Twin photons entangled in polarization and angular momentum

Nijil Lal, Sarika Mishra, Anju Rani +3 more

Geraldo A. Barbosa, H. H. Arnaut

A recent work [H. H. Arnaut and G. A. Barbosa, Phys. Rev. Lett. 85, 286 (2000)] has shown eigenstates describing pairs of photons from spontaneous parametric down-conversion, which are eigenstates of orbital, intrinsic, and total momentum. Experimental demonstration of transfer of angular momentum to parametric down-converted photons has also been achieved [A. Mair, A. Vaziri, G. Weihs, and A. Zeilinger, Nature 412, 313 (2001)]. This work shows conditions for phase matching and examples are given for a Laguerre-mode pump beam. Polar and azimuthal angles are connected by phase matching giving a peculiar divergence pattern for the down-converted light. Full entanglement of polarization and angular-momentum states of photons is discussed.

Alois Mair, Anton Zeilinger

Jorrit Visser, E. R. Eliel, Gerard Nienhuis

Polarization entanglement of twin photons created in the process of parametric down-conversion is fully determined by the pump polarization when the pump, signal, and idler beams are collinear with the symmetry axis of the nonlinear crystal. We point out that in this situation a threefold rotational symmetry is needed for the process to occur. We describe the polarization entanglement of the twin photons in terms of correlations on the Poincar\'e sphere. The inherent nonconservation of the intrinsic angular momentum of light in this process is discussed.

Alois Mair, Alipasha Vaziri, Gregor Weihs +1 more

Sonja Franke‐Arnold, Stephen Mark Barnett, Miles J. Padgett +1 more