Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session B09: Next-Generation Gravitational Wave Detectors |
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Sponsoring Units: DGRAV Chair: Emanuele Berti, Johns Hopkins University Room: Conrad B/C - 2nd Floor |
Saturday, April 15, 2023 10:45AM - 10:57AM |
B09.00001: Experimental investigations on the Higher-order Hermite-Gauss mode interferometry Liu Tao, Paul J Fulda Thermal noise of the test masses is one of the limiting noise sources in advanced gravitational wave (GW) detectors. It is expected to remain a limiting noise source in future detectors, despite radical changes to the design including cryogenic operations, new materials, and the use of longer laser wavelengths. The so-called "flat beams" such as higher-order Hermite-Gaussian (HG) beams have been studied for thermal noise reduction in GW detectors. They help by better averaging over the random mirror surface fluctuations caused by thermal motions. We have started the experimental investigations on the HG mode interferometry with HG3,3 mode, and we will report on the latest results and progress. |
Saturday, April 15, 2023 10:57AM - 11:09AM |
B09.00002: Guided Matter-Wave Resonant Atom Interferometry for Gravitational-Wave Detectors Grant D Meadors, Changhyun Ryu, Kevin C Henderson Atom interferometry could complement existing and future laser-interferometric gravitational-wave observatories: this presentation describes a new experimental technique, guided matter waves, to enhance resonant atom-interferometer performance. Building on an existing tabletop atom interferometer at Los Alamos National Laboratory, two Rubidium-87 clouds are interrogated for more than 40 ms, to yield acceleration measurements better than 8 micro-g. This experiment aims for 1-s interrogation times (already reaching 150 ms). Differential detection with lock-in amplification is expected to significantly reduce seismic coupling in the 100-mHz to 10-Hz band. Using guided matter waves, resonant atom interferometer designs could provide critical gravity-gradiometry measurements in compact sensors, without the need for large free-fall towers. This technology could support Cosmic Explorer and Einstein Telescope, potentially facilitating noise cancellation of limiting constraints on low-frequency sensitivity in the band between LISA and next-generation ground-based observatories. Guided matter-wave resonant atom interferometers might also offer direct gravitational-wave astrophysical measurements at specific, narrowband frequency ranges. |
Saturday, April 15, 2023 11:09AM - 11:21AM |
B09.00003: An optomechanical instrumentation amplifier with intracavity radiation pressure mediated gain Aaron Markowitz, Shruti Maliakal, Christopher Wipf, rana X adhikari Quantum metrology applications leveraging highly squeezed states of light, including next-generation gravitational wave detectors, can be limited by mode-matching, photodetection, and other optical losses in the readout chain. Phase-sensitive ponderomotive pre-amplification can protect quantum noise limited signals from such downstream losses without introducing excess input-referred loss. We describe a tabletop traveling wave cavity in which a 1550nm pump tuned on-resonance coherently mixes with amplitude sidebands of a homodyne probe field to drive a gram-scale silicon resonator. The resulting cavity length fluctuations induce phase fluctuations in the reflected pump, which are sensed through Pound-Drever-Hall locking. We present the audio-band gain performance and noise budget of the initial demonstration. Ongoing work may bring the amplifier’s input-referred noise well below vacuum shot noise by canceling pump relative intensity noise through a balanced Mach-Zehnder configuration and reducing thermal noise through cryogenic (123K) operation.
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Saturday, April 15, 2023 11:21AM - 11:33AM |
B09.00004: Testing of a Prototype Optical Truss Interferometer for the LISA Telescope Kylan M Jersey, Yanqi Zhang, Ian Harley-Trochimczyk, Felipe Guzman The LISA telescopes are bidirectional components used to send and receive laser light between the three LISA spacecraft, each separated by 2.5 million km in a triangular constellation, to form long baseline interferometers between free flying test masses aboard each spacecraft. These telescopes lie directly in the optical path of the interferometers, and so their optical path length stability must exhibit a pm/√Hz noise level at mHz frequencies to allow for the detection of incoming gravitational waves. One method to monitor and verify the displacement noise along the optical path of the telescope is the implementation of an optical truss interferometer (OTI), which consists of three Fabry-Perot cavities mounted lengthwise around the telescope structure. We have developed prototype OTI cavities formed by compact input and return stages which integrate fiber injection, mode matching, and cavity mirrors into modular units housed in Zerodur and mounted to a test structure. The path length stability is monitored via Pound-Drever-Hall (PDH) frequency locking such that the laser frequency locked to each optical cavity will change in proportion to displacements in the test structure. The laser frequencies are measured as beat signals with respect to a reference frequency generated by a master laser locked to a stable reference cavity. We have tested our prototype OTI cavities to verify a pm/√Hz displacement sensitivity, and we will present on our experimental setup and initial results. |
Saturday, April 15, 2023 11:33AM - 11:45AM |
B09.00005: UF Length Stability Testing for the LISA Telescope Structural Thermal Model Alexander J Weaver The Laser Interferometry Space Antenna (LISA) is an upcoming space-based ESA lead gravitational wave (GW) detection mission, with high sensitivity in the milliHertz GW gap left between earth based GW detectors and pulsar timing arrays. The mission consists of 3 spacecraft (SC) in heleocentric orbit, with exchanged laser beams between each pair of SC monitoring displacements at the level of picometers in the LISA band between housed test masses. This requires LISA's telescopes, provided by NASA, demonstrate picometer level stability along the optical path. To test this University of Florida's (UF) LISA Telescope team had developed procedures to measure length stability in a fully functional copy of the LISA telescope, the Engineering Developement Unit (EDU). These plans and methodologies were adapted due to scheduling to accomodate the testing of the more simple Structural Thermal Model (STM) of the telescope. This is a non-functional equivalent containing all bonds and mounting but none of the polished mirror surfaces. In this presentation I go over how we've adapted the original EDU testing procedures for STM length stability testing, and the current status of such tests. |
Saturday, April 15, 2023 11:45AM - 11:57AM |
B09.00006: Sideband Locking for the LISA Optical Truss Interferometer Readout Paul Edwards, Paul Fulda In LISA, the optical truss interferometer (OTI) is a subsystem proposed to track pathlength variations in the telescope and ensure the telescope structure meets the required picometer stability. An OTI would be located at each of the six LISA telescopes, with each OTI comprising three separate linear cavities in a triangular configuration. If a telescope is not picometer stable, on-mission cavity length measurements serve as a potential witness channel for spurious length fluctuations. A simple method of cavity length measurements would involve three separate lasers, each locked to a respective OTI cavity. However, one alternative which uses a pick-off from a single, pre-existing laser source at each telescope is sideband locking, which would lock pairs of sidebands to each of the three cavities. Via this sideband locking, a voltage-controlled oscillator (VCO) signal, applied to a broadband electro-optic modulator (EOM), is used to tune sideband frequencies, thus tracking cavity length without the requirement of additional laserheads. We report demonstrations of this scheme and plans for its development and optimization for use in the OTI. |
Saturday, April 15, 2023 11:57AM - 12:09PM |
B09.00007: Calculating the precision of tilt-to-length coupling estimation and noise subtraction in LISA using Fisher information Daniel George, Jose Sanjuan, Paul Fulda, Guido Mueller Tilt-to-length (TTL) noise from angular jitter in the Laser Interferometer Space Antenna (LISA) is projected to be the dominant noise source in the milli-Hertz band unless corrected in post-processing. The correction is only possible after removing the overwhelming laser phase noise using time-delay interferometry (TDI). We present here a frequency domain model that describes the effect of angular motion of all three spacecraft on the interferometric signals after propagating through TDI. We then apply a Fisher information matrix analysis to this model to calculate the minimum uncertainty with which TTL coupling coefficients may be estimated. Furthermore, we show the impact of these uncertainties on the residual TTL noise in the gravitational wave readout channel, and compare it to the impact of the angular witness sensors' readout noise. We show that the residual TTL noise post-subtraction in the TDI variables for a case using the LISA angular jitter requirement and integration time of one day is limited to the 8 pm/√Hz level by angular sensing noise. However, using a more realistic model for the angular jitter we find that the TTL coupling uncertainties are 70 times larger, and the noise subtraction is limited by these uncertainties to the 14 pm/√Hz level. |
Saturday, April 15, 2023 12:09PM - 12:21PM |
B09.00008: Long-term optical path-length stability testing of the LISA Telescope Structural Thermal Model Laura R Roberts The Laser Interferometry Space Antenna (LISA) is an upcoming space-based ESA lead gravitational wave (GW) detection mission, with high sensitivity in the milliHertz GW gap left between Earth based GW detectors and pulsar timing arrays. The mission consists of 3 spacecraft (SC) in heleocentric orbit, with exchanged laser beams between each pair of SC monitoring displacements at the level of picometers in the LISA band between housed test masses. This requires LISA's telescopes, provided by NASA, demonstrate picometer level stability along the optical path. University of Florida's LISA Telescope team will test the path-length stability of beams within the structural thermal model (STM) of the telescopes, a functional equivalent containing all bonds but none of the polished mirror surfaces. By introducing several cavity optics, we create two optical cavities within the STM which we will PDH lock to two beams. Beat notes of these against a laser locked to an ultrastable reference cavity should then provide the necessary CTE and stability information about the telescope optical path. Additionally, beatnotes with an iodine stabilized laser can yield infromation about long term drifts of the cavity length. In our presentation we go over the testing setup of these two frequency based stabilization techniques, and whatever results we can share from testing that are available to the public. |
Saturday, April 15, 2023 12:21PM - 12:33PM |
B09.00009: Ensuring Reliability in Space: Environmental Testing of a UV-LED Based Charge Management System for the LISA Gravitational Wave Observatory Simon F Barke, Corey Richardson, Ben Letson, Samantha P Kenyon, Guido Mueller, Timothy Sumner, Peter J Wass, Mark Storm, John Conklin The Laser Interferometer Space Antenna (LISA) mission represents a significant step forward in our understanding of gravitational waves and the universe. By utilizing a combination of laser interferometry and electrostatic sensing, LISA is able to accurately measure the position of free-falling test masses, serving as gravitational reference points in space. However, the operation of this revolutionary mission is dependent upon the stability of the electrical environment, which is maintained through the Charge Management System (CMS). Our team at the University of Florida has been contracted by NASA to develop a UV-LED based CMS, which utilizes photoemission under ultraviolet illumination to neutralize excess charges on the test masses. |
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