Related Experiment Video
Updated: Aug 9, 2026

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Quantum theory of light and noise polarization in nonlinear optics
Stefan Scheel1, Dirk-Gunnar Welsch
1Quantum Optics and Laser Science, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW, UK. s.scheel@imperial.ac.uk
Abstract:
We present a consistent quantum theory of the electromagnetic field in nonlinearly responding causal media, with special emphasis on Chi(2) media. Starting from QED in linearly responding causal media, we develop a method to construct the cubic Hamiltonian expressed in terms of the complex nonlinear susceptibility in a quantum mechanically consistent way. In particular, we show that the method yields the nonlinear noise polarization, which together with the linear one is responsible for intrinsic quantum decoherence.
Related Concept Videos
The Wave Nature of Light
The de Broglie Wavelength
Potential Due to a Polarized Object
Interference and Diffraction
Emission Spectra
The Quantum-Mechanical Model of an Atom

