Extended Data Figure 6.

Quantum Fisher information. Normalized quantum Fisher information for a Neel state (N = 15) with g/J₀ = 0.24 (white) and g/J₀ = 2.4 (blue), corresponding to the lowest and highest-gradient data in Fig. 2d. Points are experimental observations, with lines as guides to the eye. A value greater than one (dashed line) is an entanglement witness. After the initial fast dynamics up to tJ₀ ≈ 1, the QFI is consistent with saturation for the low gradient, and with slow entanglement growth for the high gradient, with behavior very similar to that previously observed in disordered MBL [28].