Anastasia Varlet - ESR7
Anastasia will study spin properties of graphene quantum dots in electron transport experiments in parallel and perpendicular magnetic fields.
email address – email@example.com
Host organisation (principal node)
ROLE WITHIN S3NANO
Electronic transport in gate-defined graphene nanostructures.
This project will focus on the realization of gate-defined graphene nanostructures.
One of the criteria for quantum information processing is to have long coherence time of the considered qubit system. Graphene is therefore expected to be a promising candidate for the realization of spin qubit: being a carbon-based material, its spin coherence time is expected to be long (because of weak spin-orbit coupling and hyperfine interaction) .
The realization of graphene spin qubits requires high quality quantum dots. However getting high quality graphene is challenging. It exhibits a non-negligible disorder, which is mainly due to the environment (substrate and adsorbates). As suspended nanostructures are mechanically unstable, an atomically flat and charge-trap-free substrate such as hexagonal boron nitride  is needed to fabricate clean graphene devices by exfoliation.
Another way to improve graphene quality is to find a way to isolate the island without any etching. Bilayer graphene is a solution: by applying an electric field perpendicularly to the bilayer sheet, a band gap can be open [3,4]. This way, nanostructures can be in principle defined via gating, just as it is done with GaAs/AlGaAs quantum dots.
Such gate-defined quantum dots have already been achieved with suspended bilayer graphene , and also recently with encapsulated bilayer graphene (bilayer sandwiched between two BN flakes) . But the access to the "clean" excitation spectrum of these charged islands as well as reaching the few electron regime remain challenging.
 B. Trauzettel, D.V. Bulaev, D. Loss and G. Burkard, Spin qubits in graphene quantum dots, Nature Physics 3, 192 - 196 (2007)
 C. R. Dean, A. F. Young et al., Boron nitride substrates for high-quality graphene electronics , Nature Nanotechnology 5, 722–726 (2010)
 E. McCann, Asymmetry gap in the electronic band structure of bilayer graphen", Phys. Rev. B 74, 161403(R) (2006)
 S. Dröscher, C. Barraud, K. Watanabe, T. Taniguchi, T. Ihn, K. Ensslin, Electron flow in split-gated bilayer graphene, arXiv:1207.4942 (2012)
 M. T. Allen, J. Martin, A. Yacoby, Gate-defined quantum confinement in suspended bilayer graphene, Nature Communications 3, 934 (2012).
 A. M. Goossens, S. C. M. Driessen, T. A. Baart, K. Watanabe, T. Taniguchi, L. M. K. Vandersypen, Gate-Defined Confinement in Bilayer Graphene-Hexagonal Boron Nitride Hybrid Devices, Nano Lett., Article ASAP
EMPLOYMENT AND TRAINING
Since October 2011
ETH Zürich - Nanophysics Group (Prof. Dr. K. Ensslin - www.nanophys.ethz.ch) - Graphene Team:
Gate-defined nanostructures on BN/Bilayer Graphene/BN heterostructures.
2011 - (5 months)
CNRS – Néel Institute - Grenoble – Nanospintronics and molecular transport group (Dr. W. Wernsdorfer):
Transport in single-molecule magnet-based transistors.
Supervisor: Dr. Franck Balestro
2010 - (10 weeks)
Max Planck Institute for Solid State Research – Von Klitzing Department - MBE Group (Prof. Dr. W. Dietsche) Stuttgart, Germany: work on the role of parallel conduction in GaAs/AlGaAs heterostructures.
Supervisor: Dr. Stefan Schmult
2009 - (1 month)
The sales administration of the company JKR Consulting (telecommunications company): customers and stocks management and commercial experience (phone and physical prospecting).
EDUCATION AND QUALIFICATIONS
- 3rd grade in the engineering school called PHELMA (Physics, Electronics, Materials - phelma.grenoble-inp.fr/ ) - Grenoble, France. Specialized in Physics and Nanosciences.
- Double Master Diploma in parallel: Research Master N2 (Nanosciences, Nanotechnologies, speciality « Nanophysics-Nanostructures »).
2nd year in PHELMA – section Physics and Nanosciences.
Research Project: studying and modelling of new reeds for musical instruments.
1st year in PHELMA – section Physics, Electronics and Telecom.
Project: studying and modelling of a solar tower.
2006 – 2008
Preparatory Classes (specialized in Mathematics and Physics). Lycée Thiers - Marseille,
Baccalauréat, scientific section = A-level passed with honors (score > 80%).
RESEARCH INTERESTS - Quantum Transport, Magnetism, Quantum information, Spin physics.
SPECIAL SOFTWARES - MatLab, LabView.
FABRICATION TECHNIQUES - E-Beam lithography, photolithography, RIE, electron beam physical vapor deposition, Atomic Layer Deposition, Scanning Electron Microscopy, Atomic Force Microscopy, electromigration.
EXPERIMENTAL TECHNIQUES - Low temperature measurements (4K to 10mK), under magnetic field (up to 10T).
FRENCH - Mother tongue.
ENGLISH - Since 2001: written, spoken and read fluently. TOEFL graduated.
GERMAN - Since 1999: advanced level (2 stays in German families + 10 weeks internship in summer 2010 + PhD work in German-speaking Switzerland