Quantum Nanoelectronics Seminars

All the "Quantum Nanoelectronics Seminars" past and future in this section.

The next seminar will be held on :
Tuesday 11 July 2017 at 2pm
Room Rémy Lemaire - Institut Néel
Mandatory registration


Shaffique Adam (National University of Singapore)
The role of electron-electron interactions in graphene

About ten years ago, a new electronic material appeared – notable not only for its ease of preparation and theoretical simplicity, but also by its promise for future electronic devices. Single monatomic sheets of carbon, known as graphene, are described as weakly interacting massless Dirac fermions and in many ways, are a textbook system to test physical models. In this talk, I will begin by briefly reviewing the theory for graphene at the Dirac point where competing effects of disorder, electron-electron interactions, and quantum interference conspire together to give a surprisingly robust state whose properties can be described using a weakly-interacting semi-classical picture [1]. Motivated by some recent experiments in ultra-clean graphene, we use a combination of nonperturbative numerical and analytical techniques that incorporate both the contact and long-range parts of the Coulomb interaction to address the role of electron-electron interactions at the Dirac point in the absence of disorder. We show that without strain, graphene remains metallic. But that a rather large – but experimentally realistic – uniform and isotropic strain provides a promising route to make graphene an antiferromagnetic Mott insulator [2]. Finally, we address the interaction enhancement of the Fermi velocity. Using quantum Monte-Carlo simulations with a long-range Coulomb tail, we identify the two previously discussed regimes : a Gross-Neveu transition to a strongly correlated Mott insulator, and a semi-metallic state with a logarithmically diverging Fermi velocity accurately described by the random phase approximation. Most interestingly, experimental realizations of Dirac fermions span the crossover between these two regimes providing the physical mechanism that masks this velocity divergence. We explain several long-standing mysteries including why the observed Fermi velocity in graphene is consistently about 20 percent larger than the best values calculated using ab initio and why graphene on different substrates show different behavior [3].

[1] S. Das Sarma, S. Adam, E. H. Hwang, and E. Rossi, “Electronic transport in two dimensional graphene”, Rev. Mod. Phys. 83, 407 (2011).

[2] H. Tang, E. Laksono, J.N.B. Rodrigues, P. Sengupta, F.F. Assaad, and S. Adam, "Interaction driven metal-insulator transition in strained graphene", Phys. Rev. Lett. 115, 186602 (2015) ;

[3] H. Tang, J.N. Leaw, J.N.B. Rodrigues, I. F. Herbut, P. Sengupta, F.F. Assaad, and S. Adam, "The role of electron-electron interactions in graphene", Submitted (2017).

Contact : Shaffique Adam

The organisation committee,
M. Hocevar, B. Sacepe, R. Whitney, C. Groth

If you want to plan invitations, please contact us at the following address :
equipe-seminaires-nano@fondation-nanosciences.fr

Upcoming

Past
11 juillet 2017
Charge quantum interference device on superconducting nano-wiresby Oleg Astafiev (Royal Holloway, University of London)
13 june 2017
Evolving functionality in nanomaterial networks by Wilfred G. van der Wiel (University of Twente, The Netherlands)
6 june 2017
Relaxation of an Electron Spin in a Moving Quantum Dotby Xuedong Hu (Department of Physics, University at Buffalo, USA)
30 may 2017
Understanding and exploiting interactions between components in quantum circuits by Philippe Joyez (SPEC, CEA-Saclay)
22 may 2017
Feedback-tuned high fidelity gates for (GaAs based) two-electron spin qubits by Hendrik Bluhm (RWTH Aachen University, Germany)
16 may 2017
Electron teleportation in multi-terminal Majorana islands : Kondo effect at high temperature by Karen Michaeli (Weizmann Institute for Science, Israel)
9 may 2017
Superconducting Atom Chips by Rainer Dumke (Nanyang Technological University, Singapore)
4 may 2017
Quantum Physics in One Dimension using Nanostructured Josephson-junction Arrays by Tim Duty (University of New South Wales, Sydney)
20 april 2017
Les bits quantiques MOS by Prof. Michel Pioro-Ladrière (Professeur associé, Département de physique, Université de Sherbrooke et Directeur adjoint, Institut Quantique, Université de Sherbrooke)
11 april 2017
Quantum microwave devices based on inelastic Cooper pair tunneling by Max Hofheinz (CEA INAC)
28 march 2017
Spin to charge conversion at room temperature using spin orbit coupling and recently discovered topological insulators by Laurent Vila (SPINTEC)
21 march 2017
Spin Dynamics in Out-of-Equilibrium Superconductors by Charis Quay (Laboratoires de Physique des Solides, Université Paris Sud)
14 march 2017
From CMOS transistors to CMOS spin qubits by Marc Sanquer (INAC/PHELIQS/LATEQS CEA & UGA)
14 february 2017
Quantized circular photogalvanic effect in Weyl semimetals by Adolfo Grushin (Department of Physics, UC Berkeley et Institut Néel, CNRS & UGA)
7 february 2017
Confining the state of light to a quantum manifold by engineered two-photon loss by Zaki Leghtas (Laboratoire Pierre Aigrain - Ecole Normale Supérieure)
31 january 2017
Many-Body Localization Basics - Recent Highlights - Experimental possibilities by Nicolas Laflorencie (Laboratoire de Physique Théorique, Toulouse)
24 january 2017
Fluctuation theorems in engineered environments by Marcelo F. Santos (Universidade Federal do Rio de Janeiro, Brazil)
17 january 2017
THz Spectroscopy on Disordered Superconductors and the “Superconducting Dome” of Granular Aluminum by Marc Scheffler (Physikalisches Institut, University of Stuttgart, Germany)
10 january 2017
Mesoscopic Spectroscopy with Josephson Junctions by Caglar GIRIT (Collège de France, Paris)
13 december 2016
Ultrastrong light-matter with propagating photons by Juan José García Ripoll (Institute of Fundamental Physics, Spain)
10 november 2016
Exciton states mixing and second harmonics generation in transition metal dichalcogenide monolayers by Mikhail Glazov (Ioffe Institute, Russie)
11 october 2016
Quantum Phase Slips and Voltage Fluctuations by Andrei D. Zaikin (Karlsruhe Institute of Technology (KIT), Germany)
4 october 2016
2D solids : optical spectroscopies and nano-optomechanics by Antoine Reserbat-Plantey (ICFO Barcelone)

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juillet 2017 | septembre 2017