier than t…