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Probabilistic cloning and identification of linearly independent quantum states

Lu-Ming Duan·Guang-Can Guo
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Abstract

We construct a probabilistic quantum cloning machine by a general unitary-reduction operation. With a postselection of the measurement results, the machine yields faithful copies of the input states. It is shown that the states secretly chosen from a certain set $\$=\left\{\left| Ψ_1\right> ,\left| Ψ_2\right> ,... ,\left| Ψ_n\right> \right\} $ can be probabilistically cloned if and only if $% \left| Ψ_1\right>$, $\left| Ψ_2\right>$, $... ,$ and $\left| Ψ_n\right>$ are linearly-independent. We derive the best possible cloning efficiencies. Probabilistic cloning has close connection with the problem of identification of a set of states, which is a type of $n+1$ outcome measurement on $n$ linearly independent states. The optimal efficiencies for this type of measurement are obtained.

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Lu-Ming Duan, Guang-Can Guo. 1998-04-27. Probabilistic cloning and identification of linearly independent quantum states. https://doi.org/10.1103/physrevlett.80.4999

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