Conference on Precision Electromagnetic Measurements 

About: Conference on Precision Electromagnetic Measurements is an academic conference. The conference publishes majorly in the area(s): Voltage & Laser. Over the lifetime, 5106 publications have been published by the conference receiving 22889 citations.

Josephson D/A converter with fundamental accuracy

Abstract: A binary sequence of series arrays of shunted Josephson junctions is used to make a 14-b D/A converter. With 13 bias lines, any step number in the range -8192 to +8192 -1.2 V to +1.2 V can be selected in the time required to stabilize the bias current (a few microseconds). The circuit is a fast accurate dc reference, and it makes possible the digital synthesis of ac waveforms whose amplitudes derive directly from the internationally accepted definition of the volt. >

Optical molasses

Abstract: Summary form only given, as follows. A three-dimensional configuration of counterpropagating laser beams tuned slightly below an atomic resonance frequency can provide strong 'viscous' damping of the atomic kinetic motion through the action of then photon momentum. This 'optical molasses', first observed in experiments at Bell Labs, not only cools the atoms to microkelvin temperatures, but also provides confinement and concentration as well. Experiments at NIST in Gaithersburg showed that the temperatures reached in optical molasses were much lower than believed possible on the basis of simple and widely accepted theoretical models. Groups at Stanford University and at Ecole Normale Superieure in Paris both confirmed these experiments and offered novel theoretical models to explain the low temperatures. These models have been qualitatively verified in further experiments at all three laboratories. Experiments with cesium atoms in optical molasses at the Ecole Normale laboratory have found temperatures as low as 5 mu K. It corresponds to an RMS velocity of less than 2 cm/s. Such slow atoms may have important applications in a variety of measurements, including atomic frequency standards where atomic motion is the major factor limiting performance. >

Wave model solution to the ground/power plane noise problem

Abstract: In this paper, we describe the development of a theoretical field-based or "wave" model which we are employing in an attempt to characterize the ground/power plane (e.g., the V/sub cc/ plane) structure of a printed wiring board (PWB) or multichip module (MCM). A brief development of the model is presented, followed by simulation results and insight into the noise phenomena. A test structure and electrical measurements are used to confirm the correctness and applicability of the model. >

A 303-MHz frequency standard based on trapped Be/sup +/ ions

Abstract: A 303-MHz hyperfine transition in the ground state of 9Be+ was used as a basis of a frequency standard. The ions were stored in a Penning ion trap. Linewidths as narrow as 900μHz were obtained. The frequency stability was measured to be better than 3 x 10-12τ-1/2. The inaccuracy in the second-order .Doppler shift was reduced to 5 parts in 1015 by laser cooling. An apparent pressure shift with an unexpectedly large value was discovered which limits the accuracy of the current experiment to approximately 1 part in 1013.

A new scheme for generating and measuring active, reactive, and apparent power at power frequencies with uncertainties of 2.5/spl times/10/sup -6/

Abstract: A new method for generating and measuring active, reactive, and apparent power at power frequencies has been devised. It makes use of digital signal synthesis and discrete Fourier transform (DFT) evaluation based on a single master clock. This results in a significant reduction of synchronizing errors and thus in an uncertainty of only 2.5/spl times/10/sup -6/ (k=1).