We present our studies on a compact high-performance continuous wave (CW) double-resonance (DR) rubidium frequency standard in view of future portable applications. Our clock exhibits a short-term stability of 1.4 × 10(-13) τ(-1/2), consistent with the short-term noise budget for an optimized DR signal. The metrological studies on the medium- to longterm stability of our Rb standard with measured stabilities are presented. The dependence of microwave power shift on light intensity, and the possibility to suppress the microwave power shift is demonstrated. The instabilities arising from the vapor cell geometric effect are evaluated, and are found to act on two different time scales (fast and slow stem effects). The resulting medium- to long-term stability limit is around 5.5 × 10(-14). Further required improvements, particularly focusing on medium- to long-term clock performance, are discussed.

Analysis of the mode composition of an X-band overmoded O-type Cerenkov high-power microwave oscillator Phys. Plasmas 19, 103102 (2012) Gap independent coupling into parallel plate terahertz waveguides using cylindrical horn antennas J. Appl. Phys. 112, 073102 (2012) A band-pass filter approach within molecular dynamics for the prediction of intrinsic quality factors of nanoresonators J. Appl. Phys. 112, 074301 (2012) A research of W-band folded waveguide traveling wave tube with elliptical sheet electron beam Phys. Plasmas 19, 093117 (2012) Additional information on Rev. Sci. Instrum. The design, realization, and characterization of a compact magnetron-type microwave cavity operating with a TE 011 -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 −13 τ −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.

We present a compact and frequency-stabilized laser head based on an extended-cavity diode laser. The laser head occupies a volume of 200 cm 3 and includes frequency stabilization to Doppler-free saturated absorption resonances on the hyperfine components of the 87 Rb D 2 lines at 780 nm, obtained from a simple and compact spectroscopic setup using a 2 cm 3 vapor cell. The measured frequency stability is ഛ2 ϫ 10 −12 over integration times from 1 s to 1 day and shows the potential to reach 2 ϫ 10 −13 over 10 2 −10 5 s. Compact laser sources with these performances are of great interest for applications in gas-cell atomic frequency standards, atomic magnetometers, interferometers and other instruments requiring stable and narrow-band optical sources.

We investigate the experimental sensitivity limit of a scalar optical magnetometer based on coherent population trapping on the D2 line of a thermal cesium vapor. We find the expected strong dependence on averaging time, with a detection limit below 4 pT for integration times longer than 1 s, limited by slow drifts of the cell temperature and of the applied test magnetic-field itself. A detailed noise analysis shows that for shorter averaging times the demonstrated limit of about 12 pT/ √ Hz is dominated by the frequency noise of the laser source. The magnetometer can be operated for real-time detection in flux densities up to at least milliteslas and is robust enough for application outside the laser laboratory.

We present a new characterisation technique for atomic vapor cells, combining time-domain measurements with absorption imaging to obtain spatially resolved information on decay times, atomic diffusion and coherent dynamics. The technique is used to characterise a 5 mm diameter, 2 mm thick microfabricated Rb vapor cell, with N2 buffer gas, placed inside a microwave cavity. Time-domain Franzen and Ramsey measurements are used to produce high-resolution images of the population (T1) and coherence (T2) lifetimes in the cell, while Rabi measurements yield images of the σ−, π and σ+ components of the applied microwave magnetic field. For a cell temperature of 90• C, the T1 times across the cell centre are found to be a roughly uniform 265 µs, while the T2 times peak at around 350 µs. We observe a 'skin' of reduced T1 and T2 times around the edge of the cell due to the depolarisation of Rb after collisions with the silicon cell walls. Our observations suggest that these collisions are far from being 100% depolarising, consistent with earlier observations made with Na and glass walls. Images of the microwave magnetic field reveal regions of optimal field homogeneity, and thus coherence. Our technique is useful for vapor cell characterisation in atomic clocks, atomic sensors, and quantum information experiments.