Microwave Phase Detection at the Level of $10^{-11}$ rad

TL;DR

This paper introduces a highly sensitive microwave phase detection system with unprecedented spectral resolution, enabling detailed analysis of phase fluctuations and revealing a new phenomenon of phase noise down-conversion.

Contribution

The paper presents the development of a microwave noise measurement system with the highest spectral resolution, capable of detecting extremely small phase fluctuations and uncovering a new phase noise down-conversion phenomenon.

Findings

Detected phase fluctuations as low as 2×10^{-11} rad/√Hz

Discovered down-conversion of pump oscillator phase noise into low-frequency voltage fluctuations

Enabled studies of intrinsic fluctuations in microwave components and materials

Abstract

We report on a noise measurement system with the highest spectral resolution ever achieved in the microwave domain. It is capable of detecting the phase fluctuations of $rms$ amplitude of $2\times10^{-11} rad/\sqrt{Hz}$ at Fourier frequencies above few $kHz$. Such precision allows the study of intrinsic fluctuations in various microwave components and materials, as well as precise tests of fundamental physics. Employing this system we discovered a previously unknown phenomenon of down-conversion of pump oscillator phase noise into the low-frequency voltage fluctuations.