Line Plot from Scientific Research

QFI for the states shown in b, computed from the maximum likelihood reconstruction of the density matrix. The black dashed line indicates the theoretical value achieved by coherent states, representing the classical limit. The dashed turquoise and magenta lines indicate the experimental values achieved by a Fock |1> state and by the largest cat state from another work 20, respectively. The error bars are obtained by changing the Hilbert-space truncation by 2 in the maximum likelihood state reconstruction algorithm, which we note to be the dominant error source (that is, bigger than the imperfect axes calibration or Wigner background fluctuations).

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