The Nano-Atomic-Clock

AccuBeat LTD. is developing an innovative miniature atomic rubidium standard based on the coherent-population-trapping (CPT) phenomena. This standard, named nano-atomic-clock (NAC) is designed for very small size (~10cc) and very low power consumption (360mW). The NAC implements an extremely small "physics package" with a volume of 1cc. Although small in size and power the NAC achieves very high performance in terms of frequency stability. The CPT phenomenon is achieved by using light that contains two wavelengths that differ by the hyperfine ground transition of the ⁸⁷Rb (6.84 GHz). The NAC compact size and the low power consumption are achieved by replacing the (power hungry) Rb lamp and a filter cell that are used in the current technology with a miniature low power laser diode (the VCSEL). In order to improve both the short and the long term stability, AccuBeat has implemented a multiple servo-loop sophisticated scheme.