arXiv:2111.13864 · Probability and Mathematical Physics
Validity of Bogoliubov’s approximation for translation-invariant Bose gases
Morris Brooks, Robert Seiringer
Abstract
We verify Bogoliubov's approximation for translation invariant Bose gases in the mean field regime, i.e. we prove that the ground state energy $E_N$ is given by $E_N=Ne_\mathrm{H}+\inf σ\left(\mathbb{H}\right)+o_{N\rightarrow \infty}(1)$, where $N$ is the number of particles, $e_\mathrm{H}$ is the minimal Hartree energy and $\mathbb{H}$ is the Bogoliubov Hamiltonian. As an intermediate result we show the existence of approximate ground states $Ψ_N$, i.e. states satisfying $\langle H_N\rangle_{Ψ_N}=E_N+o_{N\rightarrow \infty}(1)$, exhibiting complete Bose--Einstein condensation with respect to one of the Hartree minimizers.