Measurements of the Correlation Function of a Microwave Frequency Single Photon Source

TL;DR

This paper demonstrates how to characterize microwave single photon sources using correlation measurements with linear amplifiers, overcoming the lack of efficient microwave photon counters, and also shows cavity cooling detection via cross-correlation.

Contribution

It introduces a method to analyze microwave single photon sources through correlation measurements with linear amplifiers, enabling characterization without single photon counters.

Findings

Successful measurement of microwave photon correlations

Detection of cavity cooling via cross-correlation

Advancement in microwave quantum optics techniques

Abstract

At optical frequencies the radiation produced by a source, such as a laser, a black body or a single photon source, is frequently characterized by analyzing the temporal correlations of emitted photons using single photon counters. At microwave frequencies, however, there are no efficient single photon counters yet. Instead, well developed linear amplifiers allow for efficient measurement of the amplitude of an electromagnetic field. Here, we demonstrate how the properties of a microwave single photon source can be characterized using correlation measurements of the emitted radiation with such detectors. We also demonstrate the cooling of a thermal field stored in a cavity, an effect which we detect using a cross-correlation measurement of the radiation emitted at the two ends of the cavity.