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

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 × 10 −11 rad/ √ 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.