Intensity interferometry for ultralight bosonic dark matter detection

Abstract

Ultralight bosonic dark matter (UBDM) can be described by a classical wave-like field oscillating at the Compton frequency of the bosons. If a measurement scheme for the direct detection of UBDM interactions is sensitive to a signature quadratic in the field, then there is a near-zero-frequency (dc) component of the signal. Thus, a detector with a given finite bandwidth can be used to search for bosons with Compton frequencies many orders of magnitude larger than its bandwidth. This opens the possibility of a detection scheme analogous to Hanbury Brown and Twiss interferometry. Assuming that the UBDM is virialized in the gravitational potential, for example of the Milky Way, the random velocities produce slight deviations from the Compton frequency. These result in stochastic fluctuations of the intensity on a time scale determined by the spread in velocities. In order to mitigate ubiquitous local low-frequency noise, a network of sensors can be used to search for the stochastic intensity fluctuations by measuring cross-correlation between the sensors. This method is inherently broadband, since a large range of Compton frequencies will have a nearzero-frequency component within the sensor bandwidth that can be searched for simultaneously. Experiments with existing clock and magnetometer networks have sufficient sensitivity to search a broad range of unexplored parameter space.

Measuring the Quantum State of Dark Matter

“…A coherent state virialized model like the one expressed in Equation ( 1) is explicitly assumed in many UBDM direct detection data analyses, including refs. [37,38], and the model is implemented in the AxiScan data analysis software. [36,39]…”

What Can a GNOME Do? Search Targets for the Global Network of Optical Magnetometers for Exotic Physics Searches

“…Furthermore, there are novel experimental signatures and modalities that can be employed to search for the quadraticin-𝜑 interactions. [72] The Lagrangian describing the quadratic gradient coupling between an ALP field and atomic spins is given by [36]…”

“…Given the close analogy between the behavior of virialized ALP fields and thermal light, we can take full advantage of the fact that GNOME is a network of spatially distributed sensors by implementing a detection scheme similar to Hanburry-Brown-and-Twiss intensity interferometry [157] as recently proposed in ref. [72]. The quadratic ALP interaction with spins (Equation ( 9)) leads to a signal in GNOME magnetometers related to the intensity of the ALP field, 𝜑 2 (r, t).…”

New Horizons: Scalar and Vector Ultralight Dark Matter

“…The geographically distributed array of GNOME magnetometers enables consistency checks based on the relative timing and amplitudes of signals, enabling vetoing of false-positive events and suppressing uncorrelated noise [551]. GNOME can also be used to search for correlated signals from stochastic fluctuations of bosonic dark matter fields [552] and bursts of exotic fields emanating from cataclysmic astrophysical events [553]. Importantly, correlated network searches offer the possibility to hunt for the unexpected.…”