Generation of different Bell states within the SPDC phase-matching bandwidth

• Main Authors: Brida, G, Chekhova, M. V, Genovese, M, Krivitsky, L. A
• Format: Journal Article
• Language: English
• Published: 06-06-2007
• Subjects: Physics - Quantum Physics
• DOI: 10.48550/arxiv.0706.0848

Physical Review A 76, 053807 (2007) We study the frequency-angular lineshape 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.