Towards entanglement of very high orbital angular momentum
Robert Fickler (Fakultät für Physik Universität Wien)

Orbital angular momentum (OAM) of single photons represents a new optical degree of freedom for the entanglement of photons [1,2]. One physical realization of OAM carrying light beams are the so called Laguerre-Gaussian modes of light with the required helical phase structure. One big advantage over the well known polarization degree of freedom is the possibility of realizing entanglement between two photons with very high quantum numbers. However, the creation of photonic OAM entanglement using the widely used spontaneous parametric downconversion process is limited by the strongly reduced efficiency for higher momenta [3]. We investigate novel methods to create entanglement between two photons with a very high difference in their OAM quantum number and momentum respectively. Furthermore we explore hybrid entanglement of photons in the OAM and polarization degree of freedom.
Supported by ERC (Advanced Grant QIT4QAD) and the Austrian Science Fund (grant F4007).

[1] G. Molina-Terriza, J. P. Torres, L Torner, Nature Physics 3, 305 (2007)
[2] A. Mair, A. Vaziri, G. Weihs, A. Zeilinger, Nature 412, 313 (2001)
[3] B. Jack, J. Leach, H. Ritsch, S. M. Barnett, M. J. Padgett, S. Franke-Arnold, NJP 11, 103024 (2009)