Concept

Electronic countermeasure

Publications associées (86)

Anti-spoofing in action: joint operation with a verification system

Sébastien Marcel, André Anjos, Ivana Chingovska

Besides the recognition task, today's biometric systems need to cope with additional problem: spoofing attacks. Up to date, academic research considers spoofing as a binary classification problem: systems are trained to discriminate between real accesses a ...

2013

Direct observation of non-fully-symmetric coherent optical phonons by femtosecond x-ray diffraction

Paul Beaud

We directly measure by femtosecond time-resolved x-ray diffraction the E-g symmetry coherent phonon excited in bismuth by a strong optical pulse. The magnitude of the E-g mode observed is 0.2 pm peak-to-peak, compared against the 2.7-pm initial displacemen ...

American Physical Society2013

Excitation of Coherent Phonons in the One-Dimensional Bi(114) Surface

Jan Hugo Dil

We present time-resolved photoemission experiments from a peculiar bismuth surface, Bi(114). The strong one-dimensional character of this surface is reflected in the Fermi surface, which consists of spin-polarized straight lines. Our results show that the ...

2013

Hartree simulations of coupled quantum Hall edge states in corner-overgrown heterostructures

The electronic states in a corner-overgrown bent GaAs/AlGaAs quantum well heterostructure are studied with numerical Hartree simulations. Transmission electron microscope pictures of the junction sharpness are shown to justify the sharp-corner potential as ...

American Physical Society2013

Electronic and magnetic properties of bulk Cr tips for scanning tunneling spectroscopy

Fabio Donati

The electronic and magnetic properties of bulk Cr tips for scanning tunneling microscopy have been investigated by means of density functional theory (DFT) calculations and scanning tunneling spectroscopy (STS) measurements. Spin-resolved densities of stat ...

American Physical Society2013

Adsorbate-Induced Modification of Surface Electronic Structure: Pyrocatechol Adsorption on the Anatase TiO2 (101) and Rutile TiO2 (110) Surfaces

Michael Graetzel

Photoemission and near-edge X-ray absorption fine structure (NEXAFS) techniques have been used to study the adsorption of pyrocatechol on anatase TiO2 (101) and rutile TiO2 (110) single crystals. Photoemission results suggest the pyrocatechol molecule adso ...

American Chemical Society2012

Electronic, vibrational, and transport properties of pnictogen-substituted ternary skutterudites

Nicola Marzari, Boris Kozinsky

First principles calculations are used to investigate electronic band structure and vibrational spectra of pnictogen-substituted ternary skutterudites. We compare the results with the prototypical binary composition CoSb3 to identify the effects of substit ...

2012

Evaluation of the importance of spin-orbit couplings in the nonadiabatic quantum dynamics with quantum fidelity and with its efficient “on-the-fly” ab initio semiclassical approximation

Jiri Vanicek, Tomas Zimmermann

We propose to measure the importance of spin-orbit couplings (SOCs) in the nonadiabatic molecular quantum dynamics rigorously with quantum ﬁdelity. To make the criterion practical, quantum ﬁdelity is estimated efﬁciently with the multiple-surface dephasing ...

American Institute of Physics2012

Investigation of coherent acoustic phonons in terahertz quantum cascade laser structures using femtosecond pump-probe spectroscopy

Elyahou Kapon, Alok Rudra, Pascal Gallo, Jérôme Faist

The dynamics of acoustic vibrations in terahertz quantum cascade laser structures (THz-QCLs) is studied by means of femtosecond pump-probe spectroscopy. The phonon modes are characterized by the folding of the acoustic dispersion into an effective reduced ...

Amer Inst Physics2012

Defects and localization in chemically-derived graphene

László Forró, Arnaud Magrez, Andrzej Sienkiewicz, Richard Gaal, Luka Ciric, Jacim Jacimovic, George Cristian Vaju

We have performed electron spin resonance (ESR) measurements on a large assembly of graphene oxide (GO) and reduced graphene oxide (RGO) flakes. In GO samples the Curie tail is coming from 1.4 x 10(18) cm(-3) of localized spins. Although reduction of GO wa ...

Amer Physical Soc2012

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