arXiv subjects

Claudio Eligio Calosso

Publications and source records attributed to Claudio Eligio Calosso.

3 recordsLinked to original sources

arXiv2025

An Accessible Formulation for Defining the SI Second Based on Multiple Atomic Transitions

The atomic transitions employed in the best of today's optical clocks are a strong foundation for the upcoming redefinition of the SI second. Including multiple transitions in the definition offers increased accuracy, a robust diversity of implementations and would drive continuous performance validation through frequency comparisons. The cost is that such a definition is more complex to articulate and feared to be challenging to implement. We show that it can be made more approachable to intuition, illustration and implementation through formulating this ensemble definition of the SI second in terms of the weighted arithmetic mean of normalized atomic transition frequencies. This definition produces the same results as the presently discussed option up to second order terms of order 10^-30 or below.

physics.atom-ph↗

arXiv2016

High-performance coherent population trapping clock with polarization modulation

We demonstrate a vapor cell atomic clock prototype based on continuous-wave (CW) interrogation and double-modulation coherent population trapping (DM-CPT) technique. The DM-CPT technique uses a synchronous modulation of polarization and relative phase of a bi-chromatic laser beam in order to increase the number of atoms trapped in a dark state, i.e. a non-absorbing state. The narrow resonance, observed in transmission of a Cs vapor cell, is used as a narrow frequency discriminator in an atomic clock. A detailed characterization of the CPT resonance versus numerous parameters is reported. A short-term frequency stability of $3.2 \times 10^{-13} τ^{-1/2}$ up to 100 s averaging time is measured. These performances are more than one order of magnitude better than industrial Rb clocks and comparable to those of best laboratory-prototype vapor cell clocks. The noise budget analysis shows that the short and mid-term frequency stability is mainly limited by the power fluctuations of the microwave used to generate the bi-chromatic laser. These preliminary results demonstrate that the DM-CPT technique is well-suited for the development of a high-performance atomic clock, with potential compact and robust setup due to its linear architecture. This clock could find future applications in industry, telecommunications, instrumentation or global navigation satellite systems.

physics.atom-ph↗

arXiv2015

Evaluating Optical Fiber Links with Data Filtering and Allan Deviation

In this paper we propose a simple method to reject the high-frequency noise in the evaluation of statistical uncertainty of coherent optical fiber links. Specifically, we propose a preliminary data filtering, separated from the frequency stability computation. In this way, it is possible to use the Allan deviation as estimator of stability, to get unbiased data, which are representative of the noise process affecting the delivered signal. Our approach is alternative to the use of the modified Allan deviation, which is largely adopted in this field. We apply this processing to the experimental data we obtained on a 1284 km coherent optical link for frequency dissemination, which we realized in Italy. We also show how the so-called Lambda-type commercial phase/frequency counters can be used to this purpose.

physics.ins-det↗