New Primary Caesium Fountain Clock PTB-CSF2 contributes for the first time to Coordinated Universal Time (UTC)
After its development and completion, PTB's second fountain clock CSF2 has undergone a series of tests so as to obtain a well-founded estimation of its systematic uncertainty. Such an estimation is a significant precondition for being accepted in the circle of the primary caesium atomic clocks which are used for the steering of Coordinated Universal Time (UTC). After also the international Working Group on Primary Frequency Standards has approved of CSF2's admission to this circle, the results of the first CSF2 measurements of the scale unit "second" have now been published and taken into account in the calculation of UTC. - more -
First Bose-Einstein condensate with Calcium atoms
When a dilute gas is cooled close to absolute zero the motion of the gas particles have to be described by quantum mechanics: The particles start to behave as waves. If the de-Broglie wavelength reaches the mean inter particle distance, a phase transition to a new state can occur: Bosonic particles accumulate in the ground state of the system forming a Bose-Einstein condensate. Bose-Einstein condensates have been used in the past years for a variety of measurements of fundamental quantum mechanics as well as a model system for solid state physics and for quantum information. - more -
A stable microwave source for fountain clocks on the basis of laser light
In a new approach, a microwave source for fountain clocks has been developed which uses - instead of an oscillating quartz - a microwave oscillator which has been stabilized with the aid of a highly stable laser and an optical comb to such an extent that its noise characteristics become insignificant for fountain operation. This allowed PTB's fountain clock CSF1 to work for the first time in the so-called quantum projection noise limit. - more -
