Mclocks: High-performance microwave clocks for industrial applications

Key members

In the Mclocks project LTF collaborates with a European consortium aiming to transfer recent advances in laboratory compact microwave atomic clocks towards new atomic clock instruments suitable for demanding industrial and technical applications in terms of frequency stability, size, power consumption and reliability. These new clocks shall show outstanding stability performances, i.e. fractional frequency stabilities (Allan deviation) of 10-13 at 1s and in 10-15 range at one day time scale.

Pulsed optically pumped (POP) Rubidium (Rb) vapour cell frequency standard

The use of optical-microwave double-resonance spectroscopy by the time-domain Ramsey interrogation technique has been shown to be an efficient approach for the realisation of vapour-cell microwave atomic clocks with state-of-the art frequency stability [2]. This pulsed optically pumped (POP) interrogation scheme allows detection of high-contrast, narrow-linewidth, and high signal-to-noise signals from a small (cm-size) thermal Rb vapour cell, as well as very small light-shift effects, which is very beneficial for the realization of the envisaged clock.
In this project we investigate using a very compact (45 cm3) magnetron-type microwave cavity for microwave interrogation of the atomic sample [3]. This magnetron cavity has a three times smaller size than conventional fundamental-mode cavities and thus enables the realization of very compact POP clocks. A compact and frequency-stabilized laser head with switchable output laser power is under development in our group for this clock. This laser head and the new clock physics package based on the magnetron microwave cavity will be combined to form the core of a very compact and high-performance POP clock of high interest for future industrial or portable applications. The POP clock development is conducted in collaboration with the Istituto Nazionale di Ricerca Metrologica (INRIM).


Narrow and high-contrast Ramsey fringes observed in POP clock mode, using the compact magnetron microwave cavity [1].


Core of the compact magnetron microwave cavity developed by UniNe-LTF and EPFL-LEMA [3].

Other developments within the Mclocks project

Our team also contributes to the development of two other clock types addressed within the Mclocks project: Spectroscopic evaluation of Cs vapour cells using Coherent Population Trapping (CPT) is conducted in view of a Cs-cell CPT atomic clock, in collaboration with Observatoire de Paris / SYRTE and Université de Franche-Comté / FEMTO. In collaboration with Observatoire de Paris / SYRTE, a special spherical microwave cavity is studied. This microwave cavity is foreseen for use in a Rb cold atom pulsed microwave atomic clock (Rubiclock).

The Mclocks project is funded by the European Metrology Research Programme (EMRP, project IND55). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.

Relevant publications

  1. S. Kang, M. Gharavipour, C. Affolderbach, G. Mileti, Stability limitations from optical detection in Ramsey-type vapour-cell atomic clocksElectronics Letters 51 (22), 1767-1769 (2015). PDF

  2. C. Affolderbach, G.-X. Du, T. Bandi, A. Horsley, P. Treutlein, G. Mileti, Imaging Microwave and DC Magnetic Fields in a Vapor-Cell Rb Atomic Clock, IEEE Transactions on Instrumentation and Measurement 64 (12), 3629-3637 (2015). PDF

  3. S. Kang, M. Gharavipour, C. Affolderbach, F. Gruet, G. Mileti, Demonstration of a high-performance pulsed optically pumped Rb clock based on a compact magnetron-type microwave cavity, Journal of Applied Physics 117, 104510 (2015). PDF

  4. S. Kang, C. Affolderbach, F. Gruet, M. Gharavipour, C. E. Calosso, G. Mileti, “Pulsed optical pumping in a Rb vapour cell using a compact magnetron-trype microwave cavity”, Proceedings of 28th European Frequency and Time Forum (EFTF), Neuchâtel, Switzerland, (2014). Php 

  5. S. Micalizio, A. Godone, C. Calosso, F. Levi, C. Affolderbach, F. Gruet, “Pulsed optically pumped Rubidium clock with high frequency stability performance”, IEEE Trans. Ultrason., Ferroelectr., Freq. Control. Vol. 59, No. 3, pp. 457-462 (2012). PDF
  6. C. Stefanucci, T. Bandi, F. Merli, M. Pellaton, C. Affolderbach, G. Mileti, A. K. Skrivervik, “Compact microwave cavity for high performance rubidium frequency standards”. Rev. Sci. Instrum. 83, 104706 (2012). PDF