Generation of ultrabright tunable polarization entanglement without spatial, spectral, or temporal constraints
Marco Fiorentino, Gaétan Messin, Christopher E. Kuklewicz, Franco N. C. Wong, Jeffrey H. Shapiro · Physical Review A · 2004
The need for spatial and spectral filtering in the generation of polarization entanglement is eliminated by combining two coherently driven type-II spontaneous parametric down-converters. The resulting ultrabright source emits photon pairs that are polarization entangled over the entire spatial cone and spectrum of emission. We detect a flux of $\ensuremath{\sim}12 000$ polarization-entangled pairs/s per mW of pump power at $90%$ quantum-interference visibility, and the source can be temperature tuned for $5\phantom{\rule{0.3em}{0ex}}\text{nm}$ around frequency degeneracy. The output state is actively controlled by precisely adjusting the relative phase of the two coherent pumps.