Interstellar laser communication would require targeting mirrors upwards of 50 - 100 meters in diameter to ensure the signal is received. Quantum entanglement could do away with the need for a line-of-sight transmission.

19. Juni 2003

Long-Distance Free-Space Distribution of Entangled Photons
(Science Express, June 19, 2003; Science Vol. 301, pp.621)
by Markus Aspelmeyer, Hannes R. Böhm, Tsewang Gyatso, Thomas Jennewein, Rainer
Kaltenbaek, Michael Lindenthal, Gabriel Molina-Terriza, Andreas Poppe, Kevin Resch, Michael Taraba, Rupert Ursin, Philip Walther, Anton Zeilinger

Demonstration of the distribution of quantum entanglement via optical free-space links to independent receivers separated by 600 m and without a line of sight between each other. A Bell inequality between those receivers is violated by more than 4 standard deviations confirming the quality of the entanglement. This outdoor experiment represents a step towards satellite-based distributed quantum entanglement.

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