Superiority of entangled measurements over all local strategies for the estimation of product coherent states

Niset J., Acin A., Andersen U. L., Cerf N. J., Garcia-Patron R., Navascues M., ...More

PHYSICAL REVIEW LETTERS, vol.98, no.26, 2007 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 98 Issue: 26
  • Publication Date: 2007
  • Doi Number: 10.1103/physrevlett.98.260404
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Dokuz Eylül University Affiliated: No


It is shown that the ensemble {P(alpha),vertical bar alpha >vertical bar alpha(*)>}, where P(alpha) is a Gaussian distribution of finite variance and |alpha > is a coherent state, can be better discriminated with an entangled measurement than with any local strategy supplemented by classical communication. Although this ensemble consists of products of quasiclassical states without any squeezing, it thus exhibits a purely quantum feature. This remarkable effect is demonstrated experimentally by implementing the optimal local strategy on coherent states of light together with a global strategy that yields a higher fidelity.