Quantum Physics

Protecting the quantum

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Science  27 Sep 2019:
Vol. 365, Issue 6460, pp. 1415-1416
DOI: 10.1126/science.365.6460.1415-c

Robust, fast, and with the capability of traveling vast distances, single photons are ideal carriers of quantum information. However, for on-chip applications, the photons inevitably interact with the surrounding medium and can be lost, which is perhaps even more true for delicate entangled photons where the nonclassical correlations between the photons can fizzle out. Recent developments have shown that topology can provide protection for photons and entangled photons against dissipation and disorder. Wang et al. demonstrate an integrated photonic chip approach in which the quantum correlations between two-photon states is given topological protection. A specially designed and fabricated photonic crystal provides topological boundary states within which the quantum correlations between entangled photons are maintained.

Optica 6, 955 (2019).

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