I’am a CNRS senior researcher (DR1) and I work within the Theoretical Physics team of the Physics Laboratory at the Ecole Normale Supérieure of Lyon.
My present research aims at developing a theoretical framework for electron quantum optics, an emerging field that aims at the manipulation of the quantum state of single to few electrons in a conductor. Supervisors: PhD advisor: B. Julia (defended in 1992)
ABSTRACT Coulomb interactions play a major role in one dimensional electronic transport. They mod... more ABSTRACT Coulomb interactions play a major role in one dimensional electronic transport. They modify the nature of the elementary excitations from Landau quasiparticles in higher dimensions to collective excitations in 1D. We report here on the direct observation of the collective neutral and charge modes of the two chiral co-propagating edge channels of opposite spins of the quantum Hall effect at filling factor ν=2. Generating a charge density wave at frequency f in the outer channel, we measure the current induced by inter-channel Coulomb interaction in the inner channel after a 3 microns propagation length. Varying the driving frequency from 0.7 to 11 GHz, we observe damped oscillations in the induced current that results from the phase shift between the fast charge and slow neutral eigenmodes. Measuring the dispersion relation and dissipation of the neutral mode from provides quantitative information on the scattering of quantum edge magnetoplasmons. We will then comment on the consequences of these results on quasi-particle relaxation and decoherence in the ν=2 quantum Hall edge channel system.
Coulomb interactions have a major role in one-dimensional electronic transport. They modify the n... more Coulomb interactions have a major role in one-dimensional electronic transport. They modify the nature of the elementary excitations from Landau quasiparticles in higher dimensions to collective excitations in one dimension. Here we report the direct observation of the collective neutral and charge modes of the two chiral co-propagating edge channels of opposite spins of the quantum Hall effect at filling factor 2. Generating a charge density wave at frequency f in the outer channel, we measure the current induced by inter-channel Coulomb interaction in the inner channel after a 3-μm propagation length. Varying the driving frequency from 0.7 to 11 GHz, we observe damped oscillations in the induced current that result from the phase shift between the fast charge and slow neutral eigenmodes. We measure the dispersion relation and dissipation of the neutral mode from which we deduce quantitative information on the interaction range and parameters.
ABSTRACT The ballistic propagation of electronic waves in the quantum Hall edge channels of a 2DE... more ABSTRACT The ballistic propagation of electronic waves in the quantum Hall edge channels of a 2DEG bears strong analogies with photon optics which inspired a whole set of experiments, including the realization of electronic Mach-Zehnder [1] and Hanbury-Brown and Twiss [2] interferometers. So far, these experiments have been performed with continuous sources, but the recent realization of on-demand single electron emitters [3] has risen the hope to reach, in these experiments, the single charge control. We report here on the first realization of a Hanbury-Brown and Twiss experiment on a single electron beam generated by the single electron emitter recently developed by our group [3]. Using the chiral edge channels of the quantum Hall effect, single electron emitted by the source are directed towards an electronic beam-splitter. From the low frequency current correlations at the output of the beam splitter, we are able to count and characterize the elementary excitations produced by the source. By analyzing their antibunching with thermal excitations, we show that we are able to shape single particle states in a tuneable way. [1] Ji et al., Nature 422, 415 (2003) [2] Henny et al., Science 284 296 (1999) [3] Fève et al., Science 316, 1169 (2007)
ABSTRACT We present an experimental study of the low frequency admittance of quantum Hall conduct... more ABSTRACT We present an experimental study of the low frequency admittance of quantum Hall conductors in the [100 Hz, 1 MHz] frequency range. We show that the frequency dependence of the admittance of the sample strongly depends on the topology of the contacts connections. Our experimental results are well explained within the Christen and Büttiker approach for finite frequency transport in quantum Hall edge channels taking into account the influence of the coaxial cables capacitance. In the Hall bar geometry, we demonstrate that there exists a configuration in which the cable capacitance does not influence the admittance measurement of the sample. In this case, we measure the electrochemical capacitance of the sample and observe its dependence on the filling factor.
Motivated by recent experiments with Josephson qubits we propose a new phenomenological model for... more Motivated by recent experiments with Josephson qubits we propose a new phenomenological model for /f noise due to collective excitations of interacting defects in the qubit's environment. At very low temperatures the effective dynamics of these collective modes are very slow leading to pronounced non-Gaussian features and nonstationarity of the noise. We analyze the influence of this noise on the dynamics of a qubit in various regimes and at different operation points. Remarkable predictions are absolute time dependences of a critical coupling and of dephasing in the strong coupling regime.
ABSTRACT Coulomb interactions play a major role in one dimensional electronic transport. They mod... more ABSTRACT Coulomb interactions play a major role in one dimensional electronic transport. They modify the nature of the elementary excitations from Landau quasiparticles in higher dimensions to collective excitations in 1D. We report here on the direct observation of the collective neutral and charge modes of the two chiral co-propagating edge channels of opposite spins of the quantum Hall effect at filling factor ν=2. Generating a charge density wave at frequency f in the outer channel, we measure the current induced by inter-channel Coulomb interaction in the inner channel after a 3 microns propagation length. Varying the driving frequency from 0.7 to 11 GHz, we observe damped oscillations in the induced current that results from the phase shift between the fast charge and slow neutral eigenmodes. Measuring the dispersion relation and dissipation of the neutral mode from provides quantitative information on the scattering of quantum edge magnetoplasmons. We will then comment on the consequences of these results on quasi-particle relaxation and decoherence in the ν=2 quantum Hall edge channel system.
Coulomb interactions have a major role in one-dimensional electronic transport. They modify the n... more Coulomb interactions have a major role in one-dimensional electronic transport. They modify the nature of the elementary excitations from Landau quasiparticles in higher dimensions to collective excitations in one dimension. Here we report the direct observation of the collective neutral and charge modes of the two chiral co-propagating edge channels of opposite spins of the quantum Hall effect at filling factor 2. Generating a charge density wave at frequency f in the outer channel, we measure the current induced by inter-channel Coulomb interaction in the inner channel after a 3-μm propagation length. Varying the driving frequency from 0.7 to 11 GHz, we observe damped oscillations in the induced current that result from the phase shift between the fast charge and slow neutral eigenmodes. We measure the dispersion relation and dissipation of the neutral mode from which we deduce quantitative information on the interaction range and parameters.
ABSTRACT The ballistic propagation of electronic waves in the quantum Hall edge channels of a 2DE... more ABSTRACT The ballistic propagation of electronic waves in the quantum Hall edge channels of a 2DEG bears strong analogies with photon optics which inspired a whole set of experiments, including the realization of electronic Mach-Zehnder [1] and Hanbury-Brown and Twiss [2] interferometers. So far, these experiments have been performed with continuous sources, but the recent realization of on-demand single electron emitters [3] has risen the hope to reach, in these experiments, the single charge control. We report here on the first realization of a Hanbury-Brown and Twiss experiment on a single electron beam generated by the single electron emitter recently developed by our group [3]. Using the chiral edge channels of the quantum Hall effect, single electron emitted by the source are directed towards an electronic beam-splitter. From the low frequency current correlations at the output of the beam splitter, we are able to count and characterize the elementary excitations produced by the source. By analyzing their antibunching with thermal excitations, we show that we are able to shape single particle states in a tuneable way. [1] Ji et al., Nature 422, 415 (2003) [2] Henny et al., Science 284 296 (1999) [3] Fève et al., Science 316, 1169 (2007)
ABSTRACT We present an experimental study of the low frequency admittance of quantum Hall conduct... more ABSTRACT We present an experimental study of the low frequency admittance of quantum Hall conductors in the [100 Hz, 1 MHz] frequency range. We show that the frequency dependence of the admittance of the sample strongly depends on the topology of the contacts connections. Our experimental results are well explained within the Christen and Büttiker approach for finite frequency transport in quantum Hall edge channels taking into account the influence of the coaxial cables capacitance. In the Hall bar geometry, we demonstrate that there exists a configuration in which the cable capacitance does not influence the admittance measurement of the sample. In this case, we measure the electrochemical capacitance of the sample and observe its dependence on the filling factor.
Motivated by recent experiments with Josephson qubits we propose a new phenomenological model for... more Motivated by recent experiments with Josephson qubits we propose a new phenomenological model for /f noise due to collective excitations of interacting defects in the qubit's environment. At very low temperatures the effective dynamics of these collective modes are very slow leading to pronounced non-Gaussian features and nonstationarity of the noise. We analyze the influence of this noise on the dynamics of a qubit in various regimes and at different operation points. Remarkable predictions are absolute time dependences of a critical coupling and of dephasing in the strong coupling regime.
We compute the modular properties of the possible genus-one characters of some Rational Conformal... more We compute the modular properties of the possible genus-one characters of some Rational Conformal Field Theories starting from their fusion rules. We show that the possible choices of S matrices are indexed by some automorphisms of the fusion algebra. We also classify the modular invariant partition functions of these theories. This gives the complete list of modular invariant partition functions of Rational Conformal Field Theories with respect to the Aff level one algebra.
clicking here. colleagues, clients, or customers by , you can order high-quality copies for your ... more clicking here. colleagues, clients, or customers by , you can order high-quality copies for your If you wish to distribute this article to others here. following the guidelines can be obtained by Permission to republish or repurpose articles or portions of articles ): February 28, 2013 www.sciencemag.org (this information is current as of The following resources related to this article are available online at http://www.sciencemag.org/content/339/6123/1054.full.html version of this article at: including high-resolution figures, can be found in the online Updated information and services, http://www.sciencemag.org/content/339/6123/1054.full.html#related found at: can be related to this article A list of selected additional articles on the Science Web sites http://www.sciencemag.org/content/339/6123/1054.full.html#ref-list-1 , 3 of which can be accessed free: cites 27 articles This article http://www.sciencemag.org/cgi/collection/physics Physics subject collections: This article appea...
We derive non equilibrium statistical ensembles for a ballistic Aharonov-Bohm loop connected to s... more We derive non equilibrium statistical ensembles for a ballistic Aharonov-Bohm loop connected to several electrodes connected to reservoirs with different chemical potentials. A striking consequence of these non trivial ensembles is the emergence of quantum zero point fluctuations of the persistent current around the loop. Detailed predictions for the low frequency noise power are given.
Although interesting per se, decoherence and relaxation of single-electron excitations induced by... more Although interesting per se, decoherence and relaxation of single-electron excitations induced by strong effective screened Coulomb interactions in Quantum Hall edge channels are an important challenge for the applications of electron quantum optics in quantum information and quantum sensing. In this paper, we study intrinsic single-electron decoherence within an ideal single-electron channel with long-range effective Coulomb interactions to determine the influence of the material and sample properties. We find that weak-coupling materials characterized by a high velocity of hot-electron excitations may offer interesting perspectives for limiting intrinsic decoherence due to electron/electron interactions. We discuss quantitively how extrinsic decoherence due to the coupling with the channel’s electromagnetic environment can be efficiently inhibited in specially designed samples at ν = 2 with one closed edge channel and we propose a realistic geometry for testing decoherence control...
Depuis la fin du xxe siècle, la théorie quantique connaît un renouveau qui se traduit par l’émerg... more Depuis la fin du xxe siècle, la théorie quantique connaît un renouveau qui se traduit par l’émergence de technologies utilisant toute la puissance des interférences quantiques pour mesurer, simuler, communiquer et calculer.
Parallèlement, cette « seconde révolution quantique » remet en question notre compréhension de la théorie quantique et nous pousse à dépasser la vision purement utilitariste de l’interprétation de Copenhague. part, il vise à utiliser cette exploration pour éclairer le sens de la théorie quantique en insistant sur l’absence d’état objectif défini sans référence à un observateur. Il s’agit du premier (et seul) ouvrage qui présente une synthèse de l’ensemble de ces sujets.
Cet ouvrage a donc un double objectif : d’une part il donne une introduction globale au domaine des technologies quantiques en présentant les relations entre théorie quantique, théorie de l’information et informatique ; d’autre part, il vise à éclairer le sens de la théorie quantique en se focalisant sur la notion d’état quantique. L’ensemble de ces sujets est présenté en une synthèse originale.
Ce premier volume offre au lecteur, qu’il soit physicien, ingénieur, mathématicien ou informaticien, de se fami- liariser avec les technologies quantiques. Une discussion des systèmes d’électrodynamique en cavité : atomes en cavité et aussi circuits supraconducteurs, illustre concrètement nombre d’idées et méthodes.
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Parallèlement, cette « seconde révolution quantique » remet en question notre compréhension de la théorie quantique et nous pousse à dépasser la vision purement utilitariste de l’interprétation de Copenhague.
part, il vise à utiliser cette exploration pour éclairer le sens de la théorie quantique en insistant sur l’absence d’état objectif défini sans référence à un observateur. Il s’agit du premier (et seul) ouvrage qui présente une synthèse de l’ensemble de ces sujets.
Cet ouvrage a donc un double objectif : d’une part il donne une introduction globale au domaine des technologies quantiques en présentant les relations entre théorie quantique, théorie de l’information et informatique ; d’autre part, il vise à éclairer le sens de la théorie quantique en se focalisant sur la notion d’état quantique. L’ensemble de ces sujets est présenté en une synthèse originale.
Ce premier volume offre au lecteur, qu’il soit physicien, ingénieur, mathématicien ou informaticien, de se fami- liariser avec les technologies quantiques. Une discussion des systèmes d’électrodynamique en cavité : atomes en cavité et aussi circuits supraconducteurs, illustre concrètement nombre d’idées et méthodes.