Colloquium: Bertrand Reulet

What are the properties of the electromagnetic field radiated by a quantum conductor, or how to generate entangled radiation with a normal metal ?

Bertrand Reulet, University of Sherbrooke

​A classical current in a conductor radiates a classical electromagnetic field. We explore some properties of the field radiated by a conductor when electron transport must be described by quantum mechanics, i.e. when the electron current becomes quantum itself. Using a tunnel junction between normal metal contacts placed at ultra-low temperature as a quantum conductor, we demonstrate the existence of squeezing as well as entanglement in the microwave radiation, thus proving that the electron shot noise generates a quantum electromagnetic field. We discuss the origin of these quantum features in terms of correlations in the electron current in the junction.