The Mysteries and Surprises of Quantum Physics

Manipulating and controlling single photons interacting in a cavity can shed some light on fundamental aspects of quantum physics.

This is exactly what a sub-field of quantum optics called "cavity quantum electrodynamics" is trying to do, in an experiment made by professor Serge Haroche from the Coll�ge de France and the �cole Normale Sup�rieure in Paris, along with his colleagues.

They are trying to study the behavior of these photons in a protected environment, in fact a box made of highly reflecting walls, which doesn't destroy photons, allowing the scientists to study them for much longer periods than ever before.

Extracting quantum information attempts to harness the logic of the quantum world to perform tasks in communication and computing that classical devices cannot achieve.

"During the 20th century, quantum physics has given us new technologies that have changed our lives - for example the computer, the laser and magnetic resonance imaging to name a few," explained Prof. Haroche. "However, quantum laws have counterintuitive aspects that defy common sense. This has led to a paradox: although we all take advantage of quantum physics, it remains very strange - even some of the scientists that developed the theory, such as Einstein, Schr�dinger and de Broglie, were uneasy about its deep meaning," he said.

The approach of manipulating and controlling quantum systems in experimental applications raises significant questions concerning the transition between quantum and classical behavior.

"Fundamentally, the goal is to understand nature better," explained Prof. Haroche. "Applications, such as quantum communication machines, will certainly come but what they will be useful for is not yet clear. This is why research is so exciting - unpredictable things keep happening all the time."

They hope their work will help better understand some phenomena exhibited by quantum systems, like decoherence, complementarity and state superpositions.