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Q: Quantenoptik

Q 513: Quanteneffekte IV

Q 513.7: Talk

Friday, March 8, 2002, 15:30–15:45, HS 11/215

Angular EPR Paradox — •Sonja Franke-Arnold¹, Miles Padgett², and Stephen M. Barnett¹ — ¹Department of Physics and Applied Physics, University of Strathclyde, Glasgow, UK — ²Department of Physics and Astronomy, Glasgow, UK

In their famous paradox Einstein questioned the completeness of quantum mechanics by consideration of two particles entangled in their positions and momenta. Quantum mechanics forbids the simultaneous knowledge of these non-commuting. Einstein’s Gedankenexperiment seemed to indicate a way to overcome this by inferring the position or momentum of one particle by measurements performed on the other partner.

This original scheme has been most successfully applied to photon pairs generated by parametric down-conversion, and the entanglement in time, in transverse position and in spin polarisation has been studied. The same system is suitable for the study of entanglement between the orbital angular momentum and the emission angle of the emitted photons. We show by means of a simulation program that a measurement of the orbital angular momentum wipes out any information about the angular position of the same photon and vice versa. This is the angular analogue of the incompatibility of position and momentum measurements.