LTC Research

The aim of the Theoretical Centre for Quantum System Research is to explore and merge ideas and methods of three prominent research directions in modern atomic, molecular and optical physics.

Atomic physics with new light sources (Poster): The general field of laser-matter interactions is characterized by impressive progress in laser technology as well as cooling and trapping techniques. Light sources with pulses of shorter and shorter duration and ever increasing intensities are being developed, and pulses containing only a few cycles and with a duration of less than 10 femtoseconds (1 fs = 10-15 s) are now commercially available. Intensities of 1014 W/cm2 are routinely provided, and intensities two orders of magnitude higher, reaching the field strength of the Coulomb interaction in atoms and molecules, are not unusual. Femtosecond laser pulses have been used to produce coherent extreme-ultraviolet pulses of attosecond duration (1 attosecond = 10-18 s), and the expression “attosecond metrology” was coined for the investigation of matter with such short pulses. Femtosecond pulses led to the development of femtochemistry with studies of chemical reactions in real time. The even shorter pulses will allow attosecond spectroscopy of bound electrons, and we are only beginning to apprehend what new science will evolve from attosecond research. Control of the pulse shape (envelope), bandwidth and, most recently, carrier phase are major factors of practical value in studying time-dependent ultrafast processes that arise in physics, electronic engineering, chemistry and in many areas of the life sciences.

Cold atoms and matter waves (Poster): Cold atoms and matter waves started as a research field in the 1980’s. It addresses the external motion of the atoms and has progressively led to cooling of atoms to lower and lower temperatures, reaching today the vicinity of a nanoKelvin (10-9 K) above absolute zero. Such ultra-cold atomic ensembles are interesting on the single particle level as they facilitate precision spectroscopy and careful studies of the interactions. On a many-particle level the manifestation of collective quantum effects in ultra-cold gases represents an intriguing avenue for exploring phenomena in condensed matter physics. When bosonic atoms are cooled, a large fraction of them condense and pile up into a single, coherent matter wave state, a so-called Bose-Einstein condensate (BEC). The first BECs were produced in laboratories in 1995, and today there are about 50 BEC experiments worldwide and three independent experimental activities in Denmark. The internal electronic structure of the atoms make many-atom systems easy to detect and control by laser and magnetic fields, and they offer completely new possibilities, such as “super-chemistry”, where the atoms bind to form molecules in a coherent fashion.

Quantum optics and information (Poster): Quantum Optics deals with the dynamics of single quantum systems manipulated and observed by their emission and absorption of light. Early studies focussed on the observation and characterization of genuine non-classical behaviour, which could both serve to illuminate the special character of quantum theory and which could be used for applications because special quantum light could be made less noisy than allowed classically. Special quantum states of light and single atoms can be used to code information, and such quantum information provides revolutionary means for secure communication and fast computing. When light interacts with large atomic ensembles, the total number of atoms populating different electronic states is, surprisingly, a very robust quantum degree of freedom. The detection of the light provides means for detection and manipulation of the collective atomic states of relevance for quantum storage, squeezing and entanglement, quantum state teleportation, and precision metrology.

Comments on content to: Grete Flarup
Revised 14.07.2009