(en anglais) High peak power pulses and solitons in quantum cascade laser combsCentre de Nanosciences et de Nanotechnologies, Amphithéâtre, Palaiseau
Thanks to progress in Quantum cascade laser combs, mid-infrared dual comb spectroscopy has recently achieved very short time resolution (10s) and very high accuracy (1m Absorbance), as well as high resolution (~3MHz) measurements over a full bandwidth of 55cm-1 with an acquisition time of only 120ms.
To further improve the performance of these spectrometers, we will discuss improvement of the QCL comb laser sources using ring QCLs and RF injection in specially designed devices. We demonstrated recently sub-picosecond pulses with high peak powers, in the range of watts. We also recently showed that ring QCLs can emit temporal solitons.
Jérôme Faist was born in Switzerland and obtained his Ph.D. in Physics in 1989 from the Swiss Institute of Technology in Lausanne. He then worked successively at IBM Rueschlikon (89-91) and Bell Laboratories (91-97). He was nominated full professor in the physics institute of the University of Neuchâtel (1997) and then full professor in the ETH Zurich (2007).
His key contribution to the development of the quantum cascade laser was recognized by a number of awards. His present interests include the development of mid-infrared and terahertz quantum cascade lasers and frequency combs and the physics of strong light-matter coupling Terahertz metamaterial resonators.
(en anglais) Quantum imaging with entangled photonsCentre de Nanosciences et de Nanotechnologies, A005-A007, Palaiseau
Quantum imaging harnesses quantum properties of light and their interaction with the environment to go beyond the limits of classical imaging or to implement unique imaging modalities. In conventional quantum imaging systems, a non-classical state of light illuminates an object from which an image is formed on a set of photodetectors. In this respect, sources of entangled photon pairs are very prolific. Over the last decades, they have been used to achieve super-resolution  and sub-shot-noise imaging , as well as to develop new imaging approaches such as ghost imaging , quantum illumination  and quantum holography .
However, most of these experimental schemes require to measure intensity correlations between many spatial positions in parallel, a task that is much more delicate than forming an image by photon accumulation. Originally, this was performed using raster-scanning single-pixel single-photon detectors, but this process is very photon inefficient and time-consuming. In recent years, these systems were substituted by single-photon sensitive cameras, such as electron multiplied charge coupled device (EMCCD), to achieve faster quantum imaging with photon pairs and move this field closer to practical applications [6,7].
In this presentation, I will detail the technique that we have developed to image entangled photon pairs using cameras. I will then describe some specific approaches that were implemented thanks to this novel imaging ability, including quantum image distillation  and entanglement-enabled quantum holography . Finally, I will discuss the perspectives and general interest of developing quantum imaging system based on entangled photon pairs.
 Boto, Agedi N., et al. "Quantum interferometric optical lithography: exploiting entanglement to beat the diffraction limit." Physical Review Letters 85.13 (2000): 2733.
 Brida, Giorgio, Marco Genovese, and I. Ruo Berchera. "Experimental realization of sub-shot-noise quantum imaging." Nature Photonics 4.4 (2010): 227-230.
 Pittman, Todd B., et al. "Optical imaging by means of two-photon quantum entanglement." Physical Review A 52.5 (1995): R3429.
 Defienne, Hugo, et al. "Quantum image distillation." Science advances 5.10 (2019): eaax0307.
 Defienne, Hugo, et al. "Polarization entanglement-enabled quantum holography." Nature Physics 17, 591-597 (2021).
 Moreau, Paul-Antoine, et al. "Realization of the purely spatial Einstein-Podolsky-Rosen paradox in full-field images of spontaneous parametric down-conversion." Physical Review A 86.1 (2012): 010101.
 Edgar, Matthew P., et al. "Imaging high-dimensional spatial entanglement with a camera." Nature communications 3.1 (2012): 1-6.
(en anglais) Lessons in Nanotechnology from the ribosomeCentre de Nanosciences et de Nanotechnologies, Amphithéâtre, Palaiseau
Biological nervous systems have been a source of inspiration for realizing new computing paradigms in electronics and optical systems for decades. While the single operation of current traditional CMOS technologies is approaching the energy consumption (~1 pW) of the most basic operation in biological nervous systems, an action potential, the action potential is far from being the most fundamental operation in a living cell. At the heart of molecular biology is the central dogma, which describes how genetic information is sequentially transferred from DNA into RNA into proteins that are used for all cellular life. The nano-machine that translates mRNA into proteins is the ribosome and in the past twenty years there have been enormous developments in understanding its biological functionality. Its energy consumption is ~5 orders of magnitude smaller than an action potential and approaches the Landauer limit of computation, but its use as an inspiration for new computing paradigms is still in its infancy. This is most likely because an understanding of how energy is used to realize translation is still not well understood. In this talk, I present an alternative way to model the dynamics of the ribosome using network theory. This concise representation can be used to track dynamic changes in different ribosomal states and understand its global dynamical nature. I describe some of the differences between ribosome functionality and artificially realized nano-machines.
Figure : Heatmap of correlations between the interactions in 6 different files. (perfect correlation/decorrelation = 0/1).
Link : https://us02web.zoom.us/j/86277738532 -Find a clickable link in the attached file bellow
(en anglais) Nanoparticles: a tool of choice for biomedical applicationsCentre de Nanosciences et de Nanotechnologies, , Palaiseau
The field of nanotechnology is booming, significantly impacting our society and creating a growing enthusiasm in biotechnology and biomedical science. During this seminar, I will therefore present 3 research projects in which nanoparticles play a central role, whether in the understanding of a biological phenomenon or in the development of diagnostic tools. 1) Understanding of the toxicity induced by inhaled nanoparticles After inhalation, nanoparticles can reach the pulmonary alveoli, where gas is exchanged. They then encounter the pulmonary surfactant, i.e. the fluid lining the epithelial cells. In this work, the interaction of model bare nanoparticles (latex, metal oxides, silica) with a biomimetic pulmonary fluid (composed of phospholipids and proteins assembled in vesicles) was studied and we showed that this interaction was of electrostatic origin. We also observed a wide variety of resulting hybrid structures, which attests to the complexity of the phospholipid/particle interaction. In addition, we succeeded in formulating particles covered with a supported bilayer derived from pulmonary surfactant and exhibiting remarkable stability in biological environment. Finally, the role of the pulmonary surfactant on the interactions between nanoparticles and alveolar epithelial cells was studied, demonstrating the importance of the pulmonary surfactant in the protection of the alveolar epithelium. 2) Conception of a dosimeter doped with gold nanoparticles for radiotherapy
With the latest generation of radiation therapy devices, no dosimeter can be used to achieve a satisfactory in vivo dosimetry. In this respect, we aimed to develop a new dosimeter based on gold nanoparticles.
We first quantified the degradation of conventional dyes (here azo dyes) under gamma irradiation, thus producing a reference dosimeter. We then synthetized gold nanoparticles and added them to dye solutions since they are known to increase radical production. Unexpectedly, an overall decrease of sensitization was observed. We demonstrated that this phenomenon was probably due to the dye propensity to adsorb onto the gold nanoparticles and to the fact that the radicals overproduced by nanoparticles preferentially attack dyes adsorbed at their surface.
Our results underlined the need for an in-depth physicochemical characterization of the dye/nanoparticle systems to reveal the mechanisms underlying their gamma irradiation.
3) Development of antigenic tests based on luminescent nanoparticles
The simple, rapid, portable, and specific detection of biomolecules and pathogens in complex media is of growing interest in many fields. Lateral Flow Assays (LFAs), and more specifically antigen tests, are a central tool in this context. However, the standard gold nanoparticle-based LFAs lack sensitivity and generally do not provide quantitative measurements or simultaneous detection of multiple targets.
In order to overcome these limitations, we combined a simple homemade reader coupled to a smartphone with the remarkable optical properties of lanthanide ions using luminescent nanoparticles as probes. We first demonstrated a gain in sensitivity of more than one order of magnitude compared to the reference LFA when detecting staphylococcal enterotoxins, approaching or surpassing the ELISA sensitivity for these biomolecules. Then, three toxins were simultaneously detected without any loss of sensitivity. Our method thus constitutes a powerful approach to detect multiple proteins and could be the basis of future sensitive and portable bioassays or diagnostic tests.
(en anglais) Silicon nitride: towards a complete toolbox for nonlinear integrated photonicCentre de Nanosciences et de Nanotechnologies, Amphithéâtre, Palaiseau
Nonlinear optics describes the behaviour of light in a nonlinear medium, exploiting higher orders of the material susceptibility. It allows us to, for example, change the colour of a light beam, change its shape or process light with light. Nonlinear optical phenomena are the basis of many devices used in optical communication systems, optical sensing or material research and enable a wide range of novel applications, and the need for the integration of nonlinear functionalities to the chip scale is evident
It is now well established that silicon nitride offers many advantages for integrated nonlinear photonics. Pushed by recent progress in fabrication, we now have access to very low loss waveguides while maintaining large flexibility in terms of dispersion engineering, both essential for the design of efficient nonlinear systems. As such many nonlinear optical demonstrations, mainly based on 3rd order effects in the telecom band, have been performed. Pushing the applications over the entire accessible spectral range of silicon nitride, from the visible to the middle infrared, as well as offering completely new horizon of applications by inducing effective 2nd-order effects, would provide new and essential elements to the nonlinear integrated photonic toolbox. In this talk I will quickly review our work on systems based on the inherent 3rd order effects, and we then cover how we can leverage all-optical poling to enhance the typically weak 2nd-order nonlinearities of the platform.
Camille-Sophie Brès is an associate professor at EPFL in the institute of Electrical Engineering. She received her bachelor degree with honors in electrical engineering from McGill University, Canada, in 2002. She then moved to the USA where she obtained her PhD in electrical engineering from Princeton University in 2006. After a post-doctoral position at the University of California San Diego she joined EPFL as a tenure track professor and director of the Photonic Systems Laboratory in 2011. Her work focusses on leveraging and enhancing nonlinear processes in optical waveguides for the optimization of all-optical signal processing, light generation and sensing by exploiting dispersion engineering, material properties, and architectural features. She was awarded the early career Women in Photonics Award from the European Optical Society in 2016, as well as ERC starting (2012), Consolidator (2017) and Proof of Concept (2019) grants.
(en anglais) Proximity coupling graphene to a TMD: moiré effects on coupled Fermi seas, and Rydberg excitons as probes for graphene fractional quantum hall statesCentre de Nanosciences et de Nanotechnologies, Amphithéâtre, Palaiseau
Alexander Popert1, Tomasz Smolenski1, Yuya Shimazaki1, Puneet Murthy1, Thibault Chervy1, Kenji Watanabe2, Takashi Taniguchi3 , Martin Kroner1, Atac Imamoglu1
1 Institute for Quantum Electronics, ETH Zürich, CH-8093 Zürich, Switzerland
2 Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
3 International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
Placing 2D materials in close proximity to each other greatly enriches them, leading to phenomena like interlayer excitons hosting a hole in one layer and an electron in the other layer . Also the superconductivity hosted in twisted bilayer graphene and twisted bilayer WSe2 critically relies on the coupling between the two layers, giving rise to a new system with vastly different properties from its host materials.
In this talk, we'll explore structures where the 2D semiconductor MoSe2 is in close proximity to graphene. Using Rydberg excitons in MoSe2 as sensitive probes for the dielectric environment , we demonstrate that fractional quantum hall states in graphene can be detected by purely optical means. We further discuss the regime where both graphene and the TMD are doped. We observe a periodic charge transfer between graphene and the TMD as a function of doping which we attribute to the moiré potential arising between the graphene and the hBN substrate.
As more and more of 2D materials research is directed to emergent phenomena between different 2D materials, we believe that these results will stimulate important discussions.
1. Shimazaki, Y., Schwartz, I., Watanabe, K. et al. Strongly correlated electrons and hybrid excitons in a moiré heterostructure. Nature 580, 472–477 (2020)
2. Xu, Y., Horn, C., Zhu, J. et al. Creation of moiré bands in a monolayer semiconductor by spatially periodic dielectric screening. Nat. Mater. 20, 645–649 (2021)
Find a clickable link in the attached file below
Please click the link below to join the webinar: https://us02web.zoom.us/j/86277738532
Webinar ID: 862 7773 8532
(en anglais) Towards Quantum Communication with Entangled Photons from Quantum DotsC2N - Centre de Nanosciences et de Nanotechnologies, Amphithéâtre, Palaiseau
The prospect of using the quantum nature of light for long distance quantum communication keeps spurring the search and investigation of suitable sources of entangled photons. Semiconductor quantum dots (QDs), also dubbed “artificial atoms”, are arguably one of the most attractive, as they can generate pairs of polarization-entangled photons with high efficiency and with near-unity degree of entanglement. Despite recent advances, however, the exploitation of photons from QDs in advanced quantum communication protocols remains a major open challenge.
In this talk, I will discuss how photons generated by a GaAs quantum dot  can be used to implement quantum teleportation [2, 3] and entanglement swapping  protocols with fidelities above the classical limit. Moreover, I will present our first steps towards the construction of a quantum-dot based quantum network for secure communication within the campus of Sapienza University of Rome . A discussion on future challenges and perspectives [6, 7] will conclude the talk.
 D. Huber, et al., Phys. Rev. Lett. 121, 033902 (2018)
 M. Reindl et al., Science adv. 4, eaau1255 (2018)
 F. Basso Basset et al., NPJ Quantum Inf. 7, 7 (2021).
 F. Basso Basset et al., Phys. Rev. Lett. 123,160501 (2019)
 F. Basso Basset et al., Science adv. 7, eabe6379 (2021)
 M. Reindl et al., Nano Letters 17, 4090 (2017)
 M. Reindl et al., Appl. Phys. Lett. 118, 100502 (2021)
(en anglais) Synthesis of (111)-oriented perovskite oxides and the role of antiferromagnetic spin structure on magnetic reconstructions at ferromagnetic/antiferromagnetic perovskite interfacesCentre de Nanosciences et de Nanotechnologies, Amphithéâtre, Palaiseau
Perovskite oxides are technologically interesting because of their strong structure-property coupling, with interesting functional properties ranging from ferromagnetism, ferroelectricity to high-temperature superconductivity. Here I will give an overview of our work on synthesis of atomically smooth (111)-oriented oxides and discuss the effect of crystalline facet on growth and control of functional properties. Epitaxial thin films and heterostructures of antiferromagnetic (AF) LaFeO3, ferromagnetic La0.7Sr0.3MnO3 are used as model system. I will especially focus on how anisotropic strain engineering permits to tailor the AF Neel vector in epitaxial single crystalline LaFeO3 thin films. To impose anisotropic strain, we rely on the (111) pseudocubic facet of orthorhombic scandate- and gallate-based oxide substrates. X-ray studies confirm a lowering of LaFeO3 symmetry, from orthorhombic in bulk to monoclinic or triclinic, depending on the choice of substrate and the magnitude of anisotropic strain, in thin films, in accordance with DFT calculations. Epitaxial engineering allows us to efficiently tune the magnetic anisotropy from bi-axial in bulk to uniaxial in our thin films, as inferred from soft x-ray spectroscopy. By increasing the LaFeO3 thickness transition of the uniaxial spin direction takes place, a change from an out-of-plane to an in-plane AF spin axis above 16 d111-layers. I will also discuss the possibilities that anisotropic strain engineering offers to tune the interface AF spin texture between LaFeO3 and a ferromagnet in a deterministic fashion, as confirmed by soft x-ray spectroscopy and spin-polarized neutron reflectivity. To probe the interface spin texture between LaFeO3 and La0.7Sr0.3MnO3 a combined soft x-ray spectroscopy, neutron reflectometry, magnetometry, TEM and DFT study was performed, and correlations between local AF order and concurrent structural reconstructions at interfaces will be addressed.
Professor Tybell has ~20 years of experience in oxide electronics materials science, and co-founder of the oxide electronics group at NTNU. He focuses on synthesis and nanostructuring of epitaxial complex oxide thin heterostructures and superlattices. Present research includes interface engineering of ferroelectric and magnetic systems, and the possibility for symmetry engineering of functional properties. Parallel to research he has devoted effort to teaching and administration and has had the responsibility to direct and develop a cross-disciplinary nanotechnology effort at NTNU and developed a new 5-year curriculum for the MSc study program within electronic systems design and innovation. Currently he is deputy director of Department of Electronics and Telecommunications with responsibility for research.
find a clickable link in the attached file bellow
(en anglais) Addressing plasmonic hot-spots: from DNA-based self-assembly to far-field wavefront shapingCentre de Nanosciences et de Nanotechnologies, Amphithéâtre, Palaiseau
Light-matter interactions in condensed media at room-temperature are fundamentally limited by electron-phonon coupling. For instance, while the excitation cross-section of an isolated atom, or of a single quantum emitter at cryogenic temperatures, can reach one half of the wavelength of light squared (meaning that ~50% of incoming photons will interact for a diffraction-limited excitation); this value is reduced by 6-7 orders of magnitude for a fluorescent molecule or for a colloidal quantum dot at room temperature because of homogeneous phonon broadening. In order to render the exceptional optical properties of single quantum systems (such as single-photon emission and nonlinearities) efficiently accessible at room temperature and in condensed media, it is essential to enhance and optimize these interaction cross-sections.
Over the last two decades, plasmonic resonators have shown amazing promise towards this goal thanks to their ability to enhance optical fields by several orders of magnitude in deeply sub-wavelength volumes. However, the nanoscale dimensions of these field enhancements or “hot-spots” mean that it is extremely difficult to exploit them in a controlled and reproducible way. At Institut Langevin, we develop two approaches in order to achieve this:
-We introduce, in a deterministic way, a controlled number of quantum emitters in the nanoscale hot-spot between two gold nanoparticles using a DNA-based self-assembly strategy. Using this approach, we were able to enhance single-photon emission from fluorescent molecules by more than two orders of magnitude in a weak-coupling regime. I will discuss recent experiments where we reach a strong-coupling regime between a plasmonic resonator and five organic molecules.
-We actively control the seemingly random plasmonic hot-spots featured by disordered gold surfaces using far-field wavefront shaping. In practice, by tuning the phase of a pulsed excitation, we ensure the constructive interference of plasmonic modes that are delocalized over several microns on the surface; leading to a local enhancement of the nonlinear luminescence of gold by more than two orders of magnitude.
Find a clickable link in the attached file below
(en anglais) Exploring antiferromagnetic order at the nanoscale with a single spin microscopeCentre de Nanosciences et de Nanotechnologies, Amphithéâtre, Palaiseau
Experimental methods allowing for the detection of single spins in the solid-state, which were initially developed for quantum information science, open new avenues for the development of highly sensitive quantum sensors. In that context, the electronic spin of a single nitrogen-vacancy (NV) defect in diamond can be used as an atomic-sized magnetometer, providing an unprecedented combination of spatial resolution and magnetic sensitivity under ambient conditions. In this talk, I will illustrate how scanning-NV magnetometry can be used as a powerful tool for exploring condensed-matter physics, focusing on chiral spin textures in antiferromagnetic materials.
Dr. Vincent Jacques is a CNRS research associate in the team “Solid-state quantum technologies” at the Laboratoire Charles Coulomb (Montpellier). His research interests cover several fundamental and applied topics related to the applications of “artificial atoms” in quantum technologies. Such topics include quantum optics, spin physics, and quantum sensing with the development of highly-sensitive magnetometers based on NV defects.
Find a clickable link in the attached file below