Heinrich-Heine-Universität Düsseldorf, Institut für Theoretische Physik III, Germany.
Phys Rev Lett. 2012 Aug 3;109(5):050503. doi: 10.1103/PhysRevLett.109.050503. Epub 2012 Aug 1.
Quantum entanglement and quantum nonlocality are known to exhibit monogamy; that is, they obey strong constraints on how they can be distributed among multipartite systems. Quantum correlations that comprise and go beyond entanglement are quantified by, e.g., quantum discord. It was observed recently that for some states quantum discord is not monogamous. We prove, in general, that any measure of correlations that is monogamous for all states and satisfies reasonable basic properties must vanish for all separable states: only entanglement measures can be strictly monogamous. Monogamy of other than entanglement measures can still be satisfied for special, restricted cases: we prove that the geometric measure of discord satisfies the monogamy inequality on all pure states of three qubits.
量子纠缠和量子非局域性被认为具有单一性关系；也就是说，它们在多粒子系统中的分布受到严格限制。由量子纠缠扩展而来的量子关联可以用量子失谐等来定量描述。最近观察到，对于某些态，量子失谐不具有单一性关系。我们一般证明，对于所有态都具有单一性关系且满足合理基本性质的任何关联度量，对于所有可分态必须为零：只有纠缠度量才具有严格的单一性关系。对于特殊的受限情况，其他关联度量仍然可以满足单一性关系：我们证明，在所有三量子比特纯态上，几何失谐度量满足单一性关系不等式。
