Experimental Observation of Quantum Correlations in Modular Variables
  We experimentally detect entanglement in modular position and momentum variables of photon pairs which have passed through $D$-slit apertures. We first employ an entanglement criteria recently proposed in [Phys. Rev. Lett. {\bf 106}, 210501 (2011)], using variances of the modular variables. We then propose an entanglement witness for modular variables based on the Shannon entropy, and test it experimentally. Finally, we derive criteria for Einstein-Podolsky-Rosen-Steering correlations using variances and entropy functions. In both cases, the entropic criteria are more successful at identifying quantum correlations in our data. 
M. A. D. Carvalho, J. Ferraz, G. F. Borges, P. L. de Assis, S. P\'adua   and S. P. Walborn
quant-ph