Grégoire VALLET will defend his thesis on 13th of December 2018 at 2:00 pm on the subject “Cavity assisted non destructive detection on a strontium optical lattice clock”, realized in SYRTE, under the supervision of Sébastien Bize and co-supervised by Jérôme Lodewyck.

The defense will take place in room 235A (2nd floor) at ENS, 29 rue d’Ulm 75005 Paris, in front of a jury composed of Caroline Champenois, Robin Kaiser, Jakob Reichel and Morgan Michell.

Abstract:

I will start depicting the current landscape of atom clocks research providing you with the fundamental mechanisms, concepts and tools as well as the issues and challenges of the field, along with a detailed presentation of the working of the strontium optical lattice clock I have been working on during my training.
In a second step I will address the metrological aspect of my activity: evaluations of systematics effects inducing clock frequency shifts and participations to continental scale fiber links clock comparison campaigns. After presenting our most recent uncertainty budget I will expose our preliminary results in exploring one of these effects that we are the first group to report on in the case of strontium clocks and to include in our budget: the clock frequency shift induced by collisions between trapped strontium atoms and hot particles of background residual gas. I will as well expose the model I worked out for addressing this issue which unifies the two incompatible models available in the literature.
Finally I will discuss the research and experimental aspects of my work focused on the achievement of a non destructive detection system of atoms in cavity based on dispersive features of light-matter interaction, aiming at the reduction of two effects detrimental to optical lattice clocks stability: Dick effect and quantum projection noise. I will give as well prospects on the metrological gains expected from such technique.

Grégoire COGET will defend his thesis on 12th of December 2018 at 2:00 pm on the subject “Coherent population trapping Cs cell atomic clock with Auto-Balanced Ramsey interrogation protocol”, realized in FEMTO-ST Institute, under the supervision of Rodolphe Boudot.

The defense will take place at the Amphitheatre gagnepain of ENSMM, in front of a jury composed of Carlos Garrido Alzar, Martina Knoop, François Nez, François-Xavier Esnault, Rodolphe Boudot, Vincent Giordano.

Abstract:

This thesis reports a high-performance Cs vapor cell atomic clock based on coherent population trapping (CPT).
This simple-architecture clock prototype combines a DFB diode laser (895 nm, Cs D1 line), a fibered electro-optical modulator driven by an ultra-low phase noise microwave  frequency synthesizer, an acousto-optical modulator, a Michelson system, a buffer gas filled Cs vapor cell and FPGA-based low noise electronics.
The clock combines an optimized CPT pumping scheme, named push-pull optical pumping (PPOP), and a Ramsey-like pulsed interrogation, allowing the detection of high-contrast Ramsey-CPT fringes.
During this thesis has been implemented and adapted for this vapor-cell CPT clock, a novel interrogation protocol recently proposed by PTB for optical clocks, named Auto-Balanced Ramsey (ABR). This method, aiming to eliminate probe-induced frequency shifts, is based on the extraction of two error signals derived from two successive Ramsey sequences with different dark periods. The first feedback loop uses the error signal generated by the short Ramsey sequence to apply a phase-step correction to the local oscillator during the dark time that nulls the probe-field induced frequency shift. The second loop provides the means to stabilize the local oscillator frequency using the error signal derived from the long Ramsey sequence.
This ABR-CPT protocol, improved further with symmetrization (SABR-CPT), has allowed to reduce drastically the sensitivity of the clock frequency to laser power variations, by a factor 80 in comparison with a standard Ramsey-CPT interrogation. This CPT clock exhibits today the fractional frequency stability level of 2 10-13 τ-1/2, with best demonstrated mid-term stability in quiet conditions at the level of 2.5 10-15 at 10 000 s.
Annex laser spectroscopy studies in Cs microfabricated cells were also performed in this thesis. We note the preliminary demonstration of a frequency-stabilized laser using dual-frequency sub-Doppler spectroscopy in a Cs microcell, exhibiting an encouraging fractional frequency stability lower than 2 10-12 at 1 s. These short-term stability performances are 10 times better than those of microwave CPT-based chip-scale atomic clocks.

Jérémy BON will defend his thesis on 12th of December 2018 at 10:30 am on the subject “Résonateurs à ondes acoustiques de volume piégées à très basses températures : Application à l’optomécanique”, realized in FEMTO-ST Institute, under the supervision of Serge Galliou.

The defense will take plac eat the Amphitheatre Jules Haag of ENSMM, in front of a jury composed of Ludovic Bellon, Bernard Bonello, Pierre-François Cohadon, Gianpietro Cagnoli, Bernard Dulmet, Serge Galliou et Roger Bourquin.

Abstract:

For a few years, the Time and Frequency department in FEMTO-ST Insitute has been leading research about the behavior of Bulk Acoustic Wave (BAW) trapped in quartz crystal at cryogenic temperatures (near 4K).
The measured quality factor are around a few billions at few tens of MHz for such temperatures. Acoustical quartz cavities are therefore good candidates for ultrastable cryogenic frequency sources.
The work presented here is in the natural continuation of the research cited above. They aim at strenghtening the interest for quartz crystal, but also to consider alternative solutions with non-piezoelectric material with very-low acoustical losses, for which optical excitation is an option.
The following work can be summed up in three main parts:
– The first part is about the determination of a quartz crystal cut for which an turnover point exists in the frequency-temperature curve in the cryogenic region. Indeed, it is not enough to barely control the temperature in an ultrastable frequency source. Such an turnover point needs to be the operation point for thermal regulation. Searching a compensated cut arose the need for a preliminary measurements campaign of thermal coefficients of elastic coefficients of the material, which were unknown at low temperature.
It was then possible, based on these coefficients, to calculate and even realize a cut fulfilling the required condition.
– The second part had the objetive to demonstrate conceptually that using a quartz acoustical cavity as an optical cavity was feasable. In its basic scheme, a BAW quartz resonator is plano-convex (to ensure the trapping of the acoustic wave) and has electrodes (metal-made to ensure electrical excitation) deposited on each face. It has been demonstrated, both theoretically and experimentally, that such a geometry works fine as an optical cavity, with its corresponding advantages and limitations. This scheme is used for the optomechanical coupling discussed in the third part and constitutes the very base for more efficient optomechanical devices.
– The third part is dedicated to the evaluation of how efficient will such devices be while functioning at cryogenic temperature. A theoretical quantitication of the optomechanical coupling that these cavities might reach is also presented.
Producing an optomechanical cavity will allow avoiding the physical constraints imposed by the use of a cryogenerator and will open the way to the study of non-piezoelectric material with very low mechanical losses, similar or even lower than that of quartz.
This kind of experimentation also answers to the needs of other research teams working on quantum optomechanics or hybrid quantum systems (LKB, UWA, …) with which collaborations are currently being held.

Etienne VAILLANT will defend his thesis on 11th of December 2018 on the subject “Contribution à la mesure du bruit propre de résonateurs MEMS”, realized in FEMTO-ST with Fabrice Sthal et Joël Imbaud.

The French Optical Society (Société Française d’Optique) is happy to announce a new series of annual international thematic schools devoted to hot topics in optics and photonics, held every year at Les Houches School of Physics.
After more than 15 years of development, optical fiber links and optical frequency combs are now sufficiently mature to be spread and shared outside the time/frequency metrological institutes. The school follows on from the international development of optical fiber links and its objective is thus to broadcast among a wide community of physicist the possibilities of high precision measurement thanks to the optical fiber transfer of an optical frequency reference, coupled to a frequency comb. These setup enable any laboratory to access an ultrastable and accurate reference frequency which opens the way to high-precision experiments in a wide range of physical domain. In order to benefit from its metrological performance, the optical reference frequency disseminated by optical fiber links can then be transferred to a wide spectral range from RF to UV frequencies thanks to optical frequency combs. In addition, these combs are ideal tools for high-resolution atomic and molecular spectroscopy.
The attendants will learn both the basics, performance and limitations of these two tools and how to take advantage of them for high-precision measurements. The applications in sight concern for instance tests of fundamental physics, atomic and molecular high-resolution spectroscopy using either stabilized lasers or new spectroscopic methods, frequency transfer for radio astronomy and geodesy and novel applications concerning Earth observation.

High Precision Physics using an Optical Fibre Link and Optical Frequency Comb
22-26 April 2019, École de Physique des Houches (France).

=> More information.

La DGA et l’ONERA se proposent d’organiser les 26 et 27 mars 2019 les 5èmes Journées « Micro et Nano Technologies pour l’Inertiel ».

Ces journées se dérouleront sur le site de l’ONERA Palaiseau, 8 Chemin de la Hunière. Elles ont vocation à rassembler l’ensemble de la communauté française impliquée dans l’inertiel en créant un espace d’échange privilégié entre les donneurs d’ordre et les différents acteurs de l’industrie et du monde académique. Elles permettent aussi de dresser un état des lieux des développements , d’identifier les tendances et les nouveaux besoins applicatifs ou encore de détecter les éventuelles ruptures.

Pour ces 5èmes journées, nous nous proposons d’élargir les thèmes traditionnellement centrés sur les composants inertiels (accéléromètres, gyromètres, magnétomètres) et UMIs issus des micro/nano-technologies , aux composants temps/fréquence, et plus particulièrement axé sur l’apport des micro/nano technologies dans le domaine. Nous prévoyons aussi une session « rupture » autour de l’interférométrie à onde de matière, ses applications dans les mesures inertielles et les challenges associés dans la miniaturisation de ces composants.

Afin de bâtir le programme détaillé de ces journées, merci de nous faire part rapidement de vos intentions de communication. Le format retenu sera une communication orale de 20 mn, questions comprises, organisé en différentes sessions, avec une participation équilibrée entre les industriels/start-ups, les académiques et donneurs d’ordre.

L’inscription est gratuite mais obligatoire.

A first of his kind, the workshop “Use-cases from quantum technologies for sensing and metrology” aims to explore the use-cases from quantum technologies for sensing and metrology applications. The chosen method is based on a prospective analysis associating quantum technology experts, and technology prescribers in their field (research, industry or market), able to define the relevant performances, needs and ultimately markets.

Six technology areas will be considered, covering both use cases in research (may involve high-tech industry, or academia), where the highest performances are targeted, where the market sizes can be small and the cost may play a secondary role, and use cases for the end-user, where the typical market sizes are very large, the costs have to be low and the device sizes have (often) to be small. These areas are:

• Quantum enhanced magnetometry
• Gravimeters
• Detecting microwave radiations, and applications
• Detecting radiation at single photon level, and applications
• Time references
• Quantum enhanced interferometry, and applications

Be at the forefront of thinking about the impact of quantum technologies on sensors and metrology!

December 10-11, 2018 – Institut Néel (Grenoble, France).

⇒ More information and registration

We are pleased to announce the 7th European Frequency and Time Seminar (EFTS), Besancon, France, July 1-5, 2019.

The EFTS is an intensive full-week seminar intended to provide education and training with lectures and laboratory sessions. It targets a broad audience: Engineers, Ph.D. Students, Post-doc Fellows, Young Scientists, Newcomers, etc.

This seminar is original in the following:
· Broad spectrum of topics related to time and frequency
· Broad target audience, yet keeping high level education
· Balance between academic and applied issues
· True laboratory sessions (as opposite to demos). The attendees are expected to practice on a wide range of instruments made available.

At the 2019 EFTS, we plan 23 lectures, 12 H labs in small groups, visits at the Femto-ST Institute and the Observatory of Besancon, social events, and an Astronomy Session on the “exact time” from stars.

Registrations will only open at the end of January. However, pre-registrations (no invoice issued) are welcome.

Detailed program and Abstracts are being prepared, and will be available later. In the meanwhile, you can download the Abstracts of the previous edition.
You may also like the Enrico’s Chart of Phase Noise and Allan Variance.

Registration
January 2019: Registrations open.
Thursday, April 25, 2019: Early Birds (reduced rate) deadline.
Wednesday, June 12, 2019: Regular Participants (full rate) deadline.
Notice that there is a limited number of places set by the capacity of labs, first registered, first served.
A small number in excess can be allowed on a reduced version of the seminar (full lectures, and 4-6 H labs only). Contact us for availability and rate.

About
The EFTS is a non-profit seminar started in 2013 by Enrico Rubiola, and run every year at the Femto-ST Institute. It is sponsored by Gov, Academic and Int’l Institutions, and lives on the volunteer work of its Instructors and Staff.
The Femto-ST Institute is a French Gov lab affiliated to the National Research Council CNRS under the number UMR 6174.

EQTC 2019 is the 1st international conference of the European Quantum Flagship.
Join EQTC 2019 for a full coverage of European and International most prominent and recent advances in quantum technologies.
Basic science, communication, computing, simulation, sensing areas will each be covered through plenary and parallel sessions, as well as poster sessions.
EQTC 2019 will provide you with a full update on the European Flagship momentum, strategies and opportunities including reports from and discussions with the Strategic Research Agenda, Innovation, and Education Working Groups of the Quantum Flagship.
EQTC 2019 will be a unique opportunity to meet the European and International academic and industrial QT communities, and also learn about other issues such as standardization and communication of quantum technologies towards the general public.

Date and place: February 18-22, 2019. Grenoble, France.

=> More information and website.

Hélène PIHAN-LE BARS will defend her thesis on 15th of November 2018 at 2:00 pm on the subject “From atomic clocks to the MICROSCOPE mission: search for Lorentz invariance violations”, realized in SYRTE under the direction of Peter Wolf and co-supervised by Christine Guerlin.

The defense will take place in the conference room of the building 9 (castle) of the site of Meudon of Paris observatory – 5, place Jules Janssen, 92190 Meudon -, in front of a jury composed of Eric Gourgoulhon, Saïda Guellati-Khélifa, Robertus Potting, Joël Bergé and Isabelle Petitbon.

The defense will be in french and will be followed by a buffet.