A quantum-enhanced search for dark matter axions

TL;DR

This paper demonstrates a quantum-enhanced method using vacuum squeezing to double the search rate for dark matter axions in a specific mass range, setting new exclusion limits.

Contribution

It introduces the use of vacuum squeezing in microwave-frequency axion searches to surpass the quantum noise limit, improving detection sensitivity.

Findings

No axion signal detected in the searched mass range.

Achieved a twofold increase in search rate over previous methods.

Set new exclusion limits for axion-photon coupling at 90% confidence.

Abstract

In dark matter axion searches, quantum uncertainty manifests as a fundamental noise source, limiting the measurement of the quadrature observables used for detection. We use vacuum squeezing to circumvent the quantum limit in a search for a new particle. By preparing a microwave-frequency electromagnetic field in a squeezed state and near-noiselessly reading out only the squeezed quadrature, we double the search rate for axions over a mass range favored by recent theoretical projections. We observe no signature of dark matter axions in the combined $16.96-17.12$ and $17.14-17.28\space\mu\text{eV}/c^2$ mass window for axion-photon couplings above $g_{\gamma} = 1.38\times g_{\gamma}^\text{KSVZ}$, reporting exclusion at the 90% level.