# Growth of Sobolev norms in the cubic defocusing nonlinear Schrödinger equation

### Marcel Guardia

Universitat Politècnica de Catalunya, Barcelona, Spain### Vadim Kaloshin

University of Maryland, College Park, United States

## Abstract

We consider the cubic defocusing nonlinear Schrödinger equation in the two dimensional torus. Fix $s>1$. Recently Colliander, Keel, Staffilani, Tao and Takaoka proved the existence of solutions with $s$-Sobolev norm growing in time.

We establish the existence of solutions with polynomial time estimates. More exactly, there is $c>0$ such that for any $\mathcal K\gg 1$ we find a solution $u$ and a time $T$ such that $\| u(T)\|_{H^s}\geq\mathcal K \| u(0)\|_{H^s}$. Moreover, the time $T$ satisfies the polynomial bound $0 < T < \mathcal K^c$.

## Cite this article

Marcel Guardia, Vadim Kaloshin, Growth of Sobolev norms in the cubic defocusing nonlinear Schrödinger equation. J. Eur. Math. Soc. 17 (2015), no. 1, pp. 71–149

DOI 10.4171/JEMS/499