Xavier LEYRONAS

Maître de Conférences (Assistant Professor)
Université Pierre et Marie Curie (Paris 6)

Address:
Laboratoire de Physique Statistique
Ecole Normale Supérieure
24 rue Lhomond
75231 Paris Cedex 05

Office: L286
Phone number: +33 1 44 32 34 76
Fax number: +33 1 44 32 34 33

E-mail : leyronas@lps.ens.fr

Research interests

Ultracold Fermi gases
Hydrodynamic modes
Collapse instability
BEC-BCS crossover
3 and 4 body problem (using Feynman diagrams)
Virial expansion

High-Tc superconductors
Strong coupling electron-phonon theory (Eliashberg theory)
Cu-O plane-chain model

Mesoscopic physics
Anderson localization in Fock space
Excitons
Electronic transport through a Kondo impurity

Publications

Full list (updated november 2016)

BEC-BCS crossover
P. P. Crépin, X. Leyronas, and F. Chevy Hydrodynamic spectrum of a superfluid in an elongated trap, Euro. Phys. Lett., 114 (2016) 60005 pdf
T. Kristensen, X. Leyronas, and L. Pricoupenko Second-order virial expansion for an atomic gas in a harmonic waveguide, Phys. Rev. A 93, 063636 (2016) pdf
M. Sun and X. Leyronas High temperature expansion of interacting fermions, Phys. Rev. A 92, 053611 (2015) pdf
S. Laurent, X. Leyronas and F. Chevy Momentum distribution of a dilute unitary Bose gas with three-body losses, Phys. Rev. Lett. 113, 220601 (2014) pdf
N. Navon, S. Nascimbene, X. Leyronas, F. Chevy and C. Salomon Condensation energy of a spin-1/2 strongly interacting Fermi gas, Phys. Rev. A 88, 063614, (2013) pdf
X. Leyronas, Virial expansion with Feynman diagrams, Phys. Rev. A 84, 053633 (2011) pdf
F. Alzetto and X. Leyronas, Equation of state of a polarized Fermi gas in the Bose-Einstein Condensate limit, Phys. Rev. A. 81, 043604 (2010) pdf
R. Combescot, S. Giraud and X. Leyronas, Analytical theory of the dressed bound state in highly polarized Fermi gases, Europhys. Lett., 88 (2009) 60007 pdf
R. Combescot, F. Alzetto and X. Leyronas, Particle distribution and related energy formula, Phys. Rev. A 79, 053640 (2009) pdf
R. Combescot and X. Leyronas, Superfluid equation of state of cold fermionic gases in the Bose-Einstein regime, Phys. Rev. A 78, 053621 (2008) pdf
X. Leyronas and R. Combescot, Superfluid equation of state of dilute composite bosons, Phys. Rev. Lett. 99, 170402 (2007) pdf
R. Combescot, X. Leyronas and M.Yu. Kagan, Self-consistent theory for molecular instabilities in a normal degenerate Fermi gas in the BEC-BCS crossover, Phys. Rev. A. 73, 023618 (2006) [cond-mat/0507636] pdf

Fewbody physics
F. Alzetto, R. Combescot and X. Leyronas, Dimer-dimer scattering length for fermions with different masses: analytical study for large mass ratio, Phys. Rev. A 87, 022704 (2013) pdf
F. Alzetto, R. Combescot and X. Leyronas, Atom-dimer scattering for fermionic mixtures with different masses: s-wave and p-wave contributions, Phys. Rev. A 86, 062708 (2012) pdf
F. Alzetto, R. Combescot and X. Leyronas, Atom-dimer scattering length for fermions with different masses : analytical study of limiting cases, Phys. Rev. A 82, 062706 (2010) pdf
I.V. Brodsky, A. V. Klaptsov, M. Yu Kagan, R. Combescot and X. Leyronas, Exact diagrammatic approach for dimer-dimer scattering and bound states of three and four resonantly interacting particles, Phys. Rev. A 73, 032724 (2006) pdf
I.V. Brodsky, A. V. Klaptsov, M. Yu Kagan, R. Combescot and X. Leyronas, Bound states of three and four resonantly interacting particles, JETP Letters vol. 82, issue 5 , page 273-278 (2005) [cond-mat/0507240] pdf

Mesoscopic physics
C. Mora, P. Vitushinsky, X. Leyronas, A. A. Clerk, K. Le Hur, Theory of non-equilibrium transport in the SU(N) Kondo regime, Phys.Rev. B. 80, 155322 (2009) pdf
C. Mora, X. Leyronas and N. Regnault, Current noise through a Kondo quantum dot in a SU(N) Fermi liquid state, Phys. Rev. Lett. 100, 036604 (2008); Erratum : Phys. Rev. Lett. 102, 139902 (2009) pdf
X. Leyronas, P. G. Silvestrov and C. W. J. Beenakker, Scaling at the chaos threshold for interacting electrons in a quantum dot., Phys. Rev. Lett. 84, 3414 (2000) pdf
X. Leyronas, J. Tworzydlo and C. W. J. Beenakker, Non-Cayley tree model for quasiparticle decay in a quantum dot., Phys. Rev. Lett. 82, 4894 (1999) pdf

Collective modes
G.E. Astrakharchik, R. Combescot, X. Leyronas and S. Stringari, Equation of state and collective frequencies of a trapped Fermi gas along the BEC-unitarity crossover, Phys. Rev. Lett. 95, 030404 (2005) pdf
R. Combescot and X. Leyronas, Axial collective excitations of a degenerate Fermi gas in the BEC to unitar- ity crossover, Eur. Phys. Lett., 68 762-768 (2004) pdf
R. Combescot and X. Leyronas, Comment on Collective excitations of a degenerate gas at the BEC-BCS crossover, Phys. Rev. Lett. 93, 138901 (2004) pdf
X. Leyronas and R. Combescot, Instability of a trapped ultracold Fermi gas with attractive interactions: quantum effects, Eur. Phys. J. D 31, 493-497 (2004) pdf
J. N. Fuchs, X. Leyronas and R. Combescot, Hydrodynamic modes of a 1D trapped Bose gas, Phys. Rev. A 68, 043610 (2003) pdf
R. Combescot and X. Leyronas, Hydrodynamic modes in dense trapped ultracold gases, Phys. Rev. Lett. 89 190405 (2002) pdf

High Tc superconductors
R. Combescot and X. Leyronas, A simple theory for high Delta/Tc ratio in d-wave superconductors, Eur. Phys. J. B 23, 159-163 (2001) pdf
X. Leyronas and R. Combescot, Plane-Chain coupling in Y Ba2Cu3O7: Temperature dependence of the Pen- etration Depth, Physica C 290 (1997) 215-228 pdf
R. Combescot and X. Leyronas, Plane-Chain coupling in Y Ba2Cu3O7: Impurity effect on the critical tem- perature, Phys. Rev. B 54 (1996) 4320-4330 pdf
X. Leyronas and R. Combescot, London penetration depth of strongly coupled superconductors: Low-temperature behavior, Phys. Rev. B 54 (1996) 3482-3488 pdf
R. Combescot and X. Leyronas, Coupling between Planes and Chains in Y Ba2Cu3O7: A Possible Solution for the Order Parameter Controversy, Phys. Rev. Lett. 75 (1995) 3732- 3735 pdf

Excitons
M. Combescot, X.Leyronas and C. Tanguy, On the N-exciton normalization factor, Eur. Phys. J. B 31, 17-24 (2003) pdf
X. Leyronas and M. Combescot, Quantum wells, wires and dots with finite barrier: analytical expressions for the bound states, Solid State Communications 119 (2001) 631-635 pdf

Teaching

2012 - 2013
Master 2 ICFP (International Centre for Fundamental Physics): Condensed Matter Theory, lectures and TD
Master 2 ICFP: Superconductivity, TD
Master 1 UPMC: Preparation to the CAPES competitive exam for future highschool teachers, Thermodynamics
Licence 2 UPMC: Thermodynamics, lectures, TD and TP
Licence 1 UPMC: Introduction to Physics, TD

2011 - 2012
Master 2 ICFP (International Centre for Fundamental Physics): Condensed Matter Theory, lectures and TD
Master 2 ICFP: Superconductivity, TD
Master 1 UPMC: Preparation to the CAPES competitive exam for future highschool teachers, tutorat
Licence 2 UPMC: Thermodynamics, TD and TP
Licence 1 UPMC: Introduction to Physics, TD

Websites and informations

The Laboratoire de Physique Statistique is associated to the following organisations:

CNRS (UMR 8550)

Ecole Normale Supérieure

Université Paris VI

Université Paris VII