Realization of a high power optical trapping setup free from thermal lensing effects

Transmission of high power laser beams through partially absorbing materials modifies the light propagation via a thermally-induced effect known as thermal lensing. This may cause changes in the beam waist position and degrade the beam quality. Here we characterize the effect of thermal lensing associated with the different elements typically employed in an optical trapping setup for cold atoms experiments. We find that the only relevant thermal lens is represented by the $TeO_2$ crystal of the acousto-optic modulator exploited to adjust the laser power on the atomic sample. We then devise a simple and totally passive scheme that enables to realize an inexpensive optical trapping apparatus essentially free from thermal lensing effects

Realization of a Cold Mixture of Fermionic Chromium and Lithium Atoms

We report on the production of a novel cold mixture of fermionic $^{53}$Cr and $^{6}$Li atoms delivered by two Zeeman-slowed atomic beams and collected within a magneto-optical trap (MOT). For lithium, we obtain clouds of up to $4 \,10^8$ atoms at temperatures of about $500\,\mu$K. A gray optical molasses stage allows us to decrease the gas temperature down to $45(5)\,\mu$K. For chromium, we obtain MOTs comprising up to $1.5\, 10^6$ atoms. The availability of magnetically trappable metastable $D$-states, from which $P$-state atoms can radiatively decay onto, enables to accumulate into the MOT quadrupole samples of up to $10^7$ $^{53}$Cr atoms. After repumping $D$-state atoms back into the cooling cycle, a final cooling stage decreases the chromium temperature down to $145(5)\,\mu$K. While the presence of a lithium MOT decreases the lifetime of magnetically trapped $^{53}$Cr atoms, we obtain, within a 5 seconds duty cycle, samples of about $4\, 10^6$ chromium and $1.5\,10^8$ lithium atoms. Our work provides a crucial step towards the production of degenerate Cr-Li Fermi mixtures.Comment: 14 pages, 8 figure

Definition of the Future Skills Needs of Job Profiles in the Renewable Energy Sector

The growth of the renewable energy industry is happening at a swift pace pushed, by the emergence of Industry 4.0. Smart technologies like artificial intelligence (AI), Big Data, the Internet of Things (IoT), Digital Twin (DT), etc. enable companies within the sector of renewable energies to drastically improve their operations. In this sectoral context, where upgraded sustainability standards also play a vital role, it is necessary to fulfil the human capital requirements of the imminent technological advances. This article aims to determine the current skills of the renewable energy industry workforce and to predict the upcoming skill requirements linked to a digital transition by creating a unified database that contains both types of skills. This will serve as a tool for renewable energy businesses, education centers, and policymakers to plan the training itinerary necessary to close the skills gap, as part of the sectoral strategy to achieve a competent future workforce.This research was partly funded by (a) the European Union through the Erasmus Plus Programme (Grant Agreement No. 2018-3019/001-001, Project No. 600886-1-2018-1-DE-EPPKA2-SSA-B)*, (b) the 4gune cluster, Siemens Gamesa and Aalborg University through the project “Identification of the necessary skills and competences for professionals of the future renewable energy sector”, and (c) Lantek, Inzu Group, Fundación Telefónica and Fundación BBK, partners of the Deusto Digital Industry Chair

Absolute frequency measurement of a Yb optical clock at the limit of the Cs fountain

We present the new absolute frequency measurement of ytterbium (171Yb) obtained at INRiM with the optical lattice clock IT-Yb1 against the cryogenic caesium (133Cs) fountain IT-CsF2, evaluated through a measurement campaign that lasted 14 months. Measurements are performed by either using a hydrogen maser as a transfer oscillator or by synthesizing a low-noise microwave for Cs interrogation using an optical frequency comb. The frequency of the 171Yb unperturbed clock transition ${^1}$S$_0\rightarrow {^3}$P0 results to be 518 295 836 590 863.44(14) Hz, with a total fractional uncertainty of $2.7 \times 10^{-16}$ that is limited by the uncertainty of IT-CsF2. Our measurement is in agreement with the Yb frequency recommended by the Consultative Committee for Time and Frequency. This result confirms the reliability of Yb as a secondary representation of the second and is relevant to the process of redefining the second in the International System of Units on an optical transition

High accuracy Yb optical lattice clock: frequency comparisons and contributions to International Atomic Time

Irene Goti Ph.D thesis. Politecnico di Torino, Doctoral Program in Metrology (35thcycle) ABSTRACT: During my PhD at the Politecnico di Torino, I worked at the Italian National Institute of Metrological Research (INRiM) in the field of frequency standards. In particular, in these three years, my research activity has been focused on the improvement and characterization of IT-Yb1, a Ytterbium optical lattice clock developed at INRiM. In the last decades, a great effort has been made to develop optical clocks, which are considered the most promising candidates for the redefinition of the second in the International System of Units (SI). Indeed, optical clocks have the potential to improve by several orders of magnitude the accuracy of the current definition of the second, which is based on the hyperfine transition of the ground state of the Caesium atom. During these three years, I have succeeded in improving both the accuracy of IT-Yb1 and its robustness. In particular, I have characterized IT-Yb1, achieving a fractional frequency systematic uncertainty of 2×10−17, the smallest uncertainty ever reported for our clock. To reach this goal, I worked on the implementation of an upgraded optical setup for the realization of a vertical optical lattice and on the characterization of several systematic shifts affecting the clock frequency, such as the lattice shift and the DC Stark shift. Moreover, I worked on the robustness and the clock’s reliability, trying to make its operation as continuous as possible. Significantly, in the last two years, IT-Yb1 has proven to be very reliable, operating almost continually for 14 months with an uptime of up to 75% in some weeks. The highlights of my PhD are summarized in the following. First, an absolute frequency of IT-Yb1 was performed against the primary frequency standard developed at INRiM, the Caesium fountain clock IT-CsF2. In addition, in the last few years, IT-Yb1 has participated in several international comparison campaigns in collaboration with other European and Asian National Metrology Institutes. Furthermore, IT-Yb1 is among the eight optical clocks that have ever submitted data to the Bureau International des Poids et Mesures (BIPM) to contribute to the calibration of the International Atomic Time (TAI). Remarkably, in the last year, IT-Yb1 has regularly contributed to the steering of TAI for 14 consecutive months, showing impressive continuity and robustness. All these results are a clear demonstration of the importance of IT-Yb1 in the international scenario of optical clocks and represent a significant contribution to the future redefinition of the SI second based on an optical standard. Finally, during the third year of the Ph.D., I spent four months with an Erasmus+Traineeship fellowship at the Laboratoire Charles Fabry in Palaiseau (France), where I worked on the Cyclopix project. In this experiment, the light-scattering of a Rb atomic sample trapped in an optical dipole trap is studied to observe the collective effects in the light emitted by the atoms. This internship was a great opportunity to learn new cooling and trapping techniques, such as optical tweezers, that can be useful for the realization of a new generation of optical clocks.This work is supported by: the European Metrology Program for Innovation and Research (EMPIR) Projects 18SIB05 ROCIT and 20FUN08 Nextlasers, which have received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme

High accuracy Yb optical lattice clock: frequency comparisons and contributions to International Atomic Time

During my PhD at the Politecnico di Torino, I worked at the Italian National Institute of Metrological Research (INRiM) in the field of frequency standards. In particular, in these three years, my research activity has been focused on the improvement and characterization of IT-Yb1, a Ytterbium optical lattice clock developed at INRiM. In the last decades, a great effort has been made to develop optical clocks, which are considered the most promising candidates for the redefinition of the second in the International System of Units (SI). Indeed, optical clocks have the potential to improve by several orders of magnitude the accuracy of the current definition of the second, which is based on the hyperfine transition of the ground state of the Caesium atom. During these three years, I have succeeded in improving both the accuracy of IT-Yb1 and its robustness. In particular, I have characterized IT-Yb1, achieving a fractional frequency systematic uncertainty of 2×10−17, the smallest uncertainty ever reported for our clock. To reach this goal, I worked on the implementation of an upgraded optical setup for the realization of a vertical optical lattice and on the characterization of several systematic shifts affecting the clock frequency, such as the lattice shift and the DC Stark shift. Moreover, I worked on the robustness and the clock’s reliability, trying to make its operation as continuous as possible. Significantly, in the last two years, IT-Yb1 has proven to be very reliable, operating almost continually for 14 months with an uptime of up to 75% in some weeks. The highlights of my PhD are summarized in the following. First, an absolute frequency of IT-Yb1 was performed against the primary frequency standard developed at INRiM, the Caesium fountain clock IT-CsF2. In addition, in the last few years, IT-Yb1 has participated in several international comparison campaigns in collaboration with other European and Asian National Metrology Institutes. Furthermore, IT-Yb1 is among the eight optical clocks that have ever submitted data to the Bureau International des Poids et Mesures (BIPM) to contribute to the calibration of the International Atomic Time (TAI). Remarkably, in the last year, IT-Yb1 has regularly contributed to the steering of TAI for 14 consecutive months, showing impressive continuity and robustness. All these results are a clear demonstration of the importance of IT-Yb1 in the international scenario of optical clocks and represent a significant contribution to the future redefinition of the SI second based on an optical standard. Finally, during the third year of the Ph.D., I spent four months with an Erasmus+Traineeship fellowship at the Laboratoire Charles Fabry in Palaiseau (France), where I worked on the Cyclopix project. In this experiment, the light-scattering of a Rb atomic sample trapped in an optical dipole trap is studied to observe the collective effects in the light emitted by the atoms. This internship was a great opportunity to learn new cooling and trapping techniques, such as optical tweezers, that can be useful for the realization of a new generation of optical clocks

High accuracy Yb optical lattice clock: frequency comparisons and contributions to International Atomic Time

L'abstract è presente nell'allegato / the abstract is in the attachmen

High accuracy Yb optical lattice clock: frequency comparisons and contributions to International Atomic Time

Ph.D. defence presentation, Politecnico di Torino.This work is supported by: the European Metrology Program for Innovation and Research (EMPIR) Projects 18SIB05 ROCIT and 20FUN08 Nextlasers, which have received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme

Dataset for the absolute frequency measurement of IT-Yb1 relative to IT-CsF2

Dataset of the comparison of the atomic clocks at INRIM between June 2021 and September 2022. Results discussed in Goti et al., Absolute frequency measurement of a Yb optical clock at the limit of the Cs fountain, Metrologia, 60, 035002 (2023). The involved atomic clocks are the Cs fountains IT-CsF2 and the Yb optical lattice clock IT-Yb1. Data is organized in folders. The data in the folder named 'INRIM_ITYb1-INRIM_ITCsF2-USO' is obtained making use of an optical-to-microwave chain. The data in the folder 'INRIM_ITYb1-INRIM_ITCsF2' is collected using an hydrogen maser as transfer oscillator. In the folders data is separated is one file per day. Data is reported as fractional frequency ratios in bins of 864 s. Timetags are reported in modified Julian date (MJD). A validity flag is given where 0 = invalid, valid otherwise. Each folder includes a yaml file with metadata required for generalized data processing as in [Lodewyck et al., 2020]. The Python package used for data processing can be found on github