Entangling the Whole by Beam Splitting a Part

Callum Croal, Christian Peuntinger, Vanessa Chille, Christoph Marquardt, Gerd Leuchs, Natalia Korolkova, and Ladislav Mišta, Jr.
Phys. Rev. Lett. 115, 190501 – Published 4 November 2015

Abstract

A beam splitter is a basic linear optical element appearing in many optics experiments and is frequently used as a continuous-variable entangler transforming a pair of input modes from a separable Gaussian state into an entangled state. However, a beam splitter is a passive operation that can create entanglement from Gaussian states only under certain conditions. One such condition is that the input light is suitably squeezed. We demonstrate, experimentally, that a beam splitter can create entanglement even from modes which do not possess such a squeezing provided that they are correlated to, but not entangled with, a third mode. Specifically, we show that a beam splitter can create three-mode entanglement by acting on two modes of a three-mode fully separable Gaussian state without entangling the two modes themselves. This beam splitter property is a key mechanism behind the performance of the protocol for entanglement distribution by separable states. Moreover, the property also finds application in collaborative quantum dense coding in which decoding of transmitted information is assisted by interference with a mode of the collaborating party.

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  • Received 25 June 2015

DOI:https://doi.org/10.1103/PhysRevLett.115.190501

© 2015 American Physical Society

Authors & Affiliations

Callum Croal1, Christian Peuntinger2,3, Vanessa Chille2,3, Christoph Marquardt2,3, Gerd Leuchs2,3, Natalia Korolkova1, and Ladislav Mišta, Jr.4

  • 1School of Physics and Astronomy, University of Saint Andrews, North Haugh, Saint Andrews, Fife KY16 9SS, Scotland
  • 2Max Planck Institute for the Science of Light, Günther-Scharowsky-Straße 1/Building 24, D-91058 Erlangen, Germany
  • 3Institute of Optics, Information and Photonics, University of Erlangen-Nuremberg, Staudtstraße 7/B2, D-91058 Erlangen, Germany
  • 4Department of Optics, Palacký University, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic

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Issue

Vol. 115, Iss. 19 — 6 November 2015

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