Atomic Number Fluctuations in Spinor Bose–Einstein Condensate with Dynamical Quantum Phase Transitions

Abstract

We study atomic number fluctuations in a spinor Bose–Einstein condensate and use it to characterize behaviors of dynamical quantum phase transitions. We observe that the quench dynamics of the atomic number fluctuations exhibit a nonanalytical change with respect to a parameter in the final Hamiltonian and demonstrate that the atomic number fluctuations can be used to detect both the ground state phase diagram and the highest energy state quantum phase transition. We further analyze the dynamics of atomic number fluctuations for finite magnetization and show that the quantum fluctuations could also be used to probe the phase transitions of the highest energy level and the ground state.