Séminaires

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    (en anglais) Assembling quantum matter one atom at a time

    C2N amphitheater, ,

    Antoine Browaeys

    Laboratoire Charles Fabry, Institut d’Optique, LCF, Palaiseau

    Séminaires

    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.

     

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    (en anglais) Optimized photonic integrated devices for free space applications

    C2N, Amphitheater,

    Daniele Melati

    C2N, , Palaiseau

    Séminaires

    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".

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    (en anglais) Silicon Photonics for LiDAR, Augmented Reality, Biophotonics, Quantum Engineering, and Beyond

    C2N amphitheater, ,

    Jelena Notaros

    Massachusetts Institute of Technology, , Cambridge

    Séminaires

    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.

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    (en anglais) LGTBQIA+ diversity in STEM: Current situation and actions for equality

    C2N - Université Paris-Saclay, Amphitheater, Palaiseau

    Aitor Villafranca Velasco

    Spanish National Research Council / PRISMA, , Madrid

    Séminaires

    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.

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    (en anglais) Imaging ultrafast and ultrasmall: Unraveling nanoscale electronic and magnetic behavior using time-resolved x-ray scattering

    C2N amphitheater, ,

    Roopali Kukreja

    UC Davis, , Davis, CA

    Séminaires

    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).

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    (en anglais) ION-X and Spin-Ion, two start-ups located at the C2N

    C2N, Amphitheater, Palaiseau

    Thomas Hiriart (ION-X) and Marie Drouhin (Spin-Ion)

    Start-up "ION-X" and Start-up "Spin-Ion", , Palaiseau

    Séminaires

    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.
     

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    Rebound effects, LEDs and the role of technology in the ecological transition

    C2N amphitheater, ,

    Bruno GAYRAL

    CEA-Grenoble / IRIG / PHELIQS / NPSC, , Grenoble

    Séminaires

    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.

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    Les merveilleux nuages; que faire du nucléaire ?

    C2N amphitheater, ,

    Harry Bernas

    CNRS-Université Paris-Saclay, ,

    Séminaires

    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)

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    (en anglais) First C2N Colloquium 2024 - Quantum dots : a journey from solid-state physics to quantum technologies

    C2N - Université Paris-Saclay, Amphitheater, Palaiseau

    Pascale Senellart

    CNRS-Centre de Nanosciences et de Nanotechnologies, C2N, Palaiseau

    Séminaires

    Semiconductor quantum dots have emerged as interesting quantum emitters for quantum technologies. First synthetized in the laboratories of France Telecom in the mid 80s, their quantum properties have been unraveled in 1994 by Jean-Yves Marzin and Jean-Michel Gérard [1]. Progressively, quantum dots have been shown to behave as artificial atoms, combining the great potential for quantum optics of natural atoms, with unique features arising from their solid-state environment.

    In this talk, I will discuss how our team at C2N contributed to this journey from solid-state nanophotonics to quantum technologies. I will fist explain how we have progressively developed efficient sources of single and entangled photons  [2] that are now commercialized by the C2N spin-off Quandela. These devices allow implementing small-scale quantum computing protocols with 6 photons [3]. To scale-up, we recently reached an important milestone where multiple photons are entangled with a single spin [4]. Finally, I will illustrate how the maturity of our devices now allow us to go back to fundamental studies such as revisiting the process of spontaneous emission [5,6] or studying energetic exchanges in the quantum realm [7].

    [1] J. -Y. Marzin, et al.,  Phys. Rev. Lett. 73, 716 (1994)

    [2] N. Somaschi, V. Giesz et al, Nature Photonics 10, 340-345,  (2016)

    [3] N. Maring et al.,  arXiv:2306.00874

    [4] N. Coste et al., Nature Photonics (2023)

    [5] J. Loredo et al, Nature Photonics 13, 803 (2019)

    [6] S. Wein et al, Nature Photonics 16, 374 (2022)

    [7] I. Maillette de Buy Wenniger, Physical Review Letter (2023)

    Keywords: quantum dots, microcavities, single photons, quantum computing

    Bio

    Graduated from École Polytechnique and Doctor in Quantum Physics from Université Paris 6, Pascale Senellart joined the CNRS in 2001. She was appointed senior researcher in 2011 and associate professor at Polytechnique in 2014. Her research activity is at the interface between nanosciences, semiconductor physics and quantum optics. She received the CNRS Silver Medal in 2014, the Prix Mergier-Bourdeix in 2021, the Prix Jean Ricard in 2023 and was elected at the French Science Academy in 2022. She is  co-founder and scientific advisor of the C2N spin-off Quandela who develops solutions for optical quantum computing.

    Welcome at 9:30 am with a coffee - croissant time