Focus on Microlaser and Cavity QED

Abstract

Light has always been the most important carrier of information. Most of the information received by a human is visual. Technological breakthroughs have been made by changing from copper networks to networks based on optical data processing using laser light. In the last fifteen years, however, research has gone much further. We can now generate and control new sources of nonclassical light which are constructed from single atoms in a resonator. The systems for generating this new light are the micromaser in the microwave regime and the microlaser in the optical regime. Fundamental properties as well as possible applications have been investigated in a common European effort within the TMR network Microlasers and Cavity QED. Funded by the European Commission seventeen teams have been working together sharing their knowledge about the fundamental interaction of light with matter. These Focus articles will highlight several important findings of this collaboration.From the selection of papers one can immediately see the wide range of research that has been done in this European project. New quantum effects have been found in the interaction of a single light mode with single atoms and new properties of the corresponding field states have been explored. The fundamental forces acting on atoms in a cavity field have been simulated. This will open new ways to cool an ensemble of atoms in a cavity. In addition it has been shown that cold atoms can be transported in a waveguide. Regarding semiconductor microlasers the quantum noise of vertical surface emitting lasers (VCSELs) has been understood experimentally as well as theoretically.The focus articles also demonstrate that the ability to manipulate quantum characteristics of light will have direct applications in information technology. Systems based on cavity QED are candidates for future processing of quantum information. One of the most challenging tasks therefore is to understand the dissipative effects and to actively control the decay of atomic states. A clear understanding of all these decoherence effects then allows for the development of error avoiding quantum codes that stabilize quantum algorithms within the realm of cavity QED.At this point we take the opportunity to thank the authors and the reviewers of these articles for preparing and ensuring high-quality presentations. We are convinced that this cluster of articles will give the readers a broad insight into an inspiring piece of modern physics.Focus on Microlaser and Cavity QED ContentsCoherent states sometimes look like squeezed statesand vice versa: the Paul trap Michael Martin Nieto and D Rodney TruaxError avoiding quantum codes and dynamical stabilization of Grover's algorithm Michael Mussinger, Aldo Delgado and Gernot AlberSchrödinger-cat entangled state reconstruction in the Penning trap Michol Massini, Mauro Fortunato, Stefano Mancini,Paolo Tombesi and David VitaliNonlocality of the Schrödingercat Krzysztof WódkiewiczDriving atoms into decoherence-free states Almut Beige, Daniel Braun and Peter L KnightTransport of cold atoms in a miniature guide M Key, W Rooijakkers and E A HindsQuantum noise in VCSELs J-P Hermier, I Maurin, E Giacobino, P Schnitzer, R Michalzik,K J Ebeling, A Bramati and A Z KhouryA physical explanation of excess quantum noise due to non-orthogonal modes A M van der Lee, M P van Exter, N J van Druten and J P WoerdmanCollective light forces on atoms in a high-finesse cavity T Fischer, P Maunz, T Puppe, P W H Pinkse and G RempeTunable whispering gallery modes for spectroscopy and CQED experiments Wolf von Klitzing,Romain Long, Vladimir S Ilchenko, Jean Hareand Valérie Lefèvre-Seguin Matthias Freyberger and Wolfgang Schleich Abteilung für Quantenphysik, Universität Ulm, Germany