We study the frequency-angular line shape for a phase-matched nonlinear process producing entangled states and show that there is a continuous variety of maximally entangled states generated for different mismatch values within the natural bandwidth. Detailed considerations are made for two specific methods of polarization entanglement preparation, based on type-II spontaneous parametric down-conversion (SPDC) and on SPDC in two subsequent type-I crystals producing orthogonally polarized photon pairs. It turns out that different Bell states are produced at the center of the SPDC line and on its slopes, corresponding to about half-maximum intensity level. These Bell states can be filtered out by either frequency selection or angular selection, or both. Our theoretical calculations are confirmed by a series of experiments, performed for the two above-mentioned schemes of producing polarization-entangled photon pairs and with two kinds of measurements: frequency selective and angular selective.
Interference structure of two-photon amplitude revealed by dispersion spreading
G. Brida,
M. Genovese,
L. A. Krivitsky,
M. V. Chekhova
We study the interference structure of the second-order intensity correlation function for polarization-entangled two-photon light obtained from type-II collinear frequency-degenerate spontaneous parametric down conversion. The structure is visualized due to the spreading of the two-photon amplitude in an optical fiber with group-velocity dispersion. A birefringent material inserted at the output of the nonlinear crystal leads to a more complicated interference structure of the correlation function.
Quantum reconstruction of an intense polarization squeezed optical state
Ch. Marquardt,
J. Heersink,
R. Dong,
M. V. Chekhova,
A. B. Klimov,
L. L. Sanchez-Soto,
U. L. Andersen,
G. Leuchs
We perform a reconstruction of the polarization sector of the density matrix of an intense polarization squeezed beam starting from a complete set of Stokes measurements. By using an appropriate quasidistribution, we map this onto the Poincare space, providing a full quantum mechanical characterization of the measured polarization state.
Kontakt
Forschungsgruppe Maria Chekhova
Max-Planck-Institut für die Physik des Lichts Staudtstr. 2 91058 Erlangen
