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Q: Fachverband Quantenoptik und Photonik
Q 34: Quantum Information (Quantum Communication) I
Q 34.6: Vortrag
Mittwoch, 13. März 2019, 15:15–15:30, S HS 002 Chemie
Entanglement protection of high-dimensional states by adaptive optics — •Giacomo Sorelli1, Nina Leonhard2, Vyacheslav N. Shatokhin1, Claudia Reinlein2, and Andreas Buchleitner1 — 1Physikalisches Institut, Albert-Ludwigs-Universität Freiburg i. Br. — 2Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF, Jena
High-dimensional, discrete quantum systems (qudits) present several advantages over simple two-level systems (qubits). In particular, qudits increase the information encoded in a single carrier. Besides, high-dimensional bases result in stronger violations of Bell inequalities, which can enhance the security of entanglement-based quantum key distribution. Spanning a discrete, infinite-dimensional Hilbert space, photonic orbital angular momentum (OAM) states are suitable candidates for the realisation of such high-dimensional states. On the downside, the defining feature of OAM-carrying light beams, namely their helical wave front, is fragile with respect to turbulence induced phase distortions.
We consider the potential of adaptive optics (AO) to protect entanglement of high-dimensional OAM states against detrimental atmospheric effects. We show how AO is able to reduce crosstalk among the OAM modes, and consequently the entanglement decay as well as photon losses. Finally, a test of the AO-stabilised output state against high-dimensional Bell inequalities shows that the transmitted entanglement allows for secure communication, even under strong turbulence.