Bernard Helffer (born 8 January 1949, Paris) is a French mathematician, specializing in

partial differential equation In mathematics, a partial differential equation (PDE) is an equation which imposes relations between the various partial derivatives of a Multivariable calculus, multivariable function. The function is often thought of as an "unknown" to be sol ...

s, spectral theory, and mathematical physics. He is the son of the pianist

Claude Helffer Claude Helffer (18 June 1922 – 27 October 2004) was a French pianist. Early life Helffer was born in Paris, and began piano lessons at the age of five and from the age of ten until the outbreak of World War II he studied with Robert Casa ...

and the musicologist Mireille Helffer. Helffer studied from 1968 at the

École Polytechnique École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

and received in 1976 from the

University of Paris-Sud Paris-Sud University (French: ''Université Paris-Sud''), also known as University of Paris — XI (or as Université d'Orsay before 1971), was a French research university distributed among several campuses in the southern suburbs of Paris, in ...

his doctorate under Charles Goulaouic with dissertation ''Hypoellipticité pour des classes d'opérateurs pseudodifférentiels à caractéristiques multiples''. From 1971 to 1978 he did research at

CNRS The French National Centre for Scientific Research (french: link=no, Centre national de la recherche scientifique, CNRS) is the French state research organisation and is the largest fundamental science agency in Europe. In 2016, it employed 31,637 ...

, from 1978 to 1989 he was a professor at the

University of Nantes The University of Nantes (french: Université de Nantes) is a public university located in the city of Nantes, France. In addition to the several campuses scattered in the city of Nantes, there are two satellite campuses located in Saint-Nazaire a ...

, and then he was a professor at the University Paris-Sud (and simultaneously taught for five years at the

École Normale Superieure École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

). His research in mathematical physics deals with statistical mechanics, liquid crystals, superconductivity, semiclassical approximation, and ground-state nodal lines in Laplace operators and Schrödinger operators. The

French Academy of Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV of France, Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific me ...

awarded Helffer in 1991 the ''Prix Langevin'' and in 2011 the ''Prix de l'État''. Helffer was from 1974 to 1978 the Secretary of the CNRS Mathematics Commission and from 1999 to 2004 a consultant for mathematics at the French Ministry of Education. From 2010 to 2012 he was the President of the

Société mathématique de France Lactalis is a French multinational dairy products corporation, owned by the Besnier family and based in Laval, Mayenne, France. The company's former name was Besnier SA. Lactalis is the largest dairy products group in the world, and is the sec ...

Selected publications

*with

Louis Boutet de Monvel Louis Boutet de Monvel (22 June 1941 – 25 December 2014) was a French mathematician who worked on functional analysis. He was a student of Laurent Schwartz in Paris and was professor at the Pierre and Marie Curie University. He was married to ...

and Alain Grigis: Parametrixes d'opérateurs pseudo-différentiels a caractéristiques multiples, Astérisque 34–35, 1976, pp. 93–121 *with Jean Nourrigat: Hypoellipticité maximale pour des opérateurs polynomes de champs de vecteurs, Birkhäuser 1985 *with Johannes Sjöstrand
Résonances en limite semi-classique
Mémoire SMF, Nr. 24–25, 1986 *Semi-classical analysis for the Schrödinger operator and applications, Springer 1988 *with Sjöstrand and P. Kerdelhué
Le papillon de Hofstadter revisité
Mémoire SMF, Nr. 43, 1990 *with Maria Hoffmann-Ostenhof, Thomas Hoffmann-Ostenhof, and Mark Owen: Nodal sets for groundstates of Schrödinger operators with zero magnetic field in non-simply connected domains, Comm. Math. Phys. 202 (1999), no. 3, 629–649. *with Abderemane Morame: "Magnetic bottles in connection with superconductivity." Journal of Functional Analysis 185, no. 2 (2001): 604–680.

World Scientific 2002 *with Francis Nier
Hypoelliptic estimates and spectral theory for Fokker-Planck operators and Witten Laplacians
Springer 2005 *with S. Fournais

Birkhäuser 2010

Cambridge Studies in Advanced Mathematics 139, 2013

References

External links

Bernard Helffer, Université Paris Sud, Département de Mathématiques
* {{DEFAULTSORT:Helffer, Bernard 1949 births Living people 20th-century French mathematicians 21st-century French mathematicians École Polytechnique alumni University of Paris alumni Academic staff of the University of Nantes Academic staff of the University of Paris