Paper on discording power published in PRL

Good news for AQM. A new paper introducing the discording power of a unitary transformation has been just published in PRL. The paper reports the results of a collaboration of a group member (Matteo) with Francesco Plastina from Calabria University and Fernando Galve and Roberta Zambrini from University of Balearic Islands.

The discording power of a unitary transformation assesses its capability to produce quantum discord, and the Letter shows that exist gates which are optimal discorders for any value of purity and that they belong to a class of operators that includes the SWAP. Other gates, even those universal for quantum computation, do not posses the same property: the CNOT, for example, is a perfect discorder only for states with low or unit purity, but not for intermediate values. The discording power of a two-qubit unitary also provides a generalization of the corresponding measure defined for entanglement to any value of the purity.

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