Metrological characterization of the pulsed Rb clock with optical detection

We report on the implementation and the metrological characterization of a vapor-cell Rb frequency standard working in pulsed regime. The three main parts that compose the clock, physics package, optics and electronics, are described in detail in the paper. The prototype is designed and optimized to detect the clock transition in the optical domain. Specifically, the reference atomic transition, excited with a Ramsey scheme, is detected by observing the interference pattern on a laser absorption signal. \ The metrological analysis includes the observation and characterization of the clock signal and the measurement of frequency stability and drift. In terms of Allan deviation, the measured frequency stability results as low as $1.7\times 10^{-13} \ \tau^{-1/2}$, $\tau$ being the averaging time, and reaches the value of few units of $10^{-15}$ for $\tau=10^{4}$ s, an unprecedent achievement for a vapor cell clock. We discuss in the paper the physical effects leading to this result with particular care to laser and microwave noises transferred to the clock signal. The frequency drift, probably related to the temperature, stays below $10^{-14}$ per day, and no evidence of flicker floor is observed. \ We also mention some possible improvements that in principle would lead to a clock stability below the $10^{-13}$ level at 1 s and to a drift of few units of $10^{-15}$ per day

Study and characterization of a microcalorimeter thermostat

Peer Reviewe

Study and characterization of a microcalorimeter thermostat

A high-accuracy adiabatic microcalorimeter has been developed at Istituto Nazionale di Ricerca Metrologica (INRIM, Torino, Italy) for the realization of the radio frequency and microwave power primary power standard. The apparatus is intended to evaluate the efficiency of proper power sensors of thermoelectric or bolometric type by measuring their losses in terms of heat produced. These kind of measurements require a good thermal stabilization of the measurement chamber, therefore a dedicated thermostat has been designed, assembled and characterized at INRIM in order to obtain a thermal stability of +/-1 mK on a daily basis