"Quantum Nanoelectronics" Seminars in 2010 - Nanosciences

Séminaires Nanoelectronique quantique

"Quantum Nanoelectronics" Seminars in 2010

Interaction effects on noise in nanojunctions

Tuesday 14 December 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Tomáš NOVOTNÝ (University Charles - Prague, Czech Republic) In my talk I will present some aspects of current noise studies in interacting nanostructures largely motivated by undergoing experimental works. After the introduction of the charge counting...

A single silicon dangling bond: deep insight into a quantum system

Tuesday 7 December 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Christophe DELERUE (IEMN, Lille) The objective of the lecture is to review experimental and theoretical works realized at IEMN over several years on a prototypical defect at the surface of a semiconductor: a dangling bond at the Si(111) surface. We show that this defect gives rise to a deep level in the gap which represents a...

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Tuesday 30 November 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Thierry DEUTSCH (CEA-INAC/SP2M/L SIM)

Phase cooling

Tuesday 23 November 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Marco APRILI (LPS Orsay) The radiation pressure is used for cooling atoms, ions and optomechanical devices. In a Fabry-Pérot interferometer in which one of the two mirrors vibrates, the Brownian motion of the vibrating mirror and hence its effective temperature can surprisingly be lowered by increasing...

A multilevel nanowire technology

Tuesday 16 November 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Thomas ERNST (CEA-Leti, Grenoble) 3D CMOS nanowire matrices and 2D thin film technologies recently developed enable not only sub-22nm CMOS device scaling but also ultimate co-integration of novel functionalities [1-3]. For CMOS scaling, Silicon-On-Insulator (SOI) or innovative...

Dynamics in strongly correlated ultracold gases

Tuesday 9 November 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Corinna KOLLATH (Ecole Polytechnique, Palaiseau) Atomic gases cooled to Nanokelvin temperatures are a new exciting tool to study a broad range of quantum phenomena. In particular, the outstanding degree of control which has been achieved over these quantum systems facilitates access to the dynamics of strongly correlated quantum many body...

Spin-orbit qubits in InAs nanowires

Tuesday 02 November 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Stevan NADJ-PERGE (Delf University of Technology, Netherlands) Spin-orbit interaction couples spin and orbital degree of freedom. Transitions between spin-orbit eigenstates in quantum dots can be induced by electric fields. We demonstrate spin-orbit qubits defined in an InAs nanowire, a material with strong spin-orbit...

Tunneling spectroscopy of individual Andreev Bound States in a carbon nanotube

Tuesday 12 October 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Philippe JOYEZ (Groupe Quantronique, Service de Physique de l'Etat Condensé, CEA Saclay) Many experiments have demonstrated that when non-superconducting nanostructures such as nanotubes, nanowires, ferromagnet, molecules, etc. are connected to superconducting electrodes, they can nevertheless sustain a supercurrent. In spite of the...

Theory of supercurrent in microwave-irradiated quantum point contacts

Tuesday 5 October 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Sebastian BERGERET (University of San Sebastian) In recent years, the dc Josephson effect has been observed in a great variety of weak links such as those based on atomic contacts, carbon nanotubes, semiconductor nanowires and graphene. In spite of their intrinsic differences, the dc Josephson effect in these systems...

Enhancing the Proximity Effect in Superconductor / Ferromagnet Devices

Tuesday 28 September 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Jason ROBINSON (University of Cambridge, UK) In a ferromagnet which is coupled to a superconductor, a spin-singlet supercurrent can exist but will rapidly decay over a few nanometers [1, 2]. Enhancements to this proximity effect are predicted to occur in more exotic systems in which some inhomogeneous magnetism is present [3]. In such...

Coherence properties of two-level-systems in superconducting phase qubits

Tuesday 14 September 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Jürgen LISENFELD (University of Karlsruhe, Germany) Over the past decade, it became possible to operate superconducting electrical circuits in the coherent quantum regime, and these circuits show great promise to be used as quantum bits (qubits) in a solid-state quantum computer. In this talk, the so-called phase qubit will be introduced. It is...

Fluctuation relations in mesoscopic transport

Tuesday 7 September 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Alexander ALTLAND (Université de Cologne, Allemagne) In this talk we will discuss the concept of fluctuation relations (FRs) in application to mesoscopic transport. Fluctuation relations are rigorous identities for the non-equilibrium averages of physical observables -- heat, mechanical or electrical work, etc. Starting from microscopic master equations,...

Chirality and fluctuation relations in mesoscopic tranpsort

Tuesday 31st August 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Markus BUTTIKER (University of Geneva, Switzerland) The linear conductance of a two terminal conductor is even under magnetic field reversal and through the Nyquist-Johnson relation connected to the equilibrium current noise. Already the quadratic in voltage term of the current-voltage relation (the second order conductance) is...

Approaching the quantum limit of amplification with Josephson microwave circuits

Tuesday 29 june 2010 at 4pm CNRS, Room "Nevill Mott" (D420) Michel Devoret (Yale, United States et Collège de France, Paris) Quantum Mechanics puts a limit on how small the degradation of information passing through an amplifier can be. It is known theoretically that the minimum noise added by an "op-amp"-like amplifier to the signal amounts at least to half a photon at the signal frequency. Can we develop a practical...

Graphene as an Open Platform for Tuning 2D Electronic Transitions

Tuesday 22 june 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Vincent Bouchiat (Institut Néel, Grenoble) Graphene is a recently realized two-dimensional (2D) crystal with many interesting properties including a band structure that allows the carrier concentration to be tuned continuously between electrons and holes. The easily accessible 2D electron gas in graphene provides an ideal platform on which to...

Adiabatic manipluations of Josephson qubits for quantum computing

Tuesday 15 June 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor LianFu Wei (Southwest Jiaotong University, China) It is well-known that there are two typical appraoches to implement quantum computing; one is the gate-based quantum computing (i.e., implemented by a series of logic gates), and the other is adiabatic computing (i.e., adiabatically manipulating the system from a known initial state to the...

Light and Metal - Fundamentals and Applications of Surface Plasmons -

Tuesday 8 June 2010 at 4pm CNRS Bât A, conference room on 2nd floor Thomas EBBESEN (Institut de Science et d'Ingénierie Supramoléculaires - Strasbourg) Surface plasmons have generated considerable renewed interest in the past decade due to wide potential they offer in everything from sensors to opto-electronics. Using modern fabrication techniques, it is possible to...

From the Aharonov-Bohm effect to Peltier-cooling in mesoscopic devices

Tuesday 25 May 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Robert S Whitney (Institut Laue-Langevin, Grenoble) The electronic transport properties of nanoscale devices at are strongly affected by the quantum coherence of the electrons. However interference effects can also cause finite thermoelectric effects; a heat-difference can induce a voltage-difference (Seebeck effect) and vice-versa...

Superconductor-insulator transition in sub-10 nm nanowires

Tuesday 18th may 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Alexey Bezryadin (University of Illinois) As the diameter of a thin superconducting wire (nanowire) is reduced, its critical temperature diminishes and a transition to an insulating regime is observed. Such transition appears to be a quantum superconductor-insulator transition (SIT) [1]. The SIT in nanowires shows...

The Kondo exciton: a quantum quench towards strong spin-reservoir correlations

Tuesday 11th may 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Hakan Tureci (ETH Zurich, Switzerland) When a quantum system is subjected to a quantum quench, i.e. a sudden change of some parameters of the Hamiltonian, its subsequent dynamics is governed by energy scales that become ever lower with increasing time: whereas the transient behavior right after the quench depends on...

Population switching and charge sensing in quantum dots: A case for quantum phase transitions

Tuesday 5th may 2010 at 4pm CNRS Bât K, on 1st floor - Room to be confirmed Moshe Goldstein (Department of Physics, Bar-Ilan University, Israel) “Population switching'' is a phenomenon involving a steep filling of a narrow level in a quantum dot at the expense of a wide one as a common gate voltage is varied. This effect has been discussed in several...

Superconducting triplet spin valve

Tuesday 20th April 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Yakov FOMINOV (Institut Landau, Moscou) We study the critical temperature T c of SFF trilayers (S is a singlet superconductor, F is a ferromagnetic metal), where the long-range triplet superconducting component is generated at noncollinear magnetizations of the F layers. We demonstrate that T c...

Luttinger liquid in presence of a bath

Tuesday 13th April 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Thierry GIAMARCHI (University of Genève) In one dimension interactions lead to a physics dominated by interactions. One of the cornerstones to describe such physcis is provided by the Luttinger liquid theory, equivalent in one dimension of the Fermi liquid for the higher dimensional systems. A very interesting...

Recent Experimental Developments In Nanomagnetic Logic

Tuesday 6th April 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Alexei ORLOV (University of Notre-Dame, Indiana, USA) We present recent developments in the field of nano-magnetic logic (NML, formerly a.k.a. M-QCA) where planar, magnetically-coupled, nanometer-scale magnets are assembled into networks that perform binary computation driven by global ("clocking ") fields and local...

Resistance of pn- junctions in strongly correlated armchair nanotubes

Tuesday 23rd March 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Anton ANDREEV (University of Washington, Seattle) I will discuss low temperature magnetoresistance of a pn-junction in an armchair carbon nanotube. Strong Luttinger correlations of electron liquid in armchair tubes have a dramatic influence on the temperature dependence of the...

Fully Overheated Single-Electron Transistor

Tuesday 16 March 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Yuli V. Nazarov (Kavli Institute of Nanoscience, Delft - The Netherlands) We consider the fully overheated single-electron transistor, where the heat balance is determined entirely by electron transfers. We find three distinct transport regimes corresponding to cotunneling, single-electron tunneling, and a competition between the two. We find an anomalous...

Landau-Zener-Stuckelberg interferometry in superconducting qubits

Tuesday 9 March 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Sergio O. Valenzuela (Institut Català de Nanotecnologia - Bellaterra, Espagne) Superconducting persistent-current qubits are quantum-coherent artificial atoms with multiple energy levels. In the presence of large-amplitude harmonic excitation, the qubit state can be driven through one or more of the...

Dimensional Crossover of the Dephasing Time in Disordered Mesoscopic Rings

Tuesday 2nd march 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Oleg Yevtushenko (University of Munich, Germany) We study dephasing by electron interactions in a small disordered quasi-one dimensional ring weakly coupled to leads. We use an influence functional for quantum Nyquist noise to describe the crossover for the dephasing time from diffusive or ergodic 1D to 0D behavior as temperature drops below the...

Probing a single dopant in ultra-scaled CMOS transistors

Tuesday 26 January 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Xavier Jehl (INAC, SPSMS, CEA Grenoble) We use the microelectronics technology to fabricate silicon transistors channels with a very small volume, i.e. short, narrow and thin (10x50x20 nm). Low temperature spectroscopy of such devices reveals the characteristics of single dopants which have...

Phase-charge duality in Josephson junction circuits: Role of inertia and effect of microwave irradiation

Tuesday 19 january 2009 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Frank Hekking (LPMMC, CNRS et UJF) We investigate the physics of coherent quantum phase slips in two distinct circuits containing small Josephson junctions: a single junction embedded in an inductive environment and a long chain of junctions. Starting from the standard Josephson Hamiltonian, the single junction circuit can be analyzed...

Anatomy of the fractional quantum Hall states

Tuesday 12 January 2010 at 4pm CNRS Bât E, conference room "Louis Weil" on 3rd floor Nicolas Regnault (Laboratoire Pierre Aigrain, Ecole Normale Supérieure, Paris) Understanding of numerous phenomena in physics or chemistry are based on the underlying fermionic or bosonic statistics. While statistics beyond these two have been predicted or more than twenty years, the experimental evidences of fractional or non-abelian...