Dissipation-Assisted Coherence Formation in a Spinor Quantum Gas

We report the formation of magnetic eigenstates assisted by naturally occurring particle dissipation in a Bose-Einstein condensate of spin-2 ^{87}Rb atoms. Although the atomic interaction energetically favors the nonferromagnetic state, we observed the spontaneous evolution of an unpolarized spin state into the transverse ferromagnetic state. Under such dynamics, the spin-dependent dissipation of atoms enhances the synchronization of the relative phases among five magnetic sublevels to promote magnetization. Through numerical simulations based on mean-field theory, we show that another exotic magnetic eigenstate, the cyclic state, can also be formed through the spin-dependent dissipation of atoms.