Discrete Tunable Color Entanglement

S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, A. Zeilinger

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100 Citations (Scopus)

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.

Original languageEnglish
Article number253601
Number of pages4
JournalPhysical Review Letters
Volume103
Issue number25
DOIs
Publication statusPublished - 18 Dec 2009

Keywords

  • QUANTUM COMMUNICATION
  • PHOTON PAIRS
  • INTERFERENCE
  • TIME
  • MOMENTUM
  • ENERGY
  • STATES

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