If a third party tries to eavesdrop, the system immediately sounds the alarm — because entanglement is gone. You cannot intercept a quantum key without destroying it. That is not a feature. That is physics.
— Rupert UrsinRupert Ursin is the Founder and CEO of zerothird GmbH, a Vienna-based company commercialising entanglement-based quantum key distribution. He is also Deputy Director and Research Group Leader at IQOQI (Institute for Quantum Optics and Quantum Information) at the Austrian Academy of Sciences, where he has worked since 2013.
Ursin completed his PhD at the University of Vienna in 2006 under Nobel Prize laureate Anton Zeilinger, with research focused on quantum teleportation over long distances. Over the following two decades, his lab produced a series of landmark experiments that progressively moved quantum communication from controlled laboratory settings to real-world infrastructure.
In 2004, Ursin's team demonstrated the first quantum teleportation of a photon outside a laboratory — transmitting across 600 metres under the Danube River in Vienna. In 2007, they distributed entangled photons between the Canary Islands of La Palma and Tenerife over a world-record distance of 144 kilometres. In 2012, the team achieved quantum teleportation over 143 km with active feed-forward, published in Nature. These experiments established the scientific foundation for satellite-based quantum communication and put Vienna at the centre of the global quantum research map.
In 2015, Ursin co-authored a landmark loophole-free Bell inequality test, one of the most significant experimental confirmations in the history of quantum mechanics. He has been recognised in the Quantum 100 list of the world's most influential quantum technology figures and received the Christian-Doppler-Prize in 2009 and the Austrian Founder's Prize Phönix in 2023.
Founded in April 2023, zerothird GmbH is built on a distinctive approach to quantum key distribution. Rather than transmitting a key and hoping it is not intercepted, zerothird uses entangled photon pairs: keys are generated locally at each endpoint from correlated quantum measurements, and no key is ever sent over the network. Any eavesdropping attempt destroys the entanglement and is immediately detectable. The system offers a "Key-as-a-Service" model designed to protect critical infrastructure — from power grids and autonomous vehicles to financial systems and government communications — against both current threats and the future capabilities of quantum computers.
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