Modeling silicon-on-insulator quantum bit arrays
A post-doctoral position is open at the Interdisciplinary Research Institute of Grenoble (IRIG, formerly INAC) of the CEA Grenoble (France) on the theory and modeling of arrays of silicon-on-insulator quantum bits (SOI qubits). This position fits into an ERC Synergy project, quCube, aimed at developing two-dimensional arrays of such qubits. The selected candidate is expected to start between October and December 2019, for up to three years.
Many aspects of the physics of silicon qubits are still poorly understood, so that it is essential to support the experimental activity with state-of-the-art modeling. For that purpose, CEA is actively developing the “TB_Sim” code. TB_Sim relies on atomistic tight-binding and multi-bands k.p descriptions of the electronic structure of materials and includes, in particular, a time-dependent configuration interaction solver for the dynamics of interacting qubits.
The aims of this post-doctoral position are to improve our understanding of the physics of these devices and optimize their design, and, in particular,
- to model spin manipulation, readout, and coherence in one- and two-dimensional arrays of SOI qubits.
- to model exchange interactions in these arrays and assess the operation of multi-qubit gates.
The candidate will have the opportunity to interact with the experimental teams from CEA/IRIG, CEA/LETI and CNRS/Néel involved in quCube, and will have access to data on state-of-the-art devices.
Spectroscopy of AlN colored centers
The study of QD-like emission from deep emission centers in semiconductor has become an important topic in the general framework of quantum information processing and nanoscale sensing, the emblematic emission center being the N-V defect in diamonds. Recently, research has been conducted to evaluate the potential of other defects in various materials, for instance in GaN and BN. Oddly, not much is known on color centers in AlN, despite the many assets of this material : it can be epitaxially deposited, high quality bulk substrates are available, it can be processed as high quality factor microcavities.
We propose in this 12 months post-doc to explore the optical properties of deep luminescing centers in AlN. We will study by microphotoluminescence (either cw or time-resolved) various types of AlN : thin AlN grown on Si (possibly processed as membranes), thick AlN grown on sapphire, ensembles and single AlN nanowires.
Nano-silicon/graphene composites for high energy density lithium-ion batteries
This postdoctoral fellowship is part of the Graphene Flagship Core 2 H2020 european project (2018-2020) on the energy storage applications of graphene. In lithium-ion batteries, graphene associated to nanostructured silicon in a proper composite helps increase the energy capacity. Indeed graphene wraps silicon, reducing its reactivity with electrolyte and the formation of the SEI passivation layer. It also maintains a high electrical conductivity within the electrode.
The study will compare two technologies: graphene-silicon nanoparticles and graphene-silicon nanowires. The former composite, already explored in the above mentioned project, will be optimized in the present study. The latter is a new kind of composite, using a large scale silicon nanowire synthesis process recently patented in the lab. The postdoc will work within two laboratories: a technological research lab (LITEN) with expertise in batteries for transportation, and a fundamental research lab (INAC) with expertise in nanomaterial synthesis.
The postdoc will synthesize silicon nanowires for his/her composites at INAC. Following LITEN know-how, she/he will be in charge of composite formulation, battery fabrication and electrochemical cycling. He/she will systematically compare the electrochemical behavior of the nanoparticle and nanowire based silicon-graphene composites. Comparison will extend to the mechanism of capacity fading and SEI formation, thanks to the characterization means available at CEA Grenoble and in the European consortium: X-ray diffraction, electronic microscopy, XPS, FTIR, NMR spectroscopies. She/he will report her/his work within the international consortium (Cambride UK, Genova Italy, Graz Austria) meetings.
A 2-year post-doctoral position is open.
PhD in materials science is requested. Experience in nanocharacterization, nanochemistry and/or electrochemistry is welcome.
Applications are expected before May 31st, 2018.
In situ synchrotron X-ray monitoring of the growth of defect-free two-dimensional materials by liquid-metal catalytic routes
The postdoctoral research project is part of a four-year European FET-Open project called LMCat (http://lmcat.eu/) bringing together five European labs, including the ESRF and the CEA-INAC, to develop the growth of defect-free two-dimensional materials by liquid-metal catalytic routes. A central lab will be established at the ESRF to develop an instrumentation/methodology capable of studying the ongoing chemical reactions on the molten catalyst. The growth by chemical vapor deposition at high pressure and temperatures will be characterized in situ, by means of two main techniques: Raman and X-ray scattering (Grazing Incidence X-Ray Scattering and Reflectivity). It will be complemented by theoretical calculations performed in Munich. The successful candidate will be in charge; together with a PhD student, of the in situ synchrotron X-ray scattering measurements, using the ESRF ID10 liquid scattering beamline (http://www.esrf.eu/UsersAndScience/Experiments/CBS/ID10) and the P08 beamline of PETRA-III (photon-science.desy.de/facilities/petra_iii/beamlines/p08_highres_diffraction/index_eng.html), in Desy.
You should hold a PhD in physics, chemistry or material science or closely related science. Previous experience of complex instrumental environment, MBE or CVD growth methods and / or with synchrotron X-ray scattering / diffraction / reflectivity, especially on liquids, will be an advantage. You should be motivated to work with an international team of young researchers with an experimental setup at the forefront of instrumental development, and ready to travel in Germany (Hambourg) for extended periods to perform some of the experiments. A good practice of English is mandatory. You should also have:
This is a full time, 3 year contract.
Please submit a 1 page cover letter stating the motivation, research experience and goals, ; a curriculum vitae, and contact information for 3 references.
Modeling silicon-on-insulator quantum bits
Quantum information technologies on silicon have raised an increasing interest over the last five years. CEA is pushing forward its own original platform based on the “silicon-on-insulator” (SOI) technology. The information is stored in the spin of carrier(s) trapped in quantum dots, which are etched in a thin silicon film and are controlled by metal gates. SOI has many assets: the patterning of the thin film can produce smaller, hence more scalable qubits; also, the use of the silicon substrate beneath as a back gate provides extra control over the quantum bits (qubits).
Many aspects of the physics of silicon spin qubits are still poorly understood. It is, therefore, essential to complement the experimental activity with state-of-the-art modeling. For that purpose, CEA is actively developing the "TB_Sim" code. The aims of this 2-year post-doctoral position are to model spin manipulation and readout in SOI qubits, and to model decoherence and relaxation at the atomistic scale using TB_Sim. This modeling work will be strongly coupled to the experimental activity in Grenoble. The candidate will have access to experimental data on state-of-the-art devices.