The NIST program on chip-scale atomic clocks (CSAC) seeks to design, build and characterize miniature atomic frequency references based on fabrication techniques traditionally used in the field of microelectronics and microelectromechanical systems (MEMS). We are currently building structures (such as those shown above) that are the size of a grain of rice (V < 10 mm3) and could run on a AA battery (dissipate less than 75 mW). These atomic clocks are stable enough that they neither gain nor lose more than ten millionths of a second over the course of one day, and are paving the way for atomic-level timekeeping in portable, battery-operated systems such as global positioning receivers and wireless communication devices.

The Physics of Coherent Population Trapping

   1. Coherent population trapping (CPT)

   2. Atomic clocks based on CPT

   3. High-contrast CPT resonances

   4. Differential coherent population trapping

   5. Wall-coated alkali vapor cells

Chip-scale atomic clocks:

   1. Physics package fabrication

   2. Very early performance

   3. Electronics and local oscillator

   4. Applications

   5. Long term frequency stability of chip-scale atomic clocks

   6. Basic questions and answers

Advanced chip-scale atomic clocks:

   1. CSACs with improved short-term stability

   2. Atomic vapor cells with improved long-term stability

   3. Long-term frequency stability of chip-scale atomic clocks

Selected publications:

S. Knappe, L. Liew, V. Shah, P. Schwindt, J. Moreland, L. Hollberg and J. Kitching, "A microfabricated atomic clock," Appl. Phys. Lett., 85, 1460, 2004.

1. S. Knappe, Emerging Topics: MEMS atomic clocks, in Y. Gianchandani, O. Tabata, and H. Zappe, (eds.) Comprehensive Microsystems, 2007, Elsevier, Netherlands.
   

Acknowledgements:

This work was carried out in collaboration with the Electromagnetic Technology Division with funding from NIST and the Microsystems Technology Office at the Defense Advanced Research Projects Agency (DARPA).