Berlin 2014 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 25: Quantum effects: Entanglement and decoherence II

Q 25.1: Talk

Tuesday, March 18, 2014, 14:00–14:15, DO24 1.101

Propagation of Orbital Angular Momentum Photons through Atmospheric Turbulence — •Nina Leonhard, Vyacheslav Shatokhin, and Andreas Buchleitner — Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Str. 3, 79104 Freiburg, Germany

Quantum information can be encoded into the wave fronts of photons carrying orbital angular momentum (OAM), where the Hilbert space is, in principle, of arbitrary dimension. As such, photons with OAM are very promising for free-space quantum communication. However, free-space links are intrinsically noisy due to atmospheric turbulence, causing distortion of the photon’s wave front and deterioration of quantum information. In this talk, we will discuss the impact of atmospheric turbulence on the bipartite entanglement of photonic OAM qudits using the phase screen model. In particular, we show that the entanglement of qubits (d=2), qutrits (d=3) and ququarts (d=4) vanishes at moderate values of the turbulence strength. Furthermore, we identify entangled states that are most robust against atmospheric turbulence. We show that with increasing turbulence strength, high-dimensional OAM states become rather fragile, and the maximally entangled effective qubits turn out to be the most robust states.