Abstract

Research into the environmental footprint of research activities has gained momentum in the past three years, thanks in particular to the creation of the Labos 1point5 research network. I will briefly present the functioning and initial results of this collaborative effort. In the first part, I'll discuss the estimation of the carbon footprint (1) and the most relevant emission sources, that are highly dependent on the research discipline: air travel (2), purchasing (3), ventilation (4) and research infrastructures (5). In the second part, I will introduce examples of footprint reduction policies and the new tools available to build these policies (in particular the Labos in transition network). I'll conclude with an opening discussion of the implications of these results for organising low-carbon research.

(1) J. Mariette et al, Env. Res.: Infr. Sust. 2022. (https://dx.doi.org/10.1088/2634-4505/ac84a4)
(2) T. Ben-Ari et al, Env. Res. Lett. 2024. (https://eartharxiv.org/repository/view/5995/)
(3) M. De Paepe et al, Biorxiv 2023 (https://www.biorxiv.org/node/3267221.abstract).
(4) A. Estevez-Torres et al, Green. Chem. 2024 (http://dx.doi.org/10.1039/D3GC03668E)
(5) J. Knödlseder et al, Nat. Astron. 2022 (https://doi.org/10.1038/s41550-022-01612-3)

About the author

André Estevez-Torres is a senior researcher at CNRS. He worked for 20 years in experimental biophysics on the self-organization of molecular systems with contributions in the engineering of reaction-diffusion and active matter systems. He started a transition to sustainability sciences in 2021 and he now specializes in monetary methods for quantifying the environmental footprint in the research sector. He is a co-developer of GES 1point5 and currently co-directs the Labos 1point5 research network.

Charge density wave (CDW) systems have known a renewed interest in recent years, since its discovery near the superconducting phase of many compounds [1]. It mostly appears in low-dimensional, quasi-1D or 2D systems, in the form of a periodic modulation of both crystal lattice and electron density, associated with gap opening in the corresponding electron branches [2]. CDWs are sensitive to a wide range of excitations that can modify their wavelength or amplitude: thermal, electrical, mechanical etc. In recent years, the electronic properties of 2D systems have proven very sensitive to strain which boosted the activity on strain engineering in these systems. At LPS, we recently developed a cryogenic biaxial tensile stress device to mechanically deform 2D systems over a wide temperature range (15-400K) and explore the strain-induced phase diagrams. It is compatible with transport, X-ray diffraction and optical measurements, which allows us to follow both structural and electronic properties in the same samples. After describing the device, we will present the results obtained in the case of TbTe3, which undergoes a CDW orientational transition under deformation, which goes together with an increase of more than 30K of the transition temperature [3]. This effect is directly linked to the change in symmetry of the structure, as demonstrated thanks to the combination of XRD and transport measurements.
[1] J. Tranquada et al., Nature 375, 561–563 (1995)
[2] P. Monceau, Electronic crystals: an experimental overview, Advances in Physics 61, 325 (2012)
[3] A. Gallo-Frantz et al., Nat. Comm. 15, 3667 (2024)

Abstract

Over the last twenty years, physicists have learned to manipulate individual quantum objects: atoms, ions, molecules, quantum circuits, electronic spins... It is now possible to build "atom by atom" a synthetic quantum matter. By controlling the interactions between atoms, one can study the properties of these elementary many-body systems: quantum magnetism, transport of excitations, superconductivity... and thus understand more deeply the N-body problem. More recently, it was realized that these quantum machines may find applications in the industry, such as finding the solution of combinatorial optimization problems.

This seminar will present an example of a synthetic quantum system, based on laser-cooled ensembles of individual atoms trapped in microscopic optical tweezer arrays. By exciting the atoms into Rydberg states, we make them interact, even at distances of more than ten micrometers. In this way, we study the magnetic properties of an ensemble of more than a hundred interacting ½ spins, in a regime in which simulations by usual numerical methods are already very challenging. Some aspects of this research led to the creation of a startup, Pasqal.

Biography

Antoine Browaeys is a senior staff Scientist at CNRS. He studied at the Ecole Normale Supérieure in Cachan (France) and did his ph’D under Alain Aspect at the Institut d’Optique (2000). He spent two years at NIST in the Laser Cooling group led by W.D. Phillips. He was hired as a scientist at CNRS in 2003. He is working on experiments manipulating individual cold atoms and small, dense atomic clouds. Part of his research led to the creation of the Pasqal company, that he is a co-founder and scientific adviser of.

He was awarded the Aimé Cotton Prize of the French Physical Society in 2007 and the Silver medal of CNRS in 2021. He was elected member of the French academy of science in decembre 2023.

Abstract

Photonic integration offers great potentialities for the realization of compact, light-weight, and low-cost systems for free-space applications, noteworthy in the field of 3D imaging and optical communications. However, several shortcomings still limit the widespread applicability of integrated solution, e.g., low efficiencies, narrow operational bandwidth, and polarization sensitivity. The use of metamaterial and metasurfaces, combined with innovative design approaches based on optimization and machine learning, represents powerful tools to overcome these limitations. In this seminar, we will discuss our recent advances in the realization of highly-performing devices for free-space applications and optical beam control, with a particular focus on integrated grating antennas and metasurfaces.

About the speaker

Daniele Melati is a CNRS researcher at the Centre de Nanosciences et de Nanotechnologies and an Adjunct professor at Carleton University, Ottawa. He received his M.Sc. in Telecommunication Engineering in 2010 and his Ph.D. in Information Engineering in 2014, both from Politecnico di Milano. Before joining C2N in 2020, he was a Research Associate at the National Research Council Canada, where he started his work on the use of optimization and machine learning technique for the development of advanced silicon photonic devices. At C2N, he focuses his research activity on the development of photonic integrated devices, optical antennas and metasurfaces for the generation and control of free-space wave-fronts. This work is currently supported by the ERC Starting Grant "BEAMS".

Abstract
By enabling the integration of millions of micro-scale optical components on compact millimeter-scale
computer chips, silicon photonics is positioned to enable next-generation optical technologies that facilitate
revolutionary advances for numerous fields spanning science and engineering. This talk will highlight our
work on developing novel silicon-photonics-based platforms, devices, and systems that enable innovative
solutions to high-impact problems in areas including augmented-reality displays, LiDAR sensing for
autonomous vehicles, free-space optical communications, optical trapping for biophotonics, 3D printing,
and trapped-ion quantum engineering.

Biography
Jelena Notaros is the Robert J. Shillman Career Development Assistant Professor of Electrical Engineering
and Computer Science at the Massachusetts Institute of Technology. She received her Ph.D. and M.S.
degrees from MIT in 2020 and 2017, respectively, and B.S. degree from the University of Colorado Boulder
in 2015. Jelena was one of three Top DARPA Risers, a 2018 DARPA D60 Plenary Speaker, a 2023 NSF
CAREER Award recipient, a 2021 Forbes 30 Under 30 Listee, a 2021 MIT Robert J. Shillman Career
Development Chair recipient, a 2020 MIT RLE Early Career Development Award recipient, a 2015 MIT
Herbert E. and Dorothy J. Grier Presidential Fellow, a 2015-2020 NSF Graduate Research Fellow, a 2024
OSA CLEO Highlighted Talk Award recipient, a 2019 OSA CLEO Chair's Pick Award recipient, a 2022
OSA APC Best Paper Award recipient, a 2022 OSA FiO Emil Wolf Best Paper Award Finalist, a 2014
IEEE Region 5 Paper Competition First Place recipient, a 2023 MIT Louis D. Smullin Award for Teaching
Excellence recipient, a 2018 MIT EECS Rising Star, a 2014 Sigma Xi Undergraduate Research Award
recipient, and a 2015 CU Boulder Chancellor's Recognition Award recipient, among other honors.

Did you know that one out of three trans scientists suffer harassment at their workplace? Or that only 14% of bisexual STEM professionals are out of the closet? Were you aware of how discrimination impacts scientific output? In this seminar we will look into the current situation of LGBTQIA+ professionals working in STEM, and discuss simple actions which can help creating safer and more inclusive spaces for everyone.

Bio

Aitor Villafranca Velasco is a Tenured Scientist at the Spanish National Resarch Council (CSIC), where his current research interests include silicon photonics and microspectrometry. He is the founder of spin-off company Alcyon Photonics, and non-profit scientific association PRISMA, where he also acts as Director of Education.

Ultrafast laser control of correlated materials has emerged as a fascinating avenue of manipulating magnetic and electronic behavior at femtosecond timescales. Ultrafast manipulation of these materials has also been envisioned as a new paradigm for next generation memory and data storage devices. Numerous studies have been performed to understand the mechanism underlying laser excitation. However, it has been recently recognized that spatial domain structure and nanoscale heterogeneities can play a critical role in dictating ultrafast behavior. In this talk, I will discuss methods and our recent results which capture material behavior at nanoscale lengthscales and femtosecond-nanosecond timescales. I will describe our recent experimental studies using emerging synchrotron techniques and free electron laser such as European XFEL and FERMI. In the first part of my talk, I will discuss our results on ultrafast magnetization dynamics where we uncovered a symmetry-dependent behavior of the ultrafast response. Labyrinth domain structure with no translation symmetry exhibit an ultrafast shift in their isotropic diffraction peak position that indicates their spatial rearrangement. On the other hand, anisotropic domains with translation symmetry do not exhibit any modification of their anisotropic diffraction peak position. In the second part of my talk, I will focus on x-ray imaging of correlated oxides and discuss spatially dependent ultrafast response observed in complex oxides such as rare-earth nickelates. These intriguing observation suggests preferential, texture-dependent paths not only for the transport of angular momentum, but also for structural rearrangements. These measurements provide us with a unique way to study and manipulate spin, charge and lattice degrees of freedom.

Short Bio Roopali Kukreja joined Materials Science and Engineering department at UC Davis as an Assistant Professor in Fall 2016.  She received her B.S. in Metallurgical Engineering and Materials Science from the Indian Institute of Technology Bombay in 2008 and then her M.S. and Ph.D. degrees in Materials Science and Engineering from Stanford University in 2011 and 2014, respectively.  Prior to her appointment at UC Davis, Kukreja worked as a postdoctoral researcher at the UC San Diego, with Profs. Oleg Shpyrko (Physics Department) and Eric Fullerton (Center for Magnetic Recording Research). Her research interests at UC Davis focuses on ultrafast dynamics in nanoscale magnetic and electronic materials, time resolved X-ray diffraction and imaging techniques, thin film deposition and device fabrication. She is recipient of Melvin P. Klein Scientific development award (2015), AFOSR Young Investigator Award (2018), NRC Faculty Development Award (2019), DOE Early Career Award (2021) and NSF Early Career Award (2022).

ION-X
Established in 2021 by CNRS and the startup studio Technofounders, the company ION-X aims to become one of the global leaders in space mobility. By providing one of the most efficient satellite propulsion systems on the market, ION-X intends to enable its customers to maximize the lifespan and value of their orbiting infrastructure. Based on technology patented by CNRS and using an inert, green, and non-toxic propellant, the ION-X thruster aims to demonstrate top performances in terms of thrust and energy efficiency.
Thomas Hiriart, CEO of the company, will expand on the ElectroHydroDynamic (EHD) propulsion technology developed by Jacques Giérak, Co-Founder of the company and recipient of the 2023 CNRS Innovation Medal. He will also present the resulting competitive advantages of the product and will provide an intro on the underlying market of small satellites in low Earth orbit.

Spin-Ion
Irradiation with He+ ion : a manufacturing process to improve the performance of spintronic chips.
To address the challenges of the digital transition, Spin-Ion Technologies, a start-up resulting from two decades of academic research at IEF and then C2N, has developed a patented manufacturing process based on a He+ ion beam to enhance the performance of spintronic chips. This solution enables atomic control of magnetic materials used notably in MRAM memories, magnetic sensors, and neuromorphic devices, markets currently experiencing significant growth. Having successfully passed the proof-of-concept stage on test chips, the deep-tech startup has forged strategic partnerships with industrial leaders to initiate the pre-industrialization phase of its technology. Spin-Ion Technologies is currently focusing its efforts on a neuromorphic chip for specific embedded AI applications (edge computing).
Marie Drouhin, a Software Engineer at Spin-Ion Technologies and a graduate of the C2N, will present the technology developed by Spin-Ion, market expectations, and the startup's development challenges.
 

The citation for the 2014 Nobel Prize in Physics was for “the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources”, thus suggesting that visible LEDs for lighting lead to global energy savings. As is well known among economists (but perhaps less among physicists, engineers and policy makers), the various rebound effects can severely affect the overall energy-consumption gain (if any) when a more energy-efficient technology comes to market. It is an open question to assess whether the III-N LED technology actually leads to energy savings.
I will discuss the notion of rebound effect (notably direct and indirect rebound effects) in general and then for the case of the III-N LED technology, notably in light of the surprisingly scarce literature on the topic. I will then discuss the forecasted rise of the micro-display market for virtual-reality and augmented-reality applications (arguably much less of a basic need for humanity than lighting), which is based on the same technology as LEDs for lighting. In this sense, III-N LEDs illustrate quite well that it is not possible to claim a priori that a technological innovation will lead to energy savings. I will conclude by discussing what I think this implies for the ethics of scientific communication.

C’est d’abord la structure sociale et économique qui détermine la manière d’utiliser l’énergie. Or les sociétés changeront profondément dans les trois décennies à venir sous la pression des changements du climat et du vivant. Le projet annoncé de “nouveau nucléaire” en France contribuerait-il à une adaptation soutenable de la société à ces transformations, d’ici 2050 ? Ce devra(it) être le sujet d’un débat public, informé et démocratique. On propose un bref examen de l’histoire et de la faisabilité industrielle, économique et sociale du nucléaire face aux urgences imposées par les changements planétaires.

Harry Bernas est physicien (nanosciences, matériaux irradiés). Il a dirigé le Centre de sciences nucléaires et de sciences de la matière (CNRS-Université Paris-Saclay). Récemment il a publié, outre des travaux en matière d’histoire contemporaine des sciences et des rapports sciences-technologie-société, un ouvrage, L’Île au bonheur (éd. Le Pommier, 2022). Ce séminaire est issu de son dernier livre (éd. Seuil, sept. 2023)