Orateur
Description
Basics on Quantum Noise and Squeezing
Serge Reynaud
Directeur de recherche émérite au CNRS
Laboratoire Kastler Brossel (Paris)
(Sorbonne Université, ENS-PSL, Collège de France, CNRS)
Quantum noise arises from the basic principles of quantum theory. It is a limitation in all high-sensitivity measurements, when other sources of noise are mastered.
When the quantum noise level is attained, there still exist ways to reduce the impact of quantum noise on sensitivity by “squeezing” its effect on the observable of interest.
Gravitational wave detection has always been a deeply rooted motivation for developing ideas and techniques to attain the quantum noise level and go beyond it if possible.
Today, GW detection is an amazing application of squeezing with an eminent place among the many applications proposed along the years.
As for many quantum phenomena, there are different manners of discussing qualitatively the origin and effects of quantum noise and squeezing.
First, a laser beam is a flow of photons. Shot noise is due to the statistics of photon counting and it is the simplest way to understand quantum noise in intensity measurements.
Then, a deeper understanding requires to describe quantum fluctuations of the various field observables involved in a more general measurement.
In the talk, I give a simple presentation of this understanding and discuss the principles of its application to the domain of gravitational wave detection with optical interferometers.
