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
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
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页数:5
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