Figure 3
From: Quantum Metrology: Surpassing the shot-noise limit with Dzyaloshinskii-Moriya interaction
Quantum Fisher information per particle for the Heisenberg model of two (blue) and three (red) qubits in the ferromagnetic (solid) and antiferromagnetic (dashed) regions.
Dotted line is for the shot-noise level of the separable states.
