Rupert Ursin (born January 26, 1973) is an Austrian experimental physicist active in the field of quantum entanglement and communications. He is currently deputy director at the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences. 
While studying experimental physics as an undergraduate in 1993, Ursin worked at the European Organization for Nuclear Research (CERN). Ursin completed his Masters diploma in 2001, then in December 2006 completed a PhD dissertation at University of Vienna on quantum teleportation over long distances. He continued with postdoctoral studies in 2007, and since 2013 has served as a research group leader at the IQOQI. 
Ursin's research group is active in the field of quantum entanglement and communications.
He has contributed to the foundations of quantum physics—demonstrating several examples of loophole-free Bell inequalities—and pioneering advances in quantum key distribution.
The group's interests include the intersection of gravity and quantum physics in microgravity and hypergravity experiments. Ursin also leads an international effort to bring a quantum physics experiment to the International Space Station (ISS) and develop quantum applications for space.
In 2012 Ursin joined an international collaboration with senior research scientist and commercial astronaut Christopher Altman to propose a novel demonstration of free-space quantum communications at an astronaut training base near the summit of the Mauna Kea volcano on the Big island of Hawaii.
Borne from collaborations initiated at the inaugural NASA Quantum Future Technologies Conference, the international team's collaborative proposal: Astronaut Development and Deployment of a Secure Space Communications Network was an invited submission to the NASA Institute for Advanced Concepts office,  then to the newly-created DARPA Quiness Macroscopic Quantum Communications program.      
In 2004, Rupert Ursin and several colleagues from the Institute for Experimental Physics at the University of Vienna succeeded in the world's-first demonstration of quantum teleportation of a photon outside of the laboratory, sending it a distance of 600 meters across the River Danube.
In 2007, Ursin succeeded in distributing entangled photons between the Canary Islands La Palma and Tenerife over a world-record distance of 144 km while working together in a collaboration with the European Space Agency (ESA). Other partners included the University of Munich, the University of Bristol and physicist Paolo Villoresi, who conducted the world's first demonstration of ground-to-space quantum communications, at the University of Padua.
As reported in Nature Communications on 22 August 2016, Ursin's group has successfully tested entanglement in accelerated reference frames.
- 2009 Christian-Doppler-Prize
- Rupert Ursin et al.: Quantum Teleportation across the Danube, Nature,430, 849 (2004).
- Rupert Ursin et al.: Entanglement-based quantum communication over 144 km, Nature Physics3, 481 - 486 (2007).
- Fink, M. et al . Experimental test of photonic entanglement in accelerated reference frames. Nat. Comm. 8, 15304 doi: 10.1038/ncomms15304 (2017).
- Anton Zeilinger Director, Austrian Academy of Sciences
- Christopher Altman NASA-trained commercial astronaut, Senio
- Research Scientist PISCES, DARPA QuIST
- DARPA Quiness Macroscopic quantum communications
- Quantum entanglement
- Quantum Experiments at Space Scale Austrian-Chinese parallel to Quiness