4137 / Time (Seconds): optical Atomic clock at the PTB in Braunschweig: EUROPA, DEUTSCHLAND, NIEDERSACHSEN, BRAUNSCHWEIG (BRAUNSCHWEIG, GERMANY), 16.04.2007: Prototype optical atomic clock in a quantum optics laboratory at Physikalisch-Technische Bundesanstalt PTB in Braunschweig, Germany. The device is at least 100x as accurate as existing ceasium atomic clocks and may one day serve as a better primary standard of frequency. In a magneto-optical trap inside the spherical vacuum chamber, magnetic coils and six laser beams trap and cool 10 million strontium atoms - blue dot at center of porthole - which are then stimulated to a selected atomic transition of a specific frequency by a seventh beam. This oscillation is a pacemaker of unrivalled accuracy. - Marc Steinmetz / VISUM - Keywords: time, base, unit, international, system, of, units, measurement, caesium, atomic, clock, clocks, frequency, standard, science, technology, lab, quantum, optics, laser, accuracy, physics, metrology