# Null-controllability of hypoelliptic quadratic differential equations

Abstract : We study the null-controllability of parabolic equations associated to a general class of hypoelliptic quadratic differential operators. Quadratic differential operators are operators defined in the Weyl quantization by complex-valued quadratic symbols. We consider in this work the class of accretive quadratic operators with zero singular spaces. These possibly degenerate non-selfadjoint differential operators are known to be hypoelliptic and to generate contraction semigroups which are smoothing in specific Gelfand-Shilov spaces for any positive time. Thanks to this regularizing effect, we prove by adapting the Lebeau-Robbiano method that parabolic equations associated to these operators are null-controllable in any positive time from control regions, for which null-controllability is classically known to hold in the case of the heat equation on the whole space. Some applications of this result are then given to the study of parabolic equations associated to hypoelliptic Ornstein-Uhlenbeck operators acting on weighted $L^2$ spaces with respect to invariant measures. By using the same strategy, we also establish the null-controllability in any positive time from the same control regions for parabolic equations associated to any hypoelliptic Ornstein-Uhlenbeck operator acting on the flat $L^2$ space extending in particular the known results for the heat equation or the Kolmogorov equation on the whole space.
Keywords :
Document type :
Journal articles

https://hal.archives-ouvertes.fr/hal-01301604
Contributor : Marie-Annick Guillemer <>
Submitted on : Tuesday, April 12, 2016 - 3:12:19 PM
Last modification on : Wednesday, March 27, 2019 - 4:10:22 PM

### Identifiers

• HAL Id : hal-01301604, version 1
• ARXIV : 1603.05367

### Citation

Karine Beauchard, Karel Pravda-Starov. Null-controllability of hypoelliptic quadratic differential equations. Journal de l'École polytechnique — Mathématiques, École polytechnique, 2018, 5, pp.1-43. ⟨hal-01301604⟩

Record views