# Theory

The Groups research areas are Quantum Information Theory and its interface with many-body physics and quantum optics. Specifically, the Group has interest in the field of quantum information science is diversified in to various topics, which broadly include:

1. Characterizing and quantifying multipartite quantum correlations in finite as well as infinite quantum systems.

2. Connecting multipartite quantum correlations to different quantum information processing tasks.

3. Studying the properties and behavior of quantum correlations present in many-body quantum systems. The state describing the system can be static or dynamic ones, and the system can be ordered or disordered with respect to the system parameters.

4. Characterization and quantification of non-classicality in continuous variable quantum systems which are of interest in experimental quantum optics. And also to establish connection between such systems and their utility in several information theoretic protocols.

We also work on contemporary research interests in quantum information science and at the same time at its inter-disciplinary subjects.

History: Our group started out at the University of Erlangen-Nuremberg in 2001 (though it has roots to the Helsinki Institute of Physics from 1997), and relocated to the Institute of Quantum Computing at the University of Waterloo in 2006.

Our position in the research landscape: Our group explores the interface between quantum communication theory and quantum optical implementations.

we translate between abstract protocols (described by qubits) and physical implementations (described for example by laser pulses)

we benchmark implementations to properly characterize quantum advantage

we exploit quantum mechanical structures for use in quantum communication

Fields to which are group contributes:

Quantum Key Distribution: Theory for Applications

Quantum Repeater

Protocols with quantitative quantum advantage

Linear Optics

Entanglement Verification

Research Philosophy: As we work on our research topics, we also find often the need to extend the theoretical structures of quantum information theory to answer deeper underlying questions. These include for example which type of observed data can be turned into secret key? How to characterize symmetric extendibility of bi-partite quantum systems? How to verify entanglement from incomplete data in large Hilbert spaces?

When approaching a research question, it is our approach to concentrate on the development of tools, so that these tools answer the research question, and can also be used to answer other questions. This is in contrast to brute force methods that only solve the one problem at hand.

On our web pages you will be able to find more detailed information about our research outcomes, our current research direction and also about the opportunities to join our group.