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Estimation of n non-identical unitary channels

Caleb J O'Loan
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Abstract

We investigate the simultaneous estimation of $n$ not necessarily identical unitary channels using multi-partite entanglement. We examine whether it is possible for the rate at which the mean square error decreases to be greater than that using the channels individually. For a reasonably general situation, in which there is no functional dependence between the channels, we show that this is not possible. We look at a case in which the channels are not necessarily identical but depend on a common variable. In this case, the mean square error decreases more rapidly using multi-partite entanglement.

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Caleb J O'Loan. 2008-02-08. Estimation of n non-identical unitary channels. https://arxiv.org/abs/0802.1181

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