A History of the Rubidium Frequency Standard

This paper is a history of the rubidium gas cell atomic frequency standard, by far the most widely deployed type of atomic clock. Since the early 1960’s, rubidium frequency standards (RFS) have offered an attractive combination of practicality and performance that spans a range of applications from low-cost commercial devices for telecommunications timing, ruggedized tactical units for military use, and high stability, high reliability space clocks for global navigation systems. The paper describes their physical basis, the early scientific work that created them, and their subsequent product development and widespread commercialization from the perspective of an early contributor to this field. It emphasizes the author’s experiences at several organizations that continue to make RFS devices, and similar new atomic clock technology, smaller, better, and cheaper. That work was carried out in the U.S. and elsewhere by a series of organizations and people following several distinct timelines and heritages. The first complete RFS was designed in the late 1950’s at ITT in Nutley, NJ by Dr. Maurice Arditi with Dr. Thomas Carver of Princeton, and that organization is now the largest user of space Rb clocks for their GPS navigation payloads. The first commercial RFS appeared in the early 1960’s from General Technology and Space Technology Laboratories. Some of the first commercial RFS were built circa 1962 by Varian Associates in Palo Alto, CA, and that technological legacy continues today.