Seminars

First, I introduce our design of reservoir computer using MRAM technology. Then, I will talk about recent progresses in making Brownian computer using skyrmions. 
Brownian computing is a method to perform calculation with ultra-low energy consumption.
Up to now, we have succeeded in making a Hub (branch of skyrmion channel) and in voltage control of the diffusion. Ratchet and C-join are also essential devices that we need to realize. 

Seminars

How can we make individual photons interact with each other, or with a single stationary quantum bit? I will show that efficient light-matter interfaces can be developed to address these challenges, using semiconductor quantum dots in optimized microcavity structures. This led to a number of achievements in the last decade, including:

- The engineering of an effective photon-photon interaction, using an optical nonlinearity at the single-photon limit.

- The demonstration of an efficient spin-photon interaction, using the spin of a confined semiconductor hole as a stationary quantum bit. The current efforts for realizing deterministic quantum gates and fundamental quantum experiments, based on a new generation of spin-based devices, will also be discussed.

Loïc Lanco was hired in 2007 as an Associate Professor at University Paris Diderot, after a PhD in Laboratory « Quantum Materials and Phenomena » (MPQ), and a one year post-doc at the Laboratory for Photonics and Nanosctructures (LPN, now C2N). His research activity focuses on light-matter interfacing at the single-photon level, using semiconductor quantum dot / cavity structures. He was nominated at the Institut Universitaire de France in 2019. He headed the Physics BSc in Paris Diderot from 2014 to 2018.

Seminars

There is a need for the development of comprehensive, multi-scale theoretical tools in the search for better materials. This is essentially at the core of the recent “materials genomics/informatics” initiatives that seek to accelerate materials discovery through the use of computations across length and time scales, supported by judicious experimental work. In this talk we will apply these principles
to understand pyroelectric, electrocaloric, elastocaloric, and flexocaloric properties of ferroelectric materials. Pyroelectrics can convert heat into electricity by cycling around thermally- and electricallyinduced polarization changes, where the energy density scales with the product of the polarization change and applied field. The challenges in realizing caloric energy conversion system are multi-scale
and multi-faceted, requiring a combination of first principles computations, phenomenological theory, classical thermodynamics, materials synthesis, and eventually system design [1]. We will discuss our successes and challenges with relating modeled to measured material properties for bulk and epitaxial thin film ferroelectrics. We will provide specific examples related to electrocaloric, elastocaloric, and flexocaloric properties of ferroelectrics [2,3].
1. S. P. Alpay, J. V. Mantese, S. Trolier-McKinstry, Q. M. Zhang, and R. W. Whatmore, “Next Generation Electrocaloric and
Pyroelectric Materials for Solid State Electrothermal Energy Interconversion,” MRS Bulletin 39, 1099 (2014).
2. H. Khassaf, T. Patel, S. P. Alpay, “Combined Intrinsic Elastocaloric and Electrocaloric Properties of Ferroelectrics,” J. Appl.
Phys. 121, 144102 (2017).
3. H. Khassaf, T. Patel, R. J. Hebert, and S. P. Alpay, “Flexocaloric Response of Epitaxial Ferroelectric Films,” J. Appl. Phys. 123,
024102 (2018).
Contacts: lucie.krzaczkowski@cea.fr, philippe.lecoeur@u-psud.fr, brahim.dkhil@centralesupelec.fr

Seminars

The Hong-Ou-Mandel (HOM) interference is the most significant photonic effect, one with no counterpart in classical optics. The interference is fragile–it is sensitive to distinguishability in all degrees of freedom–and normally occurs on the order of very short path length differences–micrometers to millimeter. Despite these limitations, HOM interference has proven application in quantum computing, metrology and quantum foundations.

We report HOM interference observed after more than 100m path length difference between photons from a cavity-enhanced spontaneous parametric down-conversion source, equating to the 84th HOM revival. In addition to producing HOM revivals, the source can alternatively generate two-photon NOON states. These two features result from the unique half waveplate ’flip trick’ of our source effectively producing two distinct frequency combs, each of which can be temporally accessed. This combination makes our source a novel metrological tool to allow enhanced precision on a sub-wavelength scale in a quantum-secure way.

W. Y. Sarah Lau completed a double degree in Science and Education (secondary) at the University of Queensland (UQ). After working briefly as a high school teacher Sarah has returned to UQ as a PhD student in Andrew White’s Quantum Technology Lab. She initially focused on quantum foundations and has since transitioned to work on the narrowband single photon source, which has moved down to the Australian National University in Canberra for integration with their quantum memory setup. Sarah now also works there and is investigating squeezing from the narrowband setup alongside the quantum memory integration.

Seminars

Silicon is one of the most well-known materials, and the main actor in today electronics. Despite this, silicon superconductivity was only discovered in 2006 in laser doped Si:B samples. Laser annealing is instrumental to cross the superconductivity threshold, as the required doping is above the solubility limit, and cannot be reached using conventional micro-electronic techniques. Laser doping allows the realization of epitaxial, homogeneous, thin silicon layers (5-300 nm) with extreme active doping as high as 11 at. %, and without the formation of B aggregates. Silicon is a disordered superconductor, with a lower carrier density (1020 – 1021 cm-3) than metallic superconductors, a critical temperature modulable with doping from 0 to 0.7 K, and a relatively high resistivity that allows to easily match the devices to the void impedance.

After demonstrating all-silicon SQUIDs and Josephson junctions, we have realized microwave silicon resonators, working in the 1-10 GHz range and with quality factors about 4000. We have shown a strong non-linear response with power, observing a Kerr coefficient of the order of 300 Hz/photon where less than 1 Hz/photon was expected. This suggests that, once the losses sources identified and reduced, silicon resonators may be promising candidates for Kinetic Inductance Detectors. To better understand the losses and recombination mechanisms, we have measured the relaxation dynamics of the resonators following a light or a microwave pulse.

Francesca CHIODI is Maître de Conférences at Université Paris Sud. She joined the ‘Laser epitaxy’ group in 2011, to work on laser ultra-doping of Si and Ge, and to develop and investigate the first superconducting Si devices. She graduated from ENS, Paris, obtained a PhD at LPS, on the dynamics of long SNS Josephson junctions, and joined as a Post-Doc at Material Sciences Dept., Cambridge, UK, on triplet superconductivity in inhomogeneous SFS Josephson junctions.

Seminars

Organo-metallic chemical vapor epitaxy is a well-established technique used for the growth of highly complex heterostructures combining a variety of semiconductor alloys with a multitude of applications in photonics. Research in MOVPE at the C2N focuses at pushing the limits of what is feasible with this technique, tackling the growth of novel alloys such as (Si)GeSn, challenging due to their inherent immiscibility, and advanced heterostructures, such as quantum cascade devices, challenging to the complexity of their structure that consists of hundreds of layers that are only a few monolayers thick.
After a general introduction to the technique and an overview of the activity at the C2N, the seminar will delve more deeply in the subject of GeSn alloys and InAlAs/InGaAs quantum cascade structures, and showcase how one can achieve the required level of control over matter to produce novel photonic devices.

Konstantinos Pantzas is a researcher at the Centre de Nanosciences et de Nanotechnologies (C2N). His research evolves around the MOCVD growth of new materials and complex heterostructures for mid-infrared photonics. He received his predoctoral education at Supelec and holds a PhD in Material Science from the University of Lorraine in 2013 and a PhD in Electrical and Computer Engineering from the Georgia Institute of Technology in 2015. Prior to his appointment to the CNRS in 2016, he worked as was a post-doctoral research fellow at the Laboratoire de Photonique et de Nanostructures (ex-LPN, now C2N).

Seminars

Magnetostriction links the shape of a magnetic material to its magnetization direction. Kittel recognized early on the interest of applying this strain dynamically to induce magnetic resonance [1]. His ideas have seen a recent revival  of interest when combined to a wide range of optical or electrical acoustic wave excitation techniques. These waves are widely used in the fields of semiconductors physics, nanophotonics, and quantum optomechanics. In the Gigahertz range, they become relevant to magnetism physics, as these are typically the eigenfrequencies of the magnetization in most ferromagnets. I will describe the work we have been doing on (Ga,Mn)As using sub-GHz surface acoustic waves (SAWs) to manipulate, control, and switch magnetization - even in the absence of any applied magnetic field [2,3,4]. I will detail the experimental technique we have developed that enables us a spatio-temporal detection of these ultrasound driven magnetization dynamics. I will conclude by some perspectives on the use of magneto-acoustics in both magnetic and acoustic devices.

[1] L. Thevenard et al., “Irreversible magnetization switching using surface acoustic waves,” Phys. Rev. B 87, 144402, 2013.

[2] L. Thevenard et al., “Precessional magnetization switching by a surface acoustic wave,” Phys. Rev. B 93, 134430, 2016.

[3] P. Kuszewski et al., “Resonant magneto-acoustic switching: influence of Rayleigh wave frequency and wavevector,” J. Phys. Condens. Matter  30, 244003, 2018.

[4] P. Kuszewski et al., “Optical probing of Rayleigh wave driven magneto-acoustic resonance,” Phys. Rev. Appl. 10, 034036, 2018.

Laura THEVENARD: She did her PhD on the dilute magnetic semiconductor GaMnAs at the Laboratoire de Photonique et Nanostructures with Aristide Lemaître on (Ga,Mn)As. She then went on to do a post-doc on Permalloy nanostructures in the group of Russel Cowburn, who was then located within Imperial College London. A few years after arriving at Institut of Nanosciences of Paris in 2009 (Sorbonne Universités campus) as a CNRS researcher, she developed with C. Gourdon, colleagues from the lab's Acoustics team, and A. Lemaître from the C2N,  an original strategy to manipulate, control, and switch magnetization using surface acoustic waves of up to 1 GHz. The main experimental techniques are based on the magneto-optical kerr effect, that we implement either statically to perform magnetic domain imaging, or on a "pump-probe" set-up to access magnetization dynamics. In 2015 she received the Bronze Medal of the CNRS.

Seminars

Self-assembled metal organic materials have great potential for optoelectronic applications due to their atomic and structural tunability. While a vast library of these materials has been studied, understanding optoelectronic properties to drive synthesis has been nearly impossible due to their complex structure. Here we consider the self-assembled layered bulk silver benzeneselenolate, [AgSePh]∞, as a representative of a class of coordination polymers exhibiting quantum well characteristics. Using ab initio density functional theory (DFT) and GW and Bethe-Salpeter equation (BSE) approach calculations, we predict and experimentally confirm two-dimensional (2D)-like excitonic and optoelectronic properties in the bulk phase arising from the quantum-confined charge carriers, including large exciton binding energies (~380 meV) and anisotropic absorption and emission. Our study demonstrates how integrating theory and experiment can elucidate general features in hybrid chalcogenide materials scalable via supramolecular chemistry with strong excitonic effects in the presence of anisotropic screening and strong confinement.

Figure 1. I, Material molecular representation with visualization of the predicted excitonic resonances. II, Experimentally measured strong absorption anisotropy. III, Experimentally observed anisotropic excitonic photoluminescence

Lorenzo Maserati Dr. Lorenzo Maserati graduated from Politecnico di Milano with a BSc (2007) and MSc (2009) in Physics Engineering. He obtained his PhD in Nanosciences from University of Genoa (IIT, 2014) with a thesis on colloidal nanocrystal films for optoelectronic applications. Then he joined the Lawrence Berkeley National Lab (LBNL) where he developed metal-organic frameworks membranes for gas separation. In a second postdoctoral appointment at LBNL, he focused his work on the excitonic properties of 2D and 2D-like materials, investigated by ultrafast spectroscopy. Dr. Maserati is currently Researcher at CNST (IIT) in Milan where he studies self-assembled metal-organic chalcogenides for optoelectronic applications. His interests range from materials chemistry to solid state and device physics. He is recipient of the “NanoInnovators’s got talent” award (Rome, 2016), and the Marie-Curie Seal of Excellence (2017).

Seminars

     In the last years, soft chemical synthetic methods opened the path to create highly tunable thin film architectures, with complex yet controlled structure at different length scales. Optical nanosystems “decorated” with molecular, biological or nanoscale functions precisely located in space can be pre-designed and produced through the production and controlled assembly of nanobuilding blocks. In particular, Mesoporous Thin Films (MTF) are interesting for their tailorable optical, electronic or catalytic properties, and their compatibility with the requirements of electronics and optics industry. Each MTF is in turn a building block for more complex architectures with synergic properties derived from the control of the spatial location of well-controlled components.

We will present MTF architectures with programmable optical properties, in particular Mesoporous Photonic Crystals (MPC) and Nanoparticle-Mesoporous Nanocomposites (NMNC). These materials permit to harness and couple chemical and surface properties with photonic and plasmonic features of the ensemble. We can design and build stimuli-responsive autonomous systems that transduce chemical signals to optical response through information encoded in their structure at the molecular, mesoscopic or microscopic levels. The combination of the photonic and plasmonic properties of MPC and NMNC permits to exploit light confinement or amplification. These responsive nanosystems present applications in SERS, Tamm-based sensors, optical waveguides or photocatalysts.

Galo Soler-Illia studied Chemistry in the University of Buenos Aires, and performed a postdoc at UPMC, Paris. He is the Dean of Instituto de Nanosistemas at Universidad Nacional de San Martin, CONICET Principal Researcher, Associate Professor at the University of Buenos Aires, and Full Member of the National Academy of Exact and Natural Sciences of Argentina. He designs and produces intelligent nanosystems using chemical methods inspired by nature. He has published more than 160 papers in reviewed journals, with 13.000+ citations (h=45), and filed four patents.

Seminars

After the bronze Antikythera calculator (200 BC), the B. Pascal wooden calculating clock (1642 AC) and the micro-fabricated machineries on a silicon surface (middle of the 1980’s), it is now foreseen to miniaturise mechanical machineries down to the size of a single molecule.

We will present our molecular design and experiments starting from the random rotation of a single molecule-wheel [1] and the step by step controlled rotation of a single molecule gear 1.2 nm in diameter [2]. More complex molecular machineries will be presented like a rack & pinion mechanism [3], a molecule wheelbarrow [4] and a train of molecule-gears. To drive molecule-machineries, we are using the mechanical interaction with the tip apex end atom of an STM and/or the inelastic tunnel current effect as exemplify with our step by step controlled molecule-rotor [5]. In the prospect to measure the motive power of a single molecule [6] and to interconnect mechanically a single molecule to the mesoscale, nano-fabrication of solid state nano-gears down to 30 nm in diameter will be presented [7]. We will end by a little survey of the April 2017 1st International Nanocar race [8,9] and by announcing Nanocar race II under the European project MEMO (Mechanics with Molecule(s)) for 2021.

References

 [1] J.K. Gimsewski, C. Joachim, V. Langlais, H. Tang & J. Johanson, Science, 281, 531 (1998)

 [2] C. Manzano, W.H. Soe, F. Ample, A. Gourdon & C. Joachim, Nature Mat., 8, 576 (2009)

 [3] F. Chiaravalloti, A. Gourdon, C. Joachim & F. Moresco, Nature Mat.., 6, 30 (2007).

 [4] C. Joachim, H. Tang, F. Moresco, G. Rapenne & G. Meyer, Nanotechnology,13, 330 (2002).

 [5] U.G.E. Perera, F. Ample, H. Kersell, Y. Zhang, G. Vives, J. Echeverria, M. Grisolia,

    G. Rapenne, C. Joachim and S.-W. Hla, Nature Nanotech., 8, 46 (2013).  

 [6] R. Ohmann, J. Meyer, A. Nickel, J. Echevaria, C. Joachim, F. Moresco and G. Cuniberti,

    ACS Nano, 9, 8394 (2015)

 [7] Deng Jie, C. Troadec, F. Ample & C. Joachim, Nanotechnology, 22, 275307 (2011).

 [8] C.Joachim and G. Rapenne, ACS Nano, 7, 11 (2013).

 [9] G. Rapenne and C.Joachim, Nature Rev. Mat. 2, 17040 (2017).