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We study quantum states produced by optimal phase covariant quantum cloners.We argue that cloned quantum superpositions are not macroscopic superpositionsin the spirit of Schr\"odinger's cat, despite their large particle number. Thisis indicated by calculating several measures for macroscopic superpositionsfrom the literature, as well as by investigating the distinguishability of thetwo superposed cloned states. The latter rapidly diminishes when consideringimperfect detectors or noisy states, and does not increase with the systemsize. In contrast, we find that cloned quantum states themselves aremacroscopic, in the sense of both proposed measures and their usefulness inquantum metrology with an optimal scaling in system size. We investigate theapplicability of cloned states for parameter estimation in the presence ofdifferent kinds of noise.

Are cloned quantum states macroscopic?