讲座题目：Observation of a Periodic Many-body System
报 告 人：Prof. Klaus Müller-Dethlefs
Founding Director of the Photon Science Institute, University of Manchester
The path from Structure and Phase to Quantum Entanglement is of considerable interest since the latter is viewed as an important route towards quantum computing, for instance, by invoking the concept of q-bits produced from entanglement of two particles. For many-body systems the concept of quantum entanglement is still in its infancy. Starting from the common textbook opinion that in many-electron atoms the electrons are entangled (a deeper reason for the periodic system of the elements), one can speculate that periodicity should play an important role in much larger systems.
Here, we report the experimental observation of a very striking periodicity in a many-body system--an ultra-cold plasma. A long life-time (>0.3ms) quantum degenerate molecular Rydberg plasma is generated in the high-density region of a pulsed supersonic jet expansion by two-colour resonant excitation of nitric oxide (10%) in neon (5bar) into the high-n Rydberg threshold region close to the ionization limit. For plasma densities of >1016cm–3reached in our experiments the electrons should become quantum degenerate, i.e. the electron de Broglie wavelength becomes larger than the Wigner-Seitz radius a relevant to describe the mean distance between the particles.
When analysing the plasma with pulsed electric fields, we observe very sharp, periodic peaks in the time-of-flight spectrum. These sharp resonances follow a totally reproducible progression of mass-to-charge, i.e. ion-to-electron ratios, and originate from a plasma ion crystal of macroscopic size embedded in ultra-cold electrons. The observation of such many-body states with periodic ion/electron ratios suggests a phase correlation and possibly quantum entanglement.
Chaired Professor Klaus Müller-Dethlefs obtained his Ph.D degree in 1979 at Department of Chemical Engineering and Technology, Imperial College, University of London. In 1985 he became the Professeur invité at the Université de Bourgogne, Dijon, France. He was the pre-Director of The Photon Science Institute, Chair of Physics and Chair of Chemistry, at the University of Manchester. He was a visiting Professor in many world leading institutions. In 2004, he was elected the Fellow of The Institute of Physics. He was also the Chairman or Co-Chair of many world famous conferences, such as the Gordon Research Conference. He won the Rudolf-Kaiser-Preis in 1994, the Herzberg Memorial Prize in 2001, and the Miller Award in 2007. Prof. Klaus published more than hundred fifty publications in top international journals, over three hundred invited and plenary lectures at international scientific conferences, including many Gordon Research Conferences, and more than two hundred invited seminars at scientific institutions all over the world.