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Quantum-dot spin-photon entanglement via frequency downconversion to telecom wavelength.

Authors
  • De Greve, Kristiaan
  • Yu, Leo
  • McMahon, Peter L
  • Pelc, Jason S
  • Natarajan, Chandra M
  • Kim, Na Young
  • Abe, Eisuke
  • Maier, Sebastian
  • Schneider, Christian
  • Kamp, Martin
  • Höfling, Sven
  • Hadfield, Robert H
  • Forchel, Alfred
  • Fejer, M M
  • Yamamoto, Yoshihisa
Type
Published Article
Journal
Nature
Publisher
Springer Nature
Publication Date
Nov 15, 2012
Volume
491
Issue
7424
Pages
421–425
Identifiers
DOI: 10.1038/nature11577
PMID: 23151585
Source
Medline
License
Unknown

Abstract

Long-distance quantum teleportation and quantum repeater technologies require entanglement between a single matter quantum bit (qubit) and a telecommunications (telecom)-wavelength photonic qubit. Electron spins in III-V semiconductor quantum dots are among the matter qubits that allow for the fastest spin manipulation and photon emission, but entanglement between a single quantum-dot spin qubit and a flying (propagating) photonic qubit has yet to be demonstrated. Moreover, many quantum dots emit single photons at visible to near-infrared wavelengths, where silica fibre losses are so high that long-distance quantum communication protocols become difficult to implement. Here we demonstrate entanglement between an InAs quantum-dot electron spin qubit and a photonic qubit, by frequency downconversion of a spontaneously emitted photon from a singly charged quantum dot to a wavelength of 1,560 nanometres. The use of sub-10-picosecond pulses at a wavelength of 2.2 micrometres in the frequency downconversion process provides the necessary quantum erasure to eliminate which-path information in the photon energy. Together with previously demonstrated indistinguishable single-photon emission at high repetition rates, the present technique advances the III-V semiconductor quantum-dot spin system as a promising platform for long-distance quantum communication.

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