A Novel Tabletop Gravitational-wave Detector for Frequencies > 10 kHz Phase II

The kilometer-scale Laser Interferometer Gravitational-Wave Observatory (LIGO) interferometers have just begun to detect gravitational waves (GWs), firmly establishing the nascent field of GW astronomy. It is paramount to study GW radiation across a wide frequency range, as astronomers have done for visible light and other electromagnetic radiation. While advanced LIGO has achieved remarkable sensitivity at frequencies ranging from 10s of Hz to a few kHz, no established methods can probe the higher frequency part of the spectrum, where undiscovered GW sources may exist, including primordial black holes and other well-motivated dark matter candidates. With support from the W. M. Keck Foundation’s Science and Engineering program, our Northwestern University team aims to develop and test a 1-meter prototype of a novel (GW) detector, based on optically-levitated dielectric particles in an optical cavity. As shown in our concept paper (Phys. Rev. Lett. 110: 071105, 2013), the method could extend the search volume of advanced GW observatories by up to 1000 times in the high frequency (HF) range of 10-300 kHz, using an instrument that is a fraction of their size (~10 m). To realize the full sensitivity of the detector, we will need to demonstrate trapping and cooling of non-spherical, i.e., disc-like, particles in high vacuum. After initial tests, we will conduct a 1-year observing run using two detectors for frequencies > 10 kHz. The frequency coverage of this instrument complements existing and other proposed GW detectors and promises to enable a new HF-GW map of our universe.