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Superbroadcasting of conjugate quantum variables

Giacomo M. D'Ariano·Paolo Perinotti·Massimiliano F. Sacchi
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Abstract

We consider the problem of broadcasting arbitrary states of radiation modes from N to M>N copies by a map that preserves the average value of the field and optimally reduces the total noise in conjugate variables. For N>=2 the broadcasting can be achieved perfectly, and for sufficiently noisy input states one can even purify the state while broadcasting--the so-called superbroadcasting. For purification (i.e. M<=N), the reduction of noise is independent of M. Similar results are proved for broadcasting with phase-conjugation. All the optimal maps can be implemented by linear optics and linear amplification.

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Giacomo M. D'Ariano, Paolo Perinotti, Massimiliano F. Sacchi. 2006-05-19. Superbroadcasting of conjugate quantum variables. https://doi.org/10.1209/epl%2Fi2006-10105-x

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