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We propose a scheme to generate and detect quantum coherence and quantum entanglement in a spin-1 Bose-Einstein condensate with the help of spin squeezing parameter and quantum Fisher information. It is shown that quantum coherence and quantum entanglement are independent of the Rabi frequency and the better entanglement can be achieved by increasing the number of atoms.

We present two schemes for dense coding with nonmaximally entangled cluster state via local measurement. The average amounts of information are unique from the different two schemes. The average amount of information transmitted from Alice to Bob depends not only on the measurement angle θ, but also on the superposition coefficients of the state. For a given nonmaximally entangled cluster state, the supervisor can control the average amount of information transmitted from the sender to the receiver by adjusting the measurement angle.

We investigate we investigate the quantum Fisher information and phase sensitivity in Yurke-like state superposed by two special multi-particle states and a symmetric state with relative phase. By studying the influences of superposition coefficients and relative phase on the maximal quantum Fisher information and phase sensitivity, we reveal some entanglement properties of Yurke-like state.