Volume 87, Number 6, September 2009
Article Number 64003
Number of page(s) 5
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
Published online 09 October 2009
EPL, 87 (2009) 64003
DOI: 10.1209/0295-5075/87/64003

Characterization of spectral entanglement of spontaneous parametric-down conversion biphotons in femtosecond pulsed regime

G. Brida1, V. Caricato1, 2, M. V. Fedorov3, M. Genovese1, M. Gramegna1 and S. P. Kulik4

1   I.N.RI.M. - Istituto Nazionale di Ricerca Metrologica - Turin, Italy, EU
2   Dipartimento di Fisica, Politecnico di Torino - Turin, Italy, EU
3   A.M. Prokhorov General Physics Institute, Russian Academy of Science - Moscow, Russia
4   Faculty of Physics, M.V. Lomonosov Moscow State University - Moscow, Russia

received 4 June 2009; accepted in final form 12 September 2009; published September 2009
published online 9 October 2009

We verified the operational approach based on the direct measurement of the entanglement degree for bipartite systems. In particular spectral distributions of single counts and coincidence for pure biphoton states generated by a train of short pump pulses have been measured and the entanglement quantifier has been calculated. The approach gives an upper bound of entanglement stored in total biphoton states, which can reach extremely high values up to 104–105.

42.65.Lm - Parametric down conversion and production of entangled photons.
03.65.Ud - Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.).
03.67.Mn - Entanglement measures, witnesses, and other characterizations.

© EPLA 2009