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.
Superbroadcasting of conjugate quantum variables
Sacchi M F
2006
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.File in questo prodotto:
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