Planck Spectroscopy and the Quantum Noise of Microwave Beam Splitters

TL;DR

This paper uses microwave quantum optics techniques to analyze vacuum fluctuations and quantum noise in beam splitters, providing experimental evidence of fundamental quantum limits in microwave signal processing.

Contribution

It introduces a correlation function analysis method to characterize quantum noise and vacuum fluctuations in microwave beam splitters, advancing understanding of quantum noise limits.

Findings

Vacuum fluctuations depend on frequency as shown by Planck spectroscopy.

Quantum noise added by beam splitters is at the fundamental minimum.

Correlation analysis effectively characterizes quantum properties of microwave components.

Abstract

We use a correlation function analysis of the field quadratures to characterize both the black body radiation emitted by a 50 Ohm load resistor and the quantum properties of two types of beam splitters in the microwave regime. To this end, we first study vacuum fluctuations as a function of frequency in a Planck spectroscopy experiment and then measure the covariance matrix of weak thermal states. Our results provide direct experimental evidence that vacuum fluctuations represent the fundamental minimum quantum noise added by a beam splitter to any given input signal.