Dark Matter Searches on a Photonic Chip
Dark Matter (DM) with feeble couplings to electromagnetism can act as a
source of laboratory electromagnetic (EM) fields. A classic technique
for searching for this effect is the cavity haloscope where a
high-quality mode of an EM cavity is excited by the DM if the mode
frequency matches the DM mass. For example, the flagship axion DM
search, ADMX, uses radio frequency cavities to look for DM with masses
at the micro-eV scale. At higher DM masses, the required cavity size
becomes prohibitively small. I will review the requirements for
implementing efficient DM-photon conversion in a physical system. I will
then show that detectors based on integrated photonics (optical and
near-infrared waveguides and resonators at the micron scale) provide a
new, useful way to search for DM at these higher masses. In particular,
I will focus on refractive index-modulated resonators, such as grooved
or periodically-poled microrings, or patterned slabs. When excited by
the DM, EM modes in these structures can be read out by coupling the
resonators to a waveguide that terminates on a micron-scale-sized single
photon detector. These types of devices are practically important in,
e.g., sensing, telecommunications and quantum information science,
allowing us to leverage developments from those fields, including mass
production of these structures. Thus, a large number of detectors can be
used to implement a very sensitive DM search. Finally, I will estimate
the sensitivity of this approach to axion and dark photon DM.