Miniature Atomic Clocks

Atomic clocks are oscillators providing a signal with exquisite frequency (and hence timing) stability, derived from ultra-stable alkali atomic transitions in a controlled environment. A miniature atomic clock (MAC) combines the advantages of reduced size, weight and power (SWaP) with superior timing accuracy over quartz-based technologies. MACs have the potential to improve the performance of secure telecommunication systems or Global Navigation Satellite System (GNSS) instruments. In macQsimal, we join forces to cover and master the whole atomic clock development chain, from physics understanding and requirements assessment, through design and prototyping, manufacturing and tests, up to product qualification and commercialization.

Objective: in macQsimal, partners work closely together to develop a Miniature Atomic Clock (MAC) prototype based on coherent population trapping (CPT) in 87Rb filled MEMS atomic vapor cells, with very low SWaP and costs and with exquisite long-term performances. 

Related macQsimal publication

Long-Term Stability Analysis Toward <10-14 Level for a Highly Compact POP Rb Cell Atomic Clock Almat, N., Gharavipour, M., Moreno, W., Gruet, F., Affolderbach, C., Mileti, G. (2019) IEEE Transactions on Ultrasonics, Ferroelectronics, and Frequency Control (TUFFC), 67(1), 207-216.

Vapor cells for atomic clocks

The technique used in macQsimal for the production of vapor cells is identical to the technique used in the production of integrated electronic circuits. Hence, we can produce a large number of vapor cells at once compiled in a 150mm diameter wafer. Individual vapor cells for the atomic clock have a typical size of 4 by 4mm. More than 700 units fit on a single wafer. The silicon cell core contains a cavity that is closed on both sides with a glass lid. MEMS atomic vapor cells for MAC application consist (RbN3) followed by UV decomposition.
Fully assembled 150mm wafer stack with 704 vapor cells designed for application in miniaturized atomic clocks (MAC).

Miniaturized atomic clock (MAC)

The physics package is a key element of a MAC: it provides all the interactions tools between the clock control electronics and the atoms. The essential step in the development of MAC is the hermetic encapsulation of the physics package (PP).

CSEM recently patented a low-cost ultra-flat miniature atomic clocks physics package that combines the advantages of reduced size, weight, and power, with superior timing accuracy over high-end quartz-based technology.

Enhancement of miniturized atomic clocks

Within macQsimal we investigate the reduction of fundamental clock instabilities for improved miniature atomic clock performance. For this purpose, our partners from UNINE study how advanced quantum interrogation techniques similar to those currently used in the much bigger primary atomic clocks can be employed to miniaturized cells. Once these techniques are implemented in the clock, we can measure the obtained clock stability and thus assess the gain in performance.

Towards market applicability

Our objective within the macQsimal project is to further reduce the size and power consumption of a new prototype miniature atomic clock (MAC). The strong collaboration between research and industry provides an excellent platform to push the MAC close to market maturity. CSEM and VTT provide state-of-the-art micro-fabrication technology including cleanroom facilities and expertise in MEMS manufacturing, assembly, and packaging. Then at the system level, Orolia integrates the micro-fabricated system with electronics and software. Developed clocks can provide stable time- and frequency signals for applications such as network synchronisation, mobile communication, radar, and satellite navigation.

Application of the MACs for the satellite navigation.