Quantum information science asks what information processing tasks are possible if single quantum systems are used as elementary carriers of information. The ability to coherently manipulate the state of a quantum system allows for tasks that are thought to be unachievable in the classical context - such as inherently secure transmission of information - or for the efficient solution of computational problems for which no classical efficient algorithm is known. We ask - with methods of mathematical physics - questions of what manipulation of quantum information is possible. A recent emphasis has been to understand the precise computional power of quantum devices.

**Selected group publications**

- Architectures for quantum simulation showing a quantum speedup

Physical Review X 8, 021010 (2018) - Subsystem symmetries, quantum cellular automata, and computational phases of quantum matter

Quantum 3, 142 (2019) - Closing gaps of a quantum advantage with short-time Hamiltonian dynamics

arXiv:1908.08069 - Most quantum states are too entangled to be useful as computational resources

Physical Review Letters 102, 190501 (2009) - Novel schemes for measurement-based quantum computation

Physical Review Letters 98, 220503 (2007) - Precisely timing dissipative quantum information processing

Physical Review Letters 110, 110501 (2013) - Full randomness from arbitrarily deterministic events

Nature Communications 4, 2654 (2013) - Entanglement combing

Physical Review Letters 99, 130501 (2007) - Quantum measurement occurrence is undecidable

Physical Review Letters 108, 260501 (2012) - Matrix product operators and states: NP hardness and undecidability

Physical Review Letters 113, 160503 (2014) - Percolation, renormalisation, and quantum computing with non-deterministic gates

Physical Review Letters 100, 130501 (2007) - Full randomness from arbitrarily deterministic events

Nature Communications 4, 2654 (2013) - Quantitative entanglement witnesses

New Journal of Physics 9, 46 (2007) - Evenly distributed unitaries: On the structure of unitary designs

Journal of Mathematical Physics 48, 052104 (2007) - Gaussian quantum marginal problem

Communications in Mathematical Physics 280, 263 (2008) -
The complexity of relating quantum channels to master equations

Communications of Mathematical Physics 310, 383 (2012)

**Group reviews**

- Quantum coherence as a resource

Reviews of Modern Physics 89, 041003 (2017) - Multi-particle entanglement

In: Quantum Information Theory, Eds. D. Bruss, G. Leuchs (VCH, Weinheim, 2007) - Introduction to the basics of entanglement theory in continuous-variable systems

International Journal of Quantum Information 1, 479 (2003) - Quantum computing

In: Handbook of Nature-Inspired and Innovative Computing, Eds. Zomaya, G. Milburn et al (Springer, 2006) - Gaussian quantum channels

In: Continuous-variable quantum information science, Eds. E. Polzik, N. Cerf, G. Leuchs, (Imperial College Press, 2007) - Quantum information and percolation theory

In: Quantum percolation and breakdown (Springer, 2008)