Discrete Tunable Color Entanglement

S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger
Phys. Rev. Lett. 103, 253601 – Published 16 December 2009

Abstract

Although frequency multiplexing of information has revolutionized the field of classical communications, the color degree of freedom (DOF) has been used relatively little for quantum applications. We experimentally demonstrate a new hybrid quantum gate that transfers polarization entanglement of nondegenerate photons onto the color DOF. We create, for the first time, high-quality, discretely color-entangled states (with energy band gap up to 8.4 THz) without any spectrally selective filtering, and unambiguously verify and quantify the amount of entanglement (tangle, 0.611±0.009) by reconstructing a restricted density matrix; we generate a range of maximally entangled states, including a set of mutually unbiased bases for an encoded qubit space. The technique can be generalized to transfer polarization entanglement onto other photonic DOFs, like orbital angular momentum.

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  • Received 30 April 2009

DOI:https://doi.org/10.1103/PhysRevLett.103.253601

©2009 American Physical Society

Authors & Affiliations

S. Ramelow1,2, L. Ratschbacher1, A. Fedrizzi1,2,3, N. K. Langford1,2, and A. Zeilinger1,2

  • 1Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
  • 2Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
  • 3Physics Department & Centre for Quantum Computer Technology, University of Queensland, Qld 4072, Australia

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Vol. 103, Iss. 25 — 18 December 2009

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