Photonic Quantum Information Technology and the Foundations of Quantum Physics in Higher Dimensions

Final Report Summary - QIT4QAD (Photonic Quantum Information Technology and the Foundations of Quantum Physics in Higher Dimensions)

In the ERC Advanced Grant QIT4QAD, the group of Professor Zeilinger at the University of Vienna developed novel technologies for quantum information science, demonstrated new concepts for quantum computation and realized a number of fundamental experiments in quantum mechanics.

The work focused very much on quantum entanglement, a fundamental notion which Einstein called "spooky action at a distance". To implement quantum entanglement in more complex systems, the group developed new multiport devices and sources in fiber optics and integrated optics technology. Using these sources and multiports, the group was able to realize novel quantum correlations in higher-dimensional systems. These correlations are also called Einstein-Podolsky-Rosen correlations.

For future quantum computation, an important result was the achievement of a group of coherent single-photon upconversion experiments and the demonstration that using such techniques, quantum entanglement is preserved.

A possibly most interesting application is the first demonstration of blind quantum computation. This is the procedure that a central server in the future quantum internet can be operating in such a way that the operator of the server can never achieve any information about the tasks which he is performing for a client.

The group was also able to demonstrate quantum entanglement for the highest quantum numbers so far, and for unusually high quantum dimensions.

The most important fundamental experiments performed concern a demonstration that three-dimensional quantum systems cannot be understood on the basis of a classic-realistic way which is independent of the notion of quantum entanglement.

Further fundamental quantum experiments concerned so-called quantum erasure and delayed-choice experiments. There, one decides whether a photon behaves as a particle or a wave at a very late time, even after it has finished its travel.

The group also performed some novel test of Bell's inequality which proved that a local realistic interpretation of quantum mechanics is not possible.

Most recently, a novel quantum imaging technique was developed.

Final Report Summary - QIT4QAD (Photonic Quantum Information Technology and the Foundations of Quantum Physics in Higher Dimensions)

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