Gruet, Florian

2017-6-26, Gharavipour, Mohammadreza, Affolderbach, Christoph, Gruet, Florian, Mileti, Gaetano, Jelenkovic, Branislav, Radojicic, I.S, Krmpot, A.

Weintroduce and demonstrate an experimental method, optically-detected spin-echo (ODSE), to measure ground-state relaxation times of a rubidium (Rb) atomic vapor held in a glass cell with buffergas. The work is motivated by our studies on high-performance Rb atomic clocks, where both population and coherence relaxation times (T1 and T2, respectively) of the ‘clock transition’ (52S1/2 ∣Fg = 1, mF = 0ñ « ∣Fg = 2, mF = 0ñ) are relevant.OurODSEmethod is inspired by classical nuclear magnetic resonance spin-echo method, combined with optical detection. In contrast to other existing methods, like continuous-wave double-resonance (CW-DR) and Ramsey-DR, principles of the ODSE method allow suppression of decoherence arising from the inhomogeneity of the static magnetic field across the vapor cell, thus enabling measurements of intrinsic relaxation rates, as properties of the cell alone. Our experimental result for the coherence relaxation time, specific for the clock transition, measured with the ODSE method is in good agreement with the theoretical prediction, and the ODSE results are validated by comparison to those obtained with Franzen,CWDRand Ramsey-DR methods. The method is of interest for a wide variety of quantum optics experiments with optical signal readout.

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.

2009, Affolderbach, Christoph, Gruet, Florian, Miletic, Danijela, Mileti, Gaetano

We report on our development of a compact and high-performance laser-pumped Rubidium atomic frequency standard. The clock design is based on optical-microwave double-resonance using cw optical pumping, and a physical realization as simple as possible. Main development goals are a short-term instability of ≤ 6 × 10-13 τ-1/2 and a flicker floor of ≤ 1 × 10-14 up to one day. Here we discuss our approaches for controlling the clock's main physical parameters in view of optimized frequency stability.