frequency standards; microwave cavities; vapor cells; atomic clocks; field homogeneity
Almat Nil, Moreno William, Pellaton Matthieu, Gruet Florian, Affolderbach Christoph, Mileti Gaetano (2018), Characterization of Frequency-Doubled 1.5- $\mu$ m Lasers for High-Performance Rb Clocks, in
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 65(6), 919-926.
Almat Nil, Pellaton Matthieu, Moreno William, Gruet Florian, Affolderbach Christoph, Mileti Gaetano (2018), Rb vapor-cell clock demonstration with a frequency-doubled telecom laser, in
Applied Optics, 57(16), 4707-4713.
Pellaton M, Affolderbach Christoph, Skrivervik Anja K., Ivanov Anton E., Debogovic T., Rijk E. de, Mileti Gaetano (2018), 3D printed microwave cavity for atomic clock applications: proof of concept, in
Electronics Letters, 54(11), 691-693.
Affolderbach Christoph, Moreno W., Ivanov Anton E., Debogovic T., Pellaton M, Skrivervik Anja K., Rijk E. de, Mileti Gaetano (2018), Study of additive manufactured microwave cavities for pulsed optically pumped atomic clock applications, in
Applied Physics Letters, 112(11), 113502.
Gharavipour Mohammadreza, Affolderbach Christoph, Gruet Florian, Mileti Gaetano, Radojicic Ivan S., Krmpot Aleksandar J., Jelenkovic Brana M. (2017), Impact of static-magnetic-field-gradients on relaxation times in a Rb vapor cell, in
2017 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Cont, 57-59.
Gharavipour M, Affolderbach C, Gruet F, Radojičić I S, Krmpot A J, Jelenković B M, Mileti G (2017), Optically-detected spin-echo method for relaxation times measurements in a Rb atomic vapor, in
New Journal of Physics, 19(6), 063027-063027.
Ivanov Anton E., Affolderbach Christoph, Mileti Gaetano, Skrivervik Anja K. (2017), Design of atomic clock cavity based on a loop-gap geometry and modified boundary conditions, in
International Journal Of Microwave And Wireless Technologies, 9(7), 1373-1386.
Ivanov A. E., Skrivervik A. K., Affolderbach C., Mileti G. (2016), Compact microwave cavity with increased magnetic field homogeneity, in
2016 10th European Conference on Antennas and Propagation (EuCAP), Davos1-5, EurAAP, Davos1-5.
Ivanov A. E., Affolderbach C., Mileti G., Skrivervik A. K. (2016), Study of field misalignment in a cavity used for atomic clock applications, in
2016 URSI International Symposium on Electromagnetic Theory (EMTS), Helsinki308-311, URSI, Helsinki308-311.
This research proposal concerns the study of novel types of microwave cavities, for applications in compact and high-performance vapor-cell atomic clocks, and more particularly in such atomic clocks operated in the pulsed optically pumped scheme. Such compact vapor-cell atomic clocks (volumes < 5 liters) are the instruments of choice in many of today’s key applications where excellent timing and frequency stability on the level of = 1 ns/day (relative frequency stability = 1x10^-14/day) are required from a small and mobile system. In both continuous-wave (cw) and pulsed double-resonance (DR) vapor-cell atomic clocks, precise control of the microwave field distribution across the atomic sample held in the vapor cell is required, in order to achieve a strong atomic signal with high quality factor, and thus state-of-the-art short-term clock stability. Generally, a microwave cavity resonator is used for this purpose in a vapor-cell clock. Similarly, imperfections in the directivity and homogeneity of the applied microwave field can result in position-dependent systematic effects (e.g. such as microwave power shifts) that can degrade the long-term clock stability. The control and optimization of the microwave field distribution in the cavity resonator used is thus critical for assuring the best possible stability performance of a vapor-cell clock. In the pulsed optically pumped (POP) approach, the homogeneity of the microwave field amplitude over the entire atomic sample is of strongly increased importance, because all atoms should undergo near-perfect pi/2-pulses to take full advantage of this clock scheme. In existing present studies this is achieved by making the atomic vapor cell occupy only a small fraction of the microwave cavity, making the overall clock package rather bulky. It is thus of interest to achieve a close to ideal field distribution from a cavity as small as possible, in order to keep the overall clocks small and of interest for distributed and/or mobile applications. In previous work of the applicants, novel microwave cavities based on the loop-gap resonator approach (LGR, also known as magnetron-type resonator) have been developed and studied, including their applications in cw DR atomic clocks. In this present project proposal, we will extend this work to also study specifically novel microwave cavities based on the same LGR approach, but optimized for clock operation in the POP clock scheme. The project goal is thus to develop and study a novel microwave cavity for a POP clock, with close to ideal field distribution and as small size as possible, and to experimentally evaluate the impact of such cavities on the atomic clock performance. For this purpose we propose a collaborative research approach, in which EPFL-LEMA contributes its expertise in microwave system design, prototyping, studies, and characterization, and UniNe-LTF contributes its expertise in atomic spectroscopy, atomic clock physics, and metrology. In a first project step, a theoretical model will be developed in order to allow making clock performance predictions for a given microwave field distribution in the cavity. In a second step, this model will then be used to develop a new, highly compact, and optimized LGR cavity for the POP clock, including a new tuning scheme for the resonance frequency. The model will also be validated experimentally by experimental clock studies with existing microwave resonators. Finally, a prototype of the new optimized LGR cavity will be realized and studied.