Bandi Nagabhushan, Thejesh

2016-6-1, Gharavipour, Mohammadreza, Affolderbach, Christoph, Kang, Songbai, Pellaton, Matthieu, Mileti, Gaetano, Bandi Nagabhushan, Thejesh, Gruet, Florian

We report our investigations on a compact high-performance rubidium (Rb) vapour-cell clock based on microwave-optical double-resonance (DR). These studies are done in both DR continuous-wave (CW) and Ramsey schemes using the same Physics Package (PP), with the same Rb vapour cell and a magnetron-type cavity with only 45 cm3 external volume. In the CW-DR scheme, we demonstrate a DR signal with a contrast of 26% and a linewidth of 334 Hz; in Ramsey-DR mode Ramsey signals with higher contrast up to 35% and a linewidth of 160 Hz have been demonstrated. Short-term stabilities of 1.4×10-13 τ-1/2 and 2.4×10-13 τ-1/2 are measured for CW-DR and Ramsey-DR schemes, respectively. In the Ramsey-DR operation, thanks to the separation of light and microwave interactions in time, the light-shift effect has been suppressed which allows improving the long-term clock stability as compared to CW-DR operation. Implementations in miniature atomic clocks are considered.

2015-10-27, Gharavipour, Mohammadreza, Affolderbach, Christoph, Kang, Songbai, Bandi Nagabhushan, Thejesh, Gruet, Florian, Pellaton, Matthieu, Mileti, Gaetano

We report our investigations on a compact high-performance rubidium (Rb) vapour-cell clock based on microwave-optical double-resonance (DR). These studies are done in both DR continuous-wave (CW) and Ramsey schemes using the same Physics Package (PP), with the same Rb vapour cell and a magnetron-type cavity with only 45 cm3 external volume. In the CW-DR scheme, we demonstrate a DR signal with a contrast of 26% and a linewidth of 334 Hz; in Ramsey-DR mode Ramsey signals with higher contrast up to 35% and a linewidth of 160 Hz have been demonstrated. Short-term stabilities of 1.4×10^-13 τ^-1/2 and 2.4×10^-13 τ^-1/2 are measured for CW-DR and Ramsey-DR schemes, respectively. In the Ramsey-DR operation, thanks to the separation of light and microwave interactions in time, the light-shift effect has been suppressed which allows improving the long-term clock stability as compared to CW-DR operation. Implementations in miniature atomic clocks are considered.

, Stefanucci, Camillo, Bandi Nagabhushan, Thejesh, Merli, Francesco, Pellaton, Matthieu, Affolderbach, Christoph, Mileti, Gaetano, Skrivervik, Anja K.

The design, realization, and characterization of a compact magnetron-type microwave cavity operating with a TE₀₁₁-like mode are presented. The resonator works at the rubidium hyperfine ground-state frequency (i.e., 6.835 GHz) by accommodating a glass cell of 25 mm diameter containing rubidium vapor. Its design analysis demonstrates the limitation of the loop-gap resonator lumped model when targeting such a large cell, thus numerical optimization was done to obtain the required performances. Microwave characterization of the realized prototype confirmed the expected working behavior. Double-resonance and Zeeman spectroscopy performed with this cavity indicated an excellent microwave magnetic field homogeneity: the performance validation of the cavity was done by achieving an excellent short-term clock stability as low as 2.4 × 10⁻¹³τ^−1/2. The achieved experimental results and the compact design make this resonator suitable for applications in portable atomic high-performance frequency standards for both terrestrial and space applications.