Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom and Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore.
Phys Rev Lett. 2013 Feb 15;110(7):070502. doi: 10.1103/PhysRevLett.110.070502. Epub 2013 Feb 13.
Deep insight can be gained into the nature of nonclassical correlations by studying the quantum operations that create them. Motivated by this we propose a measure of nonclassicality of a quantum operation utilizing the relative entropy to quantify its commutativity with the completely dephasing operation. We show that our measure of nonclassicality is a sum of two independent contributions, the generating power--its ability to produce nonclassical states out of classical ones, and the distinguishing power--its usefulness to a classical observer for distinguishing between classical and nonclassical states. Each of these effects can be exploited individually in quantum protocols. We further show that our measure leads to an interpretation of quantum discord as the difference in superdense coding capacities between a quantum state and the best classical state when both are produced at a source that makes a classical error during transmission.
通过研究产生非经典相关性的量子操作，可以深入了解非经典相关性的本质。受此启发，我们提出了一种利用相对熵来量化量子操作与完全退相位操作的可交换性的量子操作非经典性度量。我们表明，我们的非经典性度量是两个独立贡献的总和，即产生能力——它将经典态转化为非经典态的能力，以及区分能力——它对经典观察者在区分经典态和非经典态方面的有用性。这些效应中的每一个都可以在量子协议中单独利用。我们进一步表明，我们的度量导致了量子失谐的解释，即当一个量子态和一个在传输过程中产生经典错误的源产生的最佳经典态之间的超密集编码容量的差异。
