People > Daniel Kleppner > Biographical Background

Biographical Background

Professor Daniel Kleppner is a principal investigator in the Research Laboratory of Electronics (RLE) at the Massachusetts Institute of Technology (MIT). He has made fundamental contributions to atomic physics and quantum optics, mainly using hydrogen and hydrogen-like atoms. He built new devices, performed spectroscopic tests of extreme precision and investigated novel quantum phenomena. From 1987 to 2000, he was Associate Director of RLE. From 2001 to 2001, he was Interim Director of RLE.

In 1960, along with Norman Ramsey, he developed the Hydrogen maser, later used as an atomic clock of unprecedented stability. Applications of this early work range from coordination of radiosignals in long base-line radio astronomy, to satellite-based global positioning systems.

In the 1970's Professor Kleppner was a pioneer in the physics of Rydberg atoms. These very excited atoms have a wide range of remarkable properties. His proposal and demonstration of the inhibition of spontaneous emission from Rydberg atoms was an early step in Cavity Quantum Electrodynamics, concerned with the radiative properties of atoms in confined spaces. Kleppner's investigations of Rydberg atom spectra in high electric and magnetic fields provided deep physical insight into the implications of classical chaos for quantum systems.

Professor Kleppner and RLE colleague Professor Thomas Greytak were among the first to look for quantum degeneracy effects in ultra-cold gases. After a 20-year long quest, in 1998, they achieved Bose-Einstein condensation (BEC) in hydrogen. In the meanwhile, they developed tools instrumental to the 1995 discovery, by RLE alumni Eric Cornell and Carl Weiman, and RLE's Wolfgang Ketterle, of BEC in alkali atoms. These include the technique of evaporative cooling, demonstrated in collaboration with HaraldHess. In their tour de force hydrogen BEC work, Professor Kleppner and his colleagues pioneered a whole new field of physics. Bose-Einstein condensates and fermionic degenerate samples of cold atoms, currently created under various forms in many laboratories around the world, represent a new form of matter at the lowest temperatures ever achieved. Their study opens fascinating perspectives for applications in both fundamental and applied research.

In addition to these research achievements, Professor Kleppner has been a dedicated teacher, advising many Ph.D. students who have gone on to attain prestigious positions in major universities. Some of these students have received the highest scientific awards for their own work, including a Nobel Prize (RLE alumni William Phillips, 1997). Professor Kleppner has also served on numerous national committees charged with investigating key scientific or social issues.