Discording Power of Quantum Evolutions

被引：21

作者：

Galve, Fernando ^{[1
]}

Plastina, Francesco ^{[2
,3
]}

Paris, Matteo G. A. ^{[4
,5
]}

Zambrini, Roberta ^{[1
]}

机构：

[1] Inst Fis Interdisciplinar & Sistemas Complejos, CSIC, UIB, E-07122 Palma De Mallorca, Spain

[2] Univ Calabria, Dipartimento Fis, I-87036 Cosenza, Italy

[3] Ist Nazl Fis Nucl, Grp Collegato Cosenza, Milan, Italy

[4] Univ Milan, Dipartimento Fis, I-20133 Milan, Italy

[5] UdR Milano Statale, CNISM, I-20133 Milan, Italy

来源：

PHYSICAL REVIEW LETTERS | 2013年 / 110卷 / 01期

关键词：

STATES;

D O I：

10.1103/PhysRevLett.110.010501

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

We introduce the discording power of a unitary transformation, which assesses its capability to produce quantum discord, and analyze in detail the generation of discord by relevant classes of two-qubit gates. Our measure is based on the Cartan decomposition of two-qubit unitaries and on evaluating the maximum discord achievable by a unitary upon acting on classical-classical states at fixed purity. We find that there exist gates which are perfect discorders for any value of purity mu, and that they belong to a class of operators that includes the root 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. DOI:10.1103/PhysRevLett.110.010501

引用

页数：5

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