Created in 2009, The Nanosciences Foundation Thesis Prize reward every year the best 2 thesis defended on nanosciences and prepared in one of the 33 associated laboratory.
During the thesis Prize award ceremony, the winners are invited to present their research to a heterogeneous audience. Recipients of scientific prestigious prizes are invited to participate to the ceremony too.
This year, the ceremony took place on Monday, January 23 at Lecture room - CNRS site (invitation only, registration mandatory).
Winners of the Nanosciences Foundation’s Thesis Prize
Semiconducting nanowires offer the possibility to fabricate extremely high quality light-emitting structures for a wide range of applications, ranging from photovoltaics and optoelectronic displays to solid-state based sources of quantum light. However, because of their small size, studying and engineering their optical properties is a challenging task. Metallic nanostructures, on the other hand, provide the ability to control electromagnetic fields at length scales well below the wavelength. In his thesis, Mathieu developed a set of nanocharacterization techniques to correlate various measurements on the one and same nanowire, allowing a full characterization of its optical and electronic properties. He implemented a novel nanofabrication technique to couple single quantum dots embedded in semiconducting nanowires to metallic nanostructures, enhancing their light emission properties.
Mathieu is currently working as a post-doctoral researcher at the Paris-Diderot University, where he is developing metamaterial-based ultra-sensitive infrared photodetectors.
Quantum transport experiments have advanced tremendously in particular with the development of nanostructured quantum point contact (QPC) which is a gate-defined narrow and short constriction to confine electron transport in two-dimensional electron gases of semiconductor heterostructures. In the quantum Hall (QH) regime at high magnetic fields, the QPC allows to regulate the exact number of electron channels transmitted through the constriction between the two electronic reservoirs leading to a precise conductance quantization. In this thesis, we achieved successfully to combine a QPC with high-mobility graphene which has represented a major challenge so far due to the gapless electronic band structure of graphene. For this purpose, we also derived a process to produce high-quality graphene. This paves the way for a broad range of new experiments that probe the integer and fractional QH regimes in graphene.
Katrin is currently working as a patent examiner at the European Patent Office in The Hague.
Innovations with Gallium Nitride (GaN) revolutionized the global lighting industry (LEDs) and improved data storage and reading techniques (Blue Ray) to a degree worthy of a Nobel Prize (2015).
By using GaN in a heterojunction (two materials), the quantum mechanical effects of electrons in this system come to life, and can be used to create “intersubband” devices dependent on transitions between these quantized states. These devices cover the invisible infrared spectral region and can lead to advances in thermal cameras, security scanners, telecommunications networks, and even medical diagnostics. This thesis pushed these devices towards “forbidden” wavelengths and created never-before-seen devices by using cutting-edge nanomaterial growth techniques and quantum engineering.
Mark is currently working at L-3 WESCAM in Canada, designing the next generation of electro-optical systems (lasers, cameras, detectors, etc.) for use in their eye-in-the-sky turrets.
David Van Zanten
Accurate control over the state and motion of single individual electrons would enable a variety of appealing applications reaching from quantized to quantum coherent electron sources. A promising candidate, foreseen to meet the demand, combines the concept of quantized charge in single electron transistors and the gapped density of states in superconducting metals. Inspired by this ingenious application and the advances in quantum dot transport, we explore the operation of a hybrid electron turnstile embodying a bottom-up quantum dot.
The devices are obtained by controlled electromigration of aluminium nano-wires preceded by the deposition of gold nano-particles. We obtain a quantized current up to 200 MHz. In the low frequency regime (below 60 MHz) we observe a systematic current suppression. Supported by theoretical work, we show that the underlying missed tunnel events are caused by adiabatic traverses across the avoided crossing of a quantum dot level and superconducting gap edges, which demonstrates coherent control over the electronic wavefunction.
Arnaud is presently working as a post-doctoral researcher at the University of Tokyo in the group of Yasunobu Nakamura, where he is focused on converting microwave photons to optical photons in the context of quantum engineering in the perspective of enabling long-distance communications between superconducting quantum computers.
Benoit is currently working at the U.S. National Institute of Standards and Technology. He develops numerical and analytic models to describe the response of polycrystalline photovoltaic materials to incident energy from photons, electrons, and bias potentials.
Presently, Manan is working as an Assistant Professor in the department of Electrical Engineering at Indian Institute of Technology - Delhi (IIT-D). He is also developing an early-stage startup focussing on neuromorphic/machine-learning systems and solutions…
Stefan is currently working at Sensirion AG, an environmental sensor company. As member of the sensor innovation team, he develops new sensors, which are able to monitor various environmental parameters. Their components are used in the automotive industry, medical technology, building technology, and in consumer goods with the purpose to make devices more accurate and efficient, with better performance and less energy consumption.
Jing is currently working in Global Foundries in New York as senior engineer in process integration. His current work focuses on the research and development of fabrication process for advanced planar MOSFET and FinFET.
Sylvain is currently in a postodctoral position in the Biophotonics group of the university of Geneva. His research steerd towards the study of quantum coherence effects in biological systems (typically the kind of systems for the modelisation of which quantum simulators will be very welcome!).He more specifically works on optical diagnostics methodsusing such coherent effects.
Actin networks are one of those fabulous self-organized biopolymers that sustain cell architecture while those perform highly complex mechanical transformations in order to achieve efficient morphogenesis, cell motility or any cell shape changes. Perpetual dynamics, organization, regulation or rapid reconstruction are only a few of the properties required for these morphological features which are supported by the actin cytoskeleton.
During her thesis, she has developed different projects in order to tackle the problem of actin network dynamics and organization as well as the molecular mechanism at the origin of force production in biomimetic reconstituted systems. Stepping aside from the conventional actin based particles’ motility studies, one of the major innovations was to generate highly ordered auto-assembled actin motifs, finely tuned by the reproducible spatial control of actin nucleation sites by micropatterning. Moreover the presence of molecular motors, such as myosin, on these controlled systems allowed us to reproduce some of the cellular biomechanical processes of tension and contractility. A direct visualization of filaments demonstrates a spectacular myosin-induced actin network deformation and disassembly that depend on the original network architecture. Following an “orientation selection” mechanism such phenomenon could therefore play an essential role in the spatial regulation and scalability of expanding and contracting regions of actin cytoskeleton in cells.
Ioan Mihai Pop
The central result of my thesis is the observation of quantum phase-slips in Josephson junction networks. A phase slip is associated with the passage of a magnetic quasi-particle (a “fluxon”) through a Josephson junction chain.
His team has observed the quantum interference of phase slips, an effect predicted by Y. Aharonov and A. Casher in 1984. This is the electromagnetic dual of the well-known Aharonov-Bohm effect.
They have also demonstrated that a chain of Josephson junctions, which is a complex
mesoscopic object, can accurately be treated as a single quantum object, with few degrees of freedom. These results open the way for a wide range of possible uses of quantum phase-slips in the design of novel Josephson junction circuits, such as topologically protected qubits, frequencyto-current conversion devices or quantum simulators.
The implementation of electronic functionalities originating from the control of a single charge in silicon CMOS devices has been a challenge for years. Using top-down nanofabrication techniques, they fabricate extremely small transistors on silicon-on-insulator wafers. At low temperature, the electrical conduction of these nano-FETs is dominated by electron tunneling and singleelectron effects. Their measurements reveal that electrons tunnel through the orbitals of individual dopants, randomly distributed in the channel of the devices.
By focusing on short transistors, they find devices in which only a single dopant determines the drain-source current, thus forming a single-dopant transistor. The dopant dramatically alters the electrical characteristics up to room temperature, which is observed mainly through an enhancement of the sub-threshold current and increased variability.
The thesis work focused on the use of carbon nanotubes (CNTs) and/or electrogenerated polymers in biosensors or bio-fuel cells to increase performances of this kind of devices (stability, sensitivity…). Electrogenarated poly(pyrrole-nitriloacetic acid) was used with its affinity partner, histidine, to immobilize DNA-probes tagged with histidines. Thanks to a label-free detection of the DNA-target by electrochemical impedance spectroscopy, the lowest detection limit described in the literature was reached (10-15 mol L-1). Following this, an innovative and original concept for the immobilization of biotine-tagged biomolecules onto this polymer was studied and illustrated using different biotinylated biomolecules (enzymes and DNA). CNTs were used to elaborate 3D architectures based on non-covalent functionalization of this material. Multiple functionalization of single walled CNTs (SWCNTs) by π-π stacking was achieved with modified pyrenes using the three most common affinity systems. Then, a hydrogenase was connected on hybrid materials based on redox polymer/CNTs in order to produce clean energy from H2.
The aim of molecular spintronics is to gather the specific tools, both experimen-tal and theoretical, of different themes: from molecular magnetism, to spintronic and molecular electronic.
In order to implement this project, we had first to create a transistor in which the central part is a single mole-cule. This was achieved through the use of the elec-tromigration technique, a difficult choice as implemented in a dilution cryostat.
Through experiments with fullerene molecules, also known as C60, we have studied the electronic interac-tions between a nano-sized object and metallic elec-trodes. Combining very low temperatures and molecular properties (degenerate electronic levels, high charging energy) allowed us to observe a quantum phase transi-tion between two magnetic states with different symme-tries. We also provided strong experimental evidences for the observation of an under-screened Kondo effect.
Spin transfer torque has attracted much attention as an alternative to magnetic field to manipulate magnetization of nanometric ferromagnetic objects.
In magnetoresistive structures, spin-polarized current can trigger an auto-oscillation of the magnetization with frequency in the gigahertz range. Such structures, called spin torque oscillators (STO), are very promising for integrated microwave sources because of their nanometric size and large tunable frequency range.
In this work, current-induced magnetization dynamics has been investigated in spin valves and magnetic tun-nel junctions using frequency and time-domain analy-ses. The possibility to induce coherent large amplitude magnetic excitations has been demonstrated and ex-perimental results have been compared to numerical models, thus providing a better understanding on how to improve STO performances.
Graphene is one of the rising materials in condensed matter physics because of its outstanding electronic and transport properties.
The thesis work is focused on epitaxial graphene where the annealing of a SiC surface leads to the formation of few graphitic layers. Eventhough the system consists in several C layer on a SiC substrate, transport measurements evidence prop-erties expected for an isolated graphene sheet. The question then is how the conducting graphene layer can be decoupled from its neighbourhood (substrate and other C layers). To address this issue, atomic and electronic structures of graphene on both surfaces of SiC (Si- and C-face, respectively) have been studied by ab initio calculations and compared to Scanning Tunnel-ing Microscopy images (STM).