Speeding axion haloscope experiments using heterodyne-variance-based detection with a power-meter

TL;DR

This paper introduces a novel axion detection technique that measures interference variance with a power meter, eliminating the need for linear amplifiers and enabling near-quantum-limited sensitivity.

Contribution

The paper presents a new heterodyne-variance-based detection method for axion searches that simplifies setup and improves sensitivity over traditional approaches.

Findings

Demonstrated the method with a simple circuit prototype.

Achieved sensitivity close to the quantum noise limit.

Validated the approach through analytical, numerical, and experimental results.

Abstract

We describe a new axion search method based on measuring the variance in the interference of the axion signal using injected photons with a power detector. The need for a linear amplifier is eliminated by putting a strong signal into the microwave cavity, to acquire not only the power excess but also measure the variance of the output power. The interference of the external photons with the axion to photon converted signal greatly enhances the variance at the particular axion frequency, providing evidence of its existence. This method has an advantage in that it can always obtain sensitivity near the quantum noise limit even for a power detector with high dark count rate. We describe the basic concept of this method both analytically and numerically, and we show experimental results using a simple demonstration circuit.