Quantum correlations in separable multi-mode states and in classically entangled light.

  title={Quantum correlations in separable multi-mode states and in classically entangled light.},
  author={Natalia Korolkova and Gerd Leuchs},
  journal={Reports on progress in physics. Physical Society},
  volume={82 5},
In this review we discuss intriguing properties of apparently classical optical fields, that go beyond purely classical context and allow us to speak about quantum characteristics of such fields and about their applications in quantum technologies. We briefly define the genuinely quantum concepts of entanglement and steering. We then move to the boarder line between classical and quantum world introducing quantum discord, a more general concept of quantum coherence, and finally a controversial… 

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