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Coherence of an entangled exciton-photon state

Research output: Contribution to journalJournal article


  • A. J. Hudson
  • R. M. Stevenson
  • A. J. Bennett
  • R. J. Young
  • C. A. Nicoll
  • P. Atkinson
  • K. Cooper
  • D. A. Ritchie
  • A. J. Shields

Associated organisational unit

Article number266802
Journal publication date31/12/2007
JournalPhysical Review Letters
Number of pages4
Original languageEnglish


We study the effect of the exciton fine-structure splitting on the polarization entanglement of photon pairs produced by the biexciton cascade in a quantum dot. Entanglement persists despite separations between the intermediate energy levels of up to 4 mu eV. Measurements show that entanglement of the photon pair is robust to the dephasing of the intermediate exciton state responsible for the first-order coherence time of either single photon. We present a theoretical framework incorporating the effects of spin scattering, background light, and dephasing. We distinguish between the first-order coherence time, and a parameter which we measure for the first time and define as the cross-coherence time.