Comment on ''Quantum sensor networks as exotic field telescopes for multi-messenger astronomy''

TL;DR

This paper critiques prior claims that quantum sensor networks can detect certain astrophysical scalar waves, highlighting the overlooked back-action effects that can hinder detection and multi-messenger astronomy.

Contribution

It reveals the importance of back-action effects in scalar wave detection, challenging previous optimistic assessments of quantum sensor networks for multi-messenger astronomy.

Findings

Back-action causes screening of scalar waves near Earth's surface.

Back-action delays scalar wave propagation, affecting detection timing.

Detection prospects are significantly reduced due to back-action effects.

Abstract

In the recent work [Dailey et al., Nature Astronomy 5, 150 (2021)], it was claimed that networks of quantum sensors can be used as sensitive multi-messenger probes of astrophysical phenomena that produce intense bursts of relativistic bosonic waves which interact non-gravitationally with ordinary matter. The most promising possibility considered in [Ibid.] involved clock-based searches for quadratic scalar-type interactions, with greatly diminished reach in the case of magnetometer-based searches for derivative-pseudoscalar-type interactions and clock-based searches for linear scalar-type interactions. In this note, we point out that the aforementioned work overlooked the ''back action'' of ordinary matter on scalar waves with quadratic interactions and that accounting for back-action effects can drastically affect the detection prospects of clock networks. In particular, back action can cause strong screening of scalar waves near Earth's surface and by the apparatus itself, rendering clock experiments insensitive to extraterrestrial sources of relativistic scalar waves. Additionally, back-action effects can retard the propagation of scalar waves through the interstellar and intergalactic media, significantly delaying the arrival of scalar waves at Earth compared to their gravitational-wave counterparts and thereby preventing multi-messenger astronomy on human timescales.