Cindy Regal: Quantum optomechanics in interferometry and transduction at https://www.youtube.com/watch?v=zY2xn7bhMY0
Cindy Regal, All that you said, applies to dynamic gravitational waves. I like your broadband note at 23:37 especially. But you can do a lot more. All the frequencies (femtoHertz to TeraHertz, and beyond in both directions) are available for “gravity” and usually detectable.
I have been asking “quantum” groups to check their “quantum noise” over days and weeks. Some of what gets classified as “kT” noise, or “zero point” or “1/f” or “baseline drift” can be traced to gravitational sources. For the Internet Foundation, tracking all global sensor networks and related technologies, a careful and complete framework is critical, not a nice to have.
With GigaSamplesPerSecond (Gsps) you can use gravitational and electromagnetic time of flight arrays and correlation imaging to test if a noise source is “magnetic”, “gravitational”, “electromagnetic”, “thermal”. To image the moon and sun, even 100 KHz is useful. I have been following the neutrino and cosmic ray groups for a while now, and their small signals are affected by the local gravitational potential, and sometimes by the local vector tidal gravity (a three axis nearly perfectly Newtonian signal). Atomic clocks and atom interferometers are chip size and slowly getting better amplifier stages for the small signals. There are many dozens of kinds of low cost gravimeters now, and they are mostly able to cover from milliHertz to MegaHertz (milliSps to MegaSps in ADC terms)
A universal method for signals – across all frequencies, energies, and types seems best. An FFT for “acoustic”, or “infrasound” or “soft x-ray” or “gamma ray” or “low frequencies from 3 Hertz down to 3 milliHertz” is an FFT. Once it is “data” or a “time series” you can combine any sets of different kinds of sensors and try to find correlations. You can use the same correlation node methods used for global scale electromagnetic interferometry with gravitational sources.
Any frequency where the wavelength is about equal to, or larger than, the earth can be detected now with global correlation networks. The newer “tensor” and “gravity gradiometer” instruments can fly in drones, planes and satellites. The gravimeters are using the whole earth as part of the detection, that is why you can use a modified MEMS accelerometer with better amplifiers to make it sensitive enough to track the sun and moon using the vector tidal gravity signal (look at a month long signal at a superconducting gravimeter station).
An earthquake will generate gravitational, magnetic, electric, electromagnetic signals, infrasound and other effects. The Japan earthquake registered on both the superconducting gravimeter and the seismic broadband three axis seismometers. But they can be extended several orders of magnitude now in frequency and in energy because of more and more off the shelf broadband low noise amplifiers, and off the shelf high bit size, high sampling rate ADCs.
All the “interferometry” methods work across all frequencies. There are people working in every SI prefix from quecto (10^-30) to Quetta (10^30) and beyond. To keep yourself from a lot of trouble remembering, always UpperCase your “big prefixes”. So it is MegaHertz and MegaSps. CamelCase will save you a lot of trouble and time reading and writing. People and AIs routinely use mJ when they really mean MegaJoules, so write it out.
Richard Collins, The Internet Foundation