Coherent spin dynamics of rare-earth doped crystals in the high-cooperativity regime

Rare-earth doped crystals have long coherence times and the potential to provide quantum interfaces between microwave and optical photons. Such applications benefit from a high cooperativity between the spin ensemble and a microwave cavity -- this motivates an increase in the rare earth ion concentration which in turn impacts the spin coherence lifetime. We measure spin dynamics of two rare-earth spin species, $^{145}$Nd and Yb doped into Y$_{2}$SiO$_{5}$, coupled to a planar microwave resonator in the high cooperativity regime, in the temperature range 1.2 K to 14 mK. We identify relevant decoherence mechanisms including instantaneous diffusion arising from resonant spins and temperature-dependent spectral diffusion from impurity electron and nuclear spins in the environment. We explore two methods to mitigate the effects of spectral diffusion in the Yb system in the low-temperature limit, first, using magnetic fields of up to 1 T to suppress impurity spin dynamics and, second, using transitions with low effective g-factors to reduce sensitivity to such dynamics. Finally, we demonstrate how the `clock transition' present in the $^{171}$Yb system at zero field can be used to increase coherence times up to $T_{2} = 6(1)$ ms.Comment: 8 pages, 5 figure

White Paper #1: Fundamental Physics

The Standard Model (SM) of particle physics and General Relativity (GR) are the two pillars of our current understanding of Nature. Both theories have been probed individually with ever increasing precision and are consistent with nearly all experimental observations. However, they fail to explain dark matter, dark energy, or the imbalance between matter and anti-matter in the universe. Yet, dark matter and dark energy represent 95% of the energy content of our universe while known matter (atoms, molecules) amounts to only 5%. Today, dark matter and dark energy have an unknown origin and there is a great deal of experimental and theoretical activity to solve this puzzle. In summary, the clustering of large-scale structure and the accelerated behaviour of cosmic fluid could be addressed whether finding out new (unknown) forms of matter or assuming that gravity behaves in different ways at infrared scales. Furthermore, the lack of a self-consistent theory of Quantum Gravity prevents the unification of SM and GR at ultraviolet scales. This is one of the biggest challenges that theoretical physics is facing today. String theory or loop quantum gravity are good candidates to solve this puzzle and interestingly both of them foresee violations of the Einstein's Equivalence Principle. With that respect the Einstein's Equivalence Principle assumes a central role in the search for a quantum theory of gravity. The open problems in fundamental physics investigated in this white paper are: (i) Validity of the Einstein's Equivalence Principle; (ii) Origin and nature of dark matter and dark energy; (iii) Decoherence and collapse models in quantum mechanics; (iv) Quantum many-body physics. They will be addressed from different research corners and with different experimental methods: (i) Ultracold atoms; (ii) High stability and accuracy atomic clocks; (iii) Matter-wave interferometry; (iv) Classical and quantum links. The cosmos is a particularly attractive laboratory as it provides particles (cosmic rays) or objects (black holes, neutron stars) which are not produced in manmade laboratories. Space is also an excellent environment for high precision physics as the absence of atmosphere or drag-free satellites provide unique observation opportunities. For instance the MICROSCOPE mission has taken advantage of extremely long free-fall conditions in Earth orbit to set the record in testing the Equivalence Principle beyond what has been possible on Earth. Large velocity, velocity variations and large variation of the gravitational potential are accessible on board a spacecraft, thus providing wide signals for testing GR. Finally, the huge free propagation distances available in space provide very long baselines to test the spacetime metric with high performance links both classical and quantum

Cold atoms in space: community workshop summary and proposed road-map

We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies

Cold atoms in space: community workshop summary and proposed road-map

We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies.publishedVersio

Cold atoms in space: community workshop summary and proposed road-map

We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies

Terrestrial Very-Long-Baseline Atom Interferometry:Workshop Summary

This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more km-scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions

Situation sociolinguistique et écriture du gascon aujourd'hui

Pour que la graphie du gascon réponde aux besoins actuels, ce travail étudie d'abord ces besoins (Ière partie), puis tente de définir la graphie (IIème partie). Le gascon est d'abord montré comme langue romane autonome, tant pour les linguistes que pour ses locuteurs naturels. Mais ceux-ci, principalement des ruraux, tendent à disparaitre, et la transmission de la langue repose surtout sur l'enseignement, handicapé par une graphie qui représente mal la parole. Pour y remédier, on va d'abord étudier l'écriture gasconne du Moyen âge à aujourd'hui, où deux grands systèmes s'opposent : le moderne, facile et populaire, et le classique, à base médiévale, appliqué par l'école depuis 1968. Concrètement, deux chapitres proposent alors les améliorations à leur apporter; au classique, pour le rendre plus fidèle à la phonologie gasconne; mais il reste élitiste et antipédagogique; au moderne ensuite, pour pallier ses quelques défauts. Un lexique orthographique partiel illustre ces propositions.The aim of this work is to put Gascon spelling in line with the needs of today. We thus begin with a study of these needs (Part I), and then attempt to define the written form (Part II). Gascon is first defined as a Romance language in its own right, by linguists and by native speakers. The latter, who are mainly country people, are gradually disappearing, and transmission of the language relies mainly on teaching, which is hindered by an orthography that imperfectly represents speech. To remedy this, we first review the Gascon writing system, from the Middle Ages to the present, with two distinct systems : the modern one, easy and popular; and the classical, mediaeval-based one, taught in schools since 1968. Two further chapters propose improvements to these systems; to the classical one, to bring it closer to Gascon phonology (however, it remains elitist and un-pedagogical); and to the modern one, to improve its few defects. These propositions are exemplified by a partial lexiconRENNES2-BU Centrale (352382101) / SudocSudocFranceF

Situation sociolinguistique et écriture du gascon aujourd'hui

Pour que la graphie du gascon réponde aux besoins actuels, ce travail étudie d'abord ces besoins (Ière partie), puis tente de définir la graphie (IIème partie). Le gascon est d'abord montré comme langue romane autonome, tant pour les linguistes que pour ses locuteurs naturels. Mais ceux-ci, principalement des ruraux, tendent à disparaitre, et la transmission de la langue repose surtout sur l'enseignement, handicapé par une graphie qui représente mal la parole. Pour y remédier, on va d'abord étudier l'écriture gasconne du Moyen âge à aujourd'hui, où deux grands systèmes s'opposent : le moderne, facile et populaire, et le classique, à base médiévale, appliqué par l'école depuis 1968. Concrètement, deux chapitres proposent alors les améliorations à leur apporter; au classique, pour le rendre plus fidèle à la phonologie gasconne; mais il reste élitiste et antipédagogique; au moderne ensuite, pour pallier ses quelques défauts. Un lexique orthographique partiel illustre ces propositions.The aim of this work is to put Gascon spelling in line with the needs of today. We thus begin with a study of these needs (Part I), and then attempt to define the written form (Part II). Gascon is first defined as a Romance language in its own right, by linguists and by native speakers. The latter, who are mainly country people, are gradually disappearing, and transmission of the language relies mainly on teaching, which is hindered by an orthography that imperfectly represents speech. To remedy this, we first review the Gascon writing system, from the Middle Ages to the present, with two distinct systems : the modern one, easy and popular; and the classical, mediaeval-based one, taught in schools since 1968. Two further chapters propose improvements to these systems; to the classical one, to bring it closer to Gascon phonology (however, it remains elitist and un-pedagogical); and to the modern one, to improve its few defects. These propositions are exemplified by a partial lexiconRENNES2-BU Centrale (352382101) / SudocSudocFranceF

Étude analytique des phases sulfurées du gîte de Rouez

Electron microprobe analysis of pyrrhotite chalcopyrite and sphalerite of the massive sulfide deposit of Rouez, Sarthe (France) emphasizes some characteristics of the mineralization. Two phases of pyrrhotite, monoclinic and hexagonal, have been recognized, in association with homogeneous populations of chalcopyrite and sphalerite containing about 13 mole percent FeS. Granting a stable association of these minerals, we try to replace this assemblage in the P — T systems obtained under hydrothermal conditions. The temperature of equilibrium suspected is close to local metamorphism conditions. Then, the volcano-sedimentary massive sulfide deposit of Rouez is looked to have been homogeneized under metamorphic conditions after its deposition.L'étude analytique ponctuelle à la microsonde électronique de trois sulfures : pyrrhotite, chalcopyrite et sphalérite, contenus dans l'amas sulfuré de Rouez, Sarthe (France) met en lumière quelques caractères minéralogiques de ce gisement. Elle permet de reconnaître la présence de deux phases de pyrrhotite, l'une hexagonale et l'autre monoclinique, en association avec des populations homogènes de chalcopyrite et de sphalérite, dont la teneur moyenne en fer est de l'ordre de 13 % moles FeS. En admettant que ces différents sulfures soient en équilibre, on peut examiner la paragenèse du gisement de Rouez à la lumière de diagrammes thermodynamiques connus et des résultats de synthèses hydrothermales. On constate que la température d'équilibre correspondante est compatible avec le type de métamorphisme ayant affecté le corps minéralisé et son enveloppe. On peut alors envisager que le gisement de Rouez proche, sur le plan métallogénique, du modèle «amas sulfuré volcano-sédimentaire », ait évolué depuis sa formation et soit en équilibre avec les conditions du métamorphisme, c'est-à-dire du dernier événement thermique.Safa Philippe, Lafitte Michel, Maury Roger. Étude analytique des phases sulfurées du gîte de Rouez. In: Bulletin de Minéralogie, volume 105, 1, 1982. pp. 51-56