Entanglement protection by adaptive optics

Mark M. Wilde, Todd A. Brun

Giacomo Sorelli, Nina Leonhard, Vyacheslav N Shatokhin +2 more

We theoretically study the potential of adaptive optics (AO) to protect entanglement of highdimensional photonic orbital-angular-momentum (OAM) states against turbulence-induced phase distortions.We demonstrate that AO is able to reduce crosstalk among the OAM modes and, consequently, the entanglement decay as well as photon losses.A test of the AO-stabilized output state against high-dimensional Bell inequalities shows that the transmitted entanglement allows for secure communication, even in the strong scintillation regime.

Anton Zeilinger, Herbert Joseph Bernstein, Daniel M. Greenberger +2 more

Kuntuo Zhu, Zaisheng Lin, Liuguo Yin +2 more

In this paper, we describe the study of the faithful propagation of entangled orbital angular momentum states of light under atmospheric turbulence. The spatial mode is encoded in the Ince-Gauss modes that constitute a complete family of exact and orthogonal solutions of the paraxial wave equation in an elliptic coordinate system. Adaptive optics is employed to protect the entanglement from degradation, in which the threshold of turbulence strength could be enhanced for a reliable entanglement distribution. We find that the evolution of entanglements relies on ellipticity and shows the opposite trend when adopting adaptive optics. The turbulence strengths, at which the concurrences of various entangled states become zero, are different without adaptive optics but almost the same with adaptive optics. The trace of the density matrix is independent of the different ellipticity with or without adaptive optics. We believe that this investigation is useful for long-distance quantum communications and quantum networks using orbital angular momentum as information carriers.

David S. Simon, Gregg S. Jaeger, Alexander V. Sergienko

Nina Leonhard, Giacomo Sorelli, Vyacheslav Shatokhin +2 more

Entanglement degradation of orbital-angular-momentum modes can be prevented using adaptive optics. The results prove the possibility of significantly reducing the crosstalk of modes, thereby making entanglement available even under moderate atmospheric turbulence conditions.