[Bonnes ondes]Vincent Giordano awarded a European prize for his time-frequency research – Journal en direct

Major conference bringing together the greatest specialists in the field, the European Forum on Frequency and Time awarded its prestigious prize EFTF Award 2024 has Vincent GiordanoCNRS research director in the Time-Frequency department of the FEMTO-ST Institute, for the excellence and international impact of his scientific work.

Originally from Besançon, former student of ENSMMVincent Giordano was very early aware of the world of watchmakinga key that helped him open the doors of the Faculty of Sciences of Orsay, today part of the University of Paris-Saclay, to pursue a doctorate. THE atomic clocks are the central theme of his thesis, and remain at the heart of his research when he returns to Franche-Comté. Assigned to the LPMO, Oscillator Physics and Metrology Laboratory, he first proposesuse microtechnologies developed in Besançon to reduce the size of atomic clocksan idea too innovative in 1996 to arouse the expected interest. Since then, miniaturized atomic clocks have made their way from research laboratories to GPS receivers, and remain a spearhead of time-frequency research at the FEMTO-ST Institute.

With his team, in the early 2000s, Vincent Giordano succeeded in insert cesium atoms into the hearts of atomic clocks non-invasivelyaccording to a process guaranteeing respect for the extreme cleanliness of this cavity placed under vacuum.
The method represents a real breakthrough in technologyit has since been used by researchers and manufacturers around the world. “In the cavity, a material chosen for its properties releases the cesium atoms it contains, under the effect of its heating caused by laser radiation sent through a transparent wall,” summarizes Vincent Giordano.

On the advice of Jean-Jacques Gagnepain, a physicist in Besançon at the origin of the creation of the FEMTO-ST Institute, and at that time also scientific director at the CNRS, Vincent Giordano launched a research project on cryogenic oscillators.

Here, the researcher changes scale by focusing on the development of ultrastable oscillators, whose dimensions are similar to a cabinet. “The vibrations generated in a quartz resonator have the same function as the movements of the pendulum of a Comtoise clock : produce regular oscillations that make the heart of the clock beat. » If a quartz resonator makes a million oscillations before stopping, a billion is reached with a cryogenic resonator: this is the technology that Vincent Giordano is developing in his work.

The quartz is here replaced by corundum– a single crystal incorrectly called sapphire – whose characteristics make it possible to obtain impressive signal stability at a temperature of 6 K (- 267.15°C).

The cryogenic clocks are developed to order within the FEMTO-ST Institute itself, and marketed by FEMTO-Engineering. If they can be used for example in space to follow the position of satellites placed in distant orbits or on earth to measure the movement of tectonic plates, they are for the moment essentially responsible for the production of International Atomic Timel.

Copies are installed in dedicated observatories in England, China, Italy, South Korea, and an order is in progress for the Paris Observatory. The United States Naval Observatory in Washington, which has the best clocks in the world, has acquired three cryogenic clocks made in Besançon.