Thomas Liennard - Academia.edu (original) (raw)
Address: Paris, Île-de-France, France
less
Uploads
Papers by Thomas Liennard
Physical Review A, Jan 31, 2012
We describe an experiment to produce 87 Rb Bose-Einstein condensates in an optically plugged magn... more We describe an experiment to produce 87 Rb Bose-Einstein condensates in an optically plugged magnetic quadrupole trap, using a blue-detuned laser. Due to the large detuning of the plug laser with respect to the atomic transition, the evaporation has to be carefully optimized in order to efficiently overcome the Majorana losses. We provide a complete theoretical and experimental study of the trapping potential at low temperatures and show that this simple model describes well our data. In particular we demonstrate methods to reliably measure the trap oscillation frequencies and the bottom frequency, based on periodic excitation of the trapping potential and on radio-frequency spectroscopy, respectively. We show that this hybrid trap can be operated in a well controlled regime that allows a reliable production of degenerate gases.
Physical Review A, 2012
We analyze the excitation spectrum of a superfluid Bose-Einstein condensate rotating in a ring tr... more We analyze the excitation spectrum of a superfluid Bose-Einstein condensate rotating in a ring trap. We identify two important branches of the spectrum related to outer and inner edge surface modes that lead to the instability of the superfluid. Depending on the initial circulation of the annular condensate, either the outer or the inner modes become first unstable. This instability is crucially related to the superfluid nature of the rotating gas. In particular we point out the existence of a maximal circulation above which the superflow decays spontaneously, which cannot be explained by invoking the average speed of sound.
![Research paper thumbnail of Erratum: Rubidium-87 Bose-Einstein condensate in an optically plugged quadrupole trap [Phys. Rev. A <span xmlns:xlink="http://www.w3.org/1999/xlink" style="font-weight: bold;">85</span>, 013643 (2012)]](https://attachments.academia-assets.com/94880376/thumbnails/1.jpg)
](
Http Www Theses Fr, Dec 9, 2011
etétude théorique d'un superfluide en rotation dans un anneau Soutenue le 9 décembre 2011 devant ... more etétude théorique d'un superfluide en rotation dans un anneau Soutenue le 9 décembre 2011 devant le jury composé par :
2019 IEEE Sensors Applications Symposium (SAS)
Lane information is essential for safe autonomous driving. In this article, we present a multisen... more Lane information is essential for safe autonomous driving. In this article, we present a multisensor fusion framework for ego and adjacent lanes with a novel fusion quality measure and dynamic lane mode strategies for erroneous management. The framework fuses road marking lines based on Dempster-Shafer theory and tracks lanes with a particle filter. Then, a quality measure for each line is computed, integrating sensor coherence, availability as well as temporal continuity. This quality is essential to deploy different lane management strategies in order to avoid integrating erroneous data. The proposed framework was evaluated in a lateral control architecture with autonomous driving on open roads and proved its robustness and availability.
CATS is a collaborative European project promoting driverless vehicles that ended in December 201... more CATS is a collaborative European project promoting driverless vehicles that ended in December 2014. This contribution explains how the project evolved, including the handling of unexpected events and concentrating on lessons learned. The constructor and vehicle had to be changed for economic reasons in the middle of the project timeline. A second constructor went bankrupt, although access to his vehicles could be secured. For security and legal reasons, part of the final demonstration was relocated at short notice to the EPFL campus in Lausanne, Switzerland, where around 1600 people were transported during 16 days of vehicle operation. Reactions to the driverless vehicle concept were overwhelmingly positive. Implications for the acceptability of driverless vehicles in Europe and elsewhere are discussed.
Physical Review A, Jan 31, 2012
We describe an experiment to produce 87 Rb Bose-Einstein condensates in an optically plugged magn... more We describe an experiment to produce 87 Rb Bose-Einstein condensates in an optically plugged magnetic quadrupole trap, using a blue-detuned laser. Due to the large detuning of the plug laser with respect to the atomic transition, the evaporation has to be carefully optimized in order to efficiently overcome the Majorana losses. We provide a complete theoretical and experimental study of the trapping potential at low temperatures and show that this simple model describes well our data. In particular we demonstrate methods to reliably measure the trap oscillation frequencies and the bottom frequency, based on periodic excitation of the trapping potential and on radio-frequency spectroscopy, respectively. We show that this hybrid trap can be operated in a well controlled regime that allows a reliable production of degenerate gases.
Physical Review A, 2012
We analyze the excitation spectrum of a superfluid Bose-Einstein condensate rotating in a ring tr... more We analyze the excitation spectrum of a superfluid Bose-Einstein condensate rotating in a ring trap. We identify two important branches of the spectrum related to outer and inner edge surface modes that lead to the instability of the superfluid. Depending on the initial circulation of the annular condensate, either the outer or the inner modes become first unstable. This instability is crucially related to the superfluid nature of the rotating gas. In particular we point out the existence of a maximal circulation above which the superflow decays spontaneously, which cannot be explained by invoking the average speed of sound.
Http Www Theses Fr, Dec 9, 2011
etétude théorique d'un superfluide en rotation dans un anneau Soutenue le 9 décembre 2011 devant ... more etétude théorique d'un superfluide en rotation dans un anneau Soutenue le 9 décembre 2011 devant le jury composé par :
2019 IEEE Sensors Applications Symposium (SAS)
Lane information is essential for safe autonomous driving. In this article, we present a multisen... more Lane information is essential for safe autonomous driving. In this article, we present a multisensor fusion framework for ego and adjacent lanes with a novel fusion quality measure and dynamic lane mode strategies for erroneous management. The framework fuses road marking lines based on Dempster-Shafer theory and tracks lanes with a particle filter. Then, a quality measure for each line is computed, integrating sensor coherence, availability as well as temporal continuity. This quality is essential to deploy different lane management strategies in order to avoid integrating erroneous data. The proposed framework was evaluated in a lateral control architecture with autonomous driving on open roads and proved its robustness and availability.
CATS is a collaborative European project promoting driverless vehicles that ended in December 201... more CATS is a collaborative European project promoting driverless vehicles that ended in December 2014. This contribution explains how the project evolved, including the handling of unexpected events and concentrating on lessons learned. The constructor and vehicle had to be changed for economic reasons in the middle of the project timeline. A second constructor went bankrupt, although access to his vehicles could be secured. For security and legal reasons, part of the final demonstration was relocated at short notice to the EPFL campus in Lausanne, Switzerland, where around 1600 people were transported during 16 days of vehicle operation. Reactions to the driverless vehicle concept were overwhelmingly positive. Implications for the acceptability of driverless vehicles in Europe and elsewhere are discussed.