Dissipation induced coherence in partial condensate

Dissipation is unavoidable in quantum systems. It usually induces decoherences and changes quantum correlations. However in this work, we find that dissipation can be a tool to probe the coherence in the quantum gas. By introducing dissipation into a partial condensate of Rb87 through blue detuned light, we observe an oscillation of atom number between the condensate part and the non-condensate part before equilibrium state is reached. In addition, since these two parts have different loss rates under dissipation, total atom number after the dissipation also oscillates which indicates the coherence in the quantum gas. We also propose a model based on Bogoliubov theory and it shows qualitative consistence with our experimental result.