QUIE2T Quantum Information Entanglement-Enabled Technologies

Device-Independent Quantum Information Processing represents a new paradigm for quantum information processing: the goal is to design protocols to solve relevant information tasks without relying on any assumption on the devices used in the protocol. For instance, protocols for device-independent key distribution aim at establishing a secret key between two honest users whose security is independent of the devices used in the distribution. Contrary to standard quantum information protocols, which are based on entanglement, the main resource for device-independent quantum information processing is quantum non-locality. Apart from the conceptual interest, device-independent protocols offer important advantages from an implementation point of view: being device-independent, the realizations of these protocols, though technologically challenging, are more robust against device imperfections. Current and near-future technology offer promising perspectives for the implementation of device-independent protocols.

This project explores all these fascinating possibilities. Its main objectives are (i) obtaining a better characterization of non-local quantum correlations from an information perspective, (ii) improve existing and derive new application of this resource for device-independent quantum information processing and (iii) design feasible implementations of device-independent protocols. We plan to tackle these questions with an inter-disciplinary approach combining concepts and tools from Theoretical and Experimental Physics, Computer Science and Information Theory.

The power of information theory – classical as well as quantum – originates in the abstraction of information from its physical carrier. On this level of discussion, every process, every time evolution and every operation is described by a quantum channel – an input-output relation abstracting from the microscopic origin of the physical dynamics. Quantum channels are therefore central objects and basic building blocks in quantum information theory. The composition of quantum channels is a very natural operation arising in most physical situations. Sequential composition arises, for instance, when two quantum processes are carried out one after the other. It is therefore surprising that a systematic study is still missing that analyses the effect of composition on basic properties of quantum channels, such as the ability to reliably transmit quantum information.

With this project we propose to fill this gap and provide a first in-depth analysis of fundamental properties of quantum channels, with a particular emphasis on the behaviour under sequential and parallel composition. We will, furthermore, initiate the study of complexity-theoretic properties of quantum channels, thereby providing a novel computer science perspective on quantum channels.

We expect the results from this project to have a profound impact to the study of quantum spin chains, quantum complexity theory and quantum cryptography. The project as well as the consortium is of interdisciplinary nature and will use modern tools from operator space theory, signal processing, convex geometry and complexity theory.