Quantum Mechanics

Fine-tuning a quantum witness

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Science  07 Apr 2017:
Vol. 356, Issue 6333, pp. 38-39
DOI: 10.1126/science.356.6333.38-d

Quantum entanglement produces correlations between particles that cannot be described classically, and it is a resource sought out in many applications to leverage the quantum advantage over classical operation. However, determining whether particles are entangled is a complex process that can require a set of measurements (the witness) to establish the extent of the correlations between them. Shanhandeh et al. describe a protocol that should simplify the job of the witness somewhat. Using already known information about the systems, they demonstrate that entangled and unentangled states can be distinguished using fewer measurements. Extendable to larger systems, the simplified but enhanced witness should prove useful in quantum devices for which verifying entanglement is required.

Phys. Rev. Lett. 118, 110502 (2017).

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