GQuEST combines established techniques from the LIGO and the Fermilab Holometer interferometers with the latest technological advances of low-noise photon counters.
The project is working toward a technology demonstrator, which will be a power-recycled interferometer. This will provide the collaboration a platform to demonstrate and test innovative technologies.
Technical opportunities include:
Control of laser source and optics
Building on the experience of LIGO and the Holometer, the collaboration plans to implement control systems on commercially available FPGA hardware such as the Xilinx RFSoC. Making these well-tested algorithms available on more platforms will benefit other projects.
Mirror substrates and coatings to reduce noise
The bulk physical motion of mirror substrates introduces noise. Similarly, Brownian motion within the coatings is a separate noise source. Building on decades of experience from LIGO, GQuEST researchers will procure optics and demonstrate their superior noise performance in the Technology Demonstrator.
Carefully tuned optical cavities to form the narrow bandpass filter
An essential part of our experimental strategy is to filter out light at the laser wavelengths and allow photons converted by the quantum gravity effects. We are constructing bowtie cavities to achieve over 100 dB isolation.
Rejection of photons from thermal backgrounds to achieve low background rates
At our expected low count rates, thermal background photons from the optics at room temperature (or perhpas at 100 kelvin) need to be filtered while allowing photons near the laser wavelength to pass to the millikelvin detectors. GQuEST researchers will build and demonstrate a cryogenic fiber system to collect, filter, and deliver light.
Efficient detection and counting of individual photons
The SNSPD technology under development at JPL for a variety of other projects is a natural match to our requirements. Researchers will demonstrate control and readout of these detectors.