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Sterdyniak A.,University of Innsbruck | Bernevig B.A.,Princeton University | Cooper N.R.,Tcm Group | Regnault N.,Princeton University | Regnault N.,CNRS Pierre Aigrain Laboratory
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

An interesting route to the realization of topological Chern bands in ultracold atomic gases is through the use of optical flux lattices. These models differ from the tight-binding real-space lattice models of Chern insulators that are conventionally studied in solid-state contexts. Instead, they involve the coherent coupling of internal atomic (spin) states, and can be viewed as tight-binding models in reciprocal space. By changing the form of the coupling and the number N of internal spin states, they give rise to Chern bands with controllable Chern number and with nearly flat energy dispersion. We investigate in detail how interactions between bosons occupying these bands can lead to the emergence of fractional quantum Hall states, such as the Laughlin and Moore-Read states. In order to test the experimental realization of these phases, we study their stability with respect to band dispersion and band mixing. We also probe interesting topological phases that emerge in these systems when the Chern number is greater than 1. © 2015 American Physical Society.

Pillet J.-D.,CEA Saclay Nuclear Research Center | Quay C.H.L.,CEA Saclay Nuclear Research Center | Quay C.H.L.,University Paris - Sud | Morfin P.,CNRS Pierre Aigrain Laboratory | And 4 more authors.
Nature Physics | Year: 2010

Carbon nanotubes (CNTs) are not intrinsically superconducting but they can carry a supercurrent when connected to superconducting electrodes1-4. This supercurrent is mainly transmitted by discrete entangled electron-hole states confined to the nanotube, called Andreev bound states (ABS). These states are a key concept in mesoscopic superconductivity as they provide a universal description of Josephson-like effects in quantum-coherent nanostructures (for example molecules, nanowires, magnetic or normal metallic layers) connected to superconducting leads5. We report here the first tunnelling spectroscopy of individually resolved ABS, in a nanotube-superconductor device. Analysing the evolution of the ABS spectrum with a gate voltage, we show that the ABS arise from the discrete electronic levels of the molecule and that they reveal detailed information about the energies of these levels, their relative spin orientation and the coupling to the leads. Such measurements hence constitute a powerful new spectroscopic technique capable of elucidating the electronic structure of CNT-based devices, including those with well-coupled leads. This is relevant for conventional applications (for example, superconducting or normal transistors, superconducting quantum interference devices3 (SQUIDs)) and quantum information processing (for example, entangled electron pair generation6,7, ABS-based qubits8). Finally, our device is a new type of d.c.-measurable SQUID. © 2010 Macmillan Publishers Limited. All rights reserved.

Herrmann L.G.,Ecole Normale Superieure de Paris | Herrmann L.G.,CNRS Pierre Aigrain Laboratory | Herrmann L.G.,University of Regensburg | Portier F.,CEA Saclay Nuclear Research Center | And 5 more authors.
Physical Review Letters | Year: 2010

We report on conductance measurements in carbon nanotube based double quantum dots connected to two normal electrodes and a central superconducting finger. By operating our devices as beam splitters, we provide evidence for crossed Andreev reflections tunable in situ. This opens an avenue to more sophisticated quantum opticslike experiments with spin entangled electrons. © 2010 The American Physical Society.

Roch N.,CNRS Pierre Aigrain Laboratory | Flurin E.,CNRS Pierre Aigrain Laboratory | Nguyen F.,CNRS Pierre Aigrain Laboratory | Nguyen F.,U.S. National Institute of Standards and Technology | And 6 more authors.
Physical Review Letters | Year: 2012

We present the first experimental realization of a widely frequency tunable, nondegenerate three-wave mixing device for quantum signals at gigahertz frequency. It is based on a new superconducting building block consisting of a ring of four Josephson junctions shunted by a cross of four linear inductances. The phase configuration of the ring remains unique over a wide range of magnetic fluxes threading the loop. It is thus possible to vary the inductance of the ring with flux while retaining a strong, dissipation-free, and noiseless nonlinearity. The device has been operated in amplifier mode, and its noise performance has been evaluated by using the noise spectrum emitted by a voltage-biased tunnel junction at finite frequency as a test signal. The unprecedented accuracy with which the crossover between zero-point fluctuations and shot noise has been measured provides an upper bound for the noise and dissipation intrinsic to the device. © 2012 American Physical Society.

Betz A.C.,CNRS Pierre Aigrain Laboratory | Jhang S.H.,CNRS Pierre Aigrain Laboratory | Pallecchi E.,CNRS Pierre Aigrain Laboratory | Pallecchi E.,CNRS Optic of Semiconductor nanoStructures Group | And 4 more authors.
Nature Physics | Year: 2013

Carrier mobility in solids is generally limited by electron-impurity or electron-phonon scattering, depending on the most frequently occurring event. Three-body collisions between carriers and both phonons and impurities are rare; they are denoted supercollisions. Elusive in electronic transport they should emerge in relaxation processes as they allow for larger energy transfers. This is the case in undoped graphene, where the small Fermi surface drastically restricts the allowed phonon energy in ordinary collisions. Using electrical heating and sensitive noise thermometry we report on supercollision cooling in diffusive monolayer graphene. At low carrier density and high phonon temperature the Joule power P obeys a PT e 3 law as a function of electronic temperature T e. It overrules the linear law expected for ordinary collisions which has recently been observed in resistivity measurements. The cubic law is characteristic of supercollisions and departs from the T e 4 dependence recently reported for doped graphene below the Bloch-Grüneisen temperature. These supercollisions are important for applications of graphene in bolometry and photo-detection. © 2013 Macmillan Publishers Limited. All rights reserved.

Wu Y.-L.,Princeton University | Estienne B.,Paris-Sorbonne University | Estienne B.,CNRS Theoretical and High Energy Physics | Regnault N.,Princeton University | And 2 more authors.
Physical Review Letters | Year: 2014

Quasiholes in certain fractional quantum Hall states are promising candidates for the experimental realization of non-Abelian anyons. They are assumed to be localized excitations, and to display non-Abelian statistics when sufficiently separated, but these properties have not been explicitly demonstrated except for the Moore-Read state. In this work, we apply the newly developed matrix product state technique to examine these exotic excitations. For the Moore-Read and the Z3 Read-Rezayi states, we estimate the quasihole radii, and determine the correlation lengths associated with the exponential convergence of the braiding statistics. We provide the first microscopic verification for the Fibonacci nature of the Z3 Read-Rezayi quasiholes. We also present evidence for the failure of plasma screening in the nonunitary Gaffnian wave function. © 2014 American Physical Society.

Filippone M.,CNRS Pierre Aigrain Laboratory | Dusuel S.,Lycee Saint Louis | Vidal J.,University Pierre and Marie Curie
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We consider a set of fully connected spin models that display first- or second-order transitions and for which we compute the ground-state entanglement in the thermodynamical limit. We analyze several entanglement measures (concurrence, Rényi entropy, and negativity) and show that, in general, discontinuous transitions lead to a jump of these quantities at the transition point. Interestingly, we also find examples where this is not the case. © 2011 American Physical Society.

Cottet A.,CNRS Pierre Aigrain Laboratory | Mora C.,CNRS Pierre Aigrain Laboratory | Kontos T.,CNRS Pierre Aigrain Laboratory
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We calculate the mesoscopic admittance G(ω) of a double quantum dot (DQD), which can be measured directly using microwave techniques. This quantity reveals spectroscopic information on the DQD and is also directly sensitive to a Pauli spin blockade effect. We then discuss the problem of a DQD coupled to a high quality photonic resonator. When the photon correlation functions can be developed along a random-phase-approximation-like scheme, the response of the resonator gives an access to G(ω). © 2011 American Physical Society.

Delbecq M.R.,CNRS Pierre Aigrain Laboratory | Bruhat L.E.,CNRS Pierre Aigrain Laboratory | Viennot J.J.,CNRS Pierre Aigrain Laboratory | Datta S.,CNRS Pierre Aigrain Laboratory | And 2 more authors.
Nature Communications | Year: 2013

Engineering the interaction between light and matter is an important goal in the emerging field of quantum opto-electronics. Thanks to the use of cavity quantum electrodynamics architectures, one can envision a fully hybrid multiplexing of quantum conductors. Here we use such an architecture to couple two quantum dot circuits. Our quantum dots are separated by 200 times their own size, with no direct tunnel and electrostatic couplings between them. We demonstrate their interaction, mediated by the cavity photons. This could be used to scale up quantum bit architectures based on quantum dot circuits or simulate on-chip phonon-mediated interactions between strongly correlated electrons. © 2013 Macmillan Publishers Limited. All rights reserved.

Hale P.J.,Okinawa Institute of Science and Technology | Madeo J.,Okinawa Institute of Science and Technology | Chin C.,Okinawa Institute of Science and Technology | Dhillon S.S.,CNRS Pierre Aigrain Laboratory | And 3 more authors.
Optics Express | Year: 2014

We demonstrate broadband (20 THz), high electric field, terahertz generation using large area interdigitated antennas fabricated on semi-insulating GaAs. The bandwidth is characterized as a function of incident pulse duration (15-35 fs) and pump energy (2-30 nJ). Broadband spectroscopy of PTFE is shown. Numerical Drude-Lorentz simulations of the generated THz pulses are performed as a function of the excitation pulse duration, showing good agreement with the experimental data. © 2014 Optical Society of America.

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