The Quantum Beat
Second Edition

By F. G. Major

Throughout history, a measure of the level of technological development of a society has been the precision of the clocks it was able to build. In our time the astonishingly accurate Global Positioning System for example, allowing pin-point precision in positioning instantaneously over the entire globe, is possible because of the development of quantum-based atomic clocks.

This book offers a broad understanding of the physical principles underlying and unifying the description of clocks based on the oscillatory behavior of physical systems as they evolved from early mechanical clocks to the present day quantum-based atomic clocks. It is written for the serious non-specialist with some physics or engineering background; the quantum aspects are dealt with in a self-contained broad manner with a minimum of mathematical symbolism.

The selection and organization of material, far from being narrowly formal, range over diverse salient topics touching on many facets of time and time-keeping, including:

• The relativistic concept of time
• Time's direction and entropy
• The history of mechanical clocks
• Quartz crystal oscillators
• Optical frequency oscillators (lasers)
• Laser cooling of electrically confined ions

The emphasis, however, is on the microwave and optical atomic frequency/time standards:

• The rubidium, cesium, hydrogen maser, and mercury ion- based clocks operating at microwave frequencies
• The laser-cooled cesium "atomic fountain" standard.
• The most recent single cold ion microwave and optical frequency standards.
• The measurement of optical frequencies
• Applications to navigation: Loran-C, GPS.