Eur. Phys. J. D 32, 391-396 (2005)
https://doi.org/10.1140/epjd/e2004-00190-3

Time-resolved homodyne characterization of individual quadrature-entangled pulses

Laboratoire Charles Fabry de l'Institut d'Optique, CNRS UMR 8501, 91403 Orsay, France

Corresponding author: ^a philippe.grangier@iota.u-psud.fr

Received: 29 September 2004
Published online: 21 December 2004

Abstract

We describe a simple and efficient set-up to generate and characterize femtosecond quadrature-entangled pulses. Quantum correlations equivalent to about 2.5 dB squeezing are efficiently and easily reached using the non-degenerate parametric amplification of femtosecond pulses through a single-pass in a thin (100 μm) potassium niobate crystal. The entangled pulses are then individually sampled to characterize the non-separability and the entropy of formation of the states. The complete experiment is analysed in the time-domain, from the pulsed source of quadrature entanglement to the time-resolved homodyne detection. This particularity allows for applications in quantum communication protocols using continuous-variable entanglement.