Quantum information meeting
From MPQTheory
Contents |
Current Activities
Past and future topics of the Quantum Information Meeting, held weekly, Thu 13:30h in the Theory Group Seminar Room B2.46.
Please add topics you'd like to hear discussed to the suggested topics.
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Schedule
- 26.01.
- 19.01.
- 12.01.
- 15.12. Joachim Schäfer (U Brussels): Information transmission through bosonic Gaussian memory channels
ABSTRACT: Bosonic Gaussian channels model common quantum channels, such as communication via free space or optical fibres. We show how to calculate the classical capacity for a Gaussian channel with memory, i.e. where the noise is correlated over successive uses of the channel. We find that the optimal input state is an entangled state which can be very well approximated by a Gaussian matrix product state (GMPS), which has a known experimental implementation. Finally, we define a class of correlated noises for which the GMPS is the exact optimal input state and furthermore, state the Hamiltonian for which the GMPS is known to be the ground state. This observation could suggest a link between problems in quantum communication and many body physics.
- 08.12. Piotr Sniady: You cannot win in a quantum casino
ABSTRACT: It is known that any quantum algorithm for "Graph Isomorphism Problem" that works within the framework of the "Hidden Subgroup Problem" (HSP) must perform highly entangled measurements across n \log n coset states. One of the only known models for how such a measurement could be carried out efficiently is Kuperberg's algorithm for the HSP in the dihedral group, in which quantum states are adaptively combined and measured according to the decomposition of tensor products into irreducible representations. This "quantum casino" starts with coset states, and works its way down towards representations whose probabilities differ depending on, for example, whether the hidden subgroup is trivial or nontrivial. I will show that such approach cannot produce a polynomial-time quantum algorithm for Graph Isomorphism.
- 01.12 Jian Cui: Local convertibility of quantum states in quantum critical systems
References: arXiv:1111.3537 and arXiv:1110.3331.
- 16.06 tba
- 09.06 tba
- 02.06 tba
- 26.05. group workshop Seefeld
- 19.05. no seminar (PhD defense Oliver)
- tba Fernando: tutorial on QEC (tbc)
Suggestions
- Michal Horodecki, Jonathan Oppenheim, Andreas Winter: Quantum mutual independence, arXiv:0902.0912.
please add topics, papers, preprints that you'd like to talk or hear about