4137 / Amperage (Ampere): SET-Chip and Kryostat at the PTB in Braunschweig: EUROPA, DEUTSCHLAND, NIEDERSACHSEN, BRAUNSCHWEIG (BRAUNSCHWEIG, GERMANY), 29.06.2007: Realization of the ampere, SI base unit of current, at Physikalisch-Technische Bundesanstalt PTB in Braunschweig, Germany. In an attempt to redefine the ampere by tying it to a fundamental constant, the charge of an electron, PTB scientists have developed an SET chip - single-electron tunneling - which transports and counts single electrons. This quantum effect only occurs at low temperatures, therefore a cryostat - at right - cools the chip down to 20 mK. - Marc Steinmetz / VISUM - Keywords: Germany, Physikalisch, Technische, Bundesanstalt, PTB, science, technology, physics, metrology, base, unit, international, system, of, units, SI, metrical, measure, measurement, standard, accurate, accuracy, lab, ampere, current, electricity, SET, chip, single, electron, tunneling, cryostat, quant