Quantum Physics

Making a measure of quantum coherence

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Science  31 Oct 2014:
Vol. 346, Issue 6209, pp. 597
DOI: 10.1126/science.346.6209.597-d

The notion that particles have properties of waves lies at the heart of quantum mechanics. When quantum systems interact, their interaction can be described in terms of interfering waves, whose coherence is of utmost importance in working out how these waves ultimately interfere. Determining how much coherence there is in a system or how much is required for a particular process is difficult to quantify, though. Baumgratz et al. present a rigorous mathematical framework for the quantification of coherence and identify intuitive and easily computable measures that can be used to compute it. They argue that having such a quantifiable metric will have important implications for describing energy transfer processes or transferring quantum information between quantum elements.

Phys. Rev. Lett. 10.1103/PhysRevLett.113.140401 (2014).

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