Quantum enhanced metrology in the search for fundamental physical phenomena

TL;DR

This paper reviews how quantum metrology, especially quantum squeezing, enhances searches for ultralight dark matter by improving sensitivity in experiments where dark matter interacts as a weak classical force, even with unknown particle mass.

Contribution

It applies quantum metrology techniques to dark matter detection, demonstrating benefits of quantum squeezing in experiments with uncertain dark matter mass.

Findings

Quantum squeezing improves detection sensitivity for ultralight dark matter.

Quantum metrology techniques are effective even when dark matter signals are more coherent than the measuring oscillator.

The approach benefits microwave frequency searches for axion-like particles.

Abstract

These notes summarize lectures given at the 2019 Les Houches summer school on Quantum Information Machines. They describe and review an application of quantum metrology concepts to searches for ultralight dark matter. In particular, for ultralight dark matter that couples as a weak classical force to a laboratory harmonic oscillator, quantum squeezing benefits experiments in which the mass of the dark matter particle is unknown. This benefit is present even if the oscillatory dark matter signal is much more coherent than the harmonic oscillator that it couples to, as is the case for microwave frequency searches for dark matter axion particles.