A quantum-enhanced search for dark matter axions

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.