Lecture "Entanglement and locality in quantum many-body systems" (winter term 2014/15)
Lecturer: Norbert Schuch
(This is a mirror copy of the original course website at RWTH Aachen.)
Description
Interacting quantum many-body systems appear in all areas of physics, from condensed matter systems to high-energy physics. A characteristic feature of these systems is the local nature of their interactions. In the first part of this lecture, I will discuss the consequences of this locality, especially in the context of condensed matter systems. Most importantly, locality implies a finite propagation speed of excitations (the so-called Lieb-Robinson bounds), which have a number of remarkable consequences regarding the behavior of correlations, the stability of topological topological order, the classification of quantum phases, and the nature of the entanglement structure of these systems. The second part of the lecture will focus on the consequences of the specific entanglement structure of many-body systems. This covers in particular their description in terms of Tensor Network States, such as Matrix Product States and Projected Entangled Pair States, and the resulting class of simulation methods, most importantly the Density Matrix Renormalization Group (DMRG) algorithm. |
Material
Lecture notes
Further reading: W. Nolting and A. Ramakanth, Quantum Theory of Magnetism (Springer, 2009).
Further reading: [Hastings]; T. Koma and M.B. Hastings, Spectral gap and exponential decay of correlations;
R. Sims and B. Nachtergaele, Lieb-Robinson bounds and the exponential clustering theorem;
K. Fredenhagen, A Remark on the Cluster Theorem.
Further reading: [Hastings]; T. Koma and M.B. Hastings, Spectral gap and exponential decay of correlations;
R. Sims and B. Nachtergaele, Lieb-Robinson bounds and the exponential clustering theorem.
Further reading: [Hastings]; S. Bravyi, M.B. Hastings, and S. Michalakis, Topological quantum order: stability under local perturbations (Section 7).
Further reading: [Hastings]; M.B. Hastings and X.-G. Wen, Quasi-adiabatic Continuation of Quantum States: The Stability of Topological Ground State Degeneracy and Emergent Gauge Invariance;
S. Bravyi, M. B. Hastings, F. Verstraete, Lieb-Robinson bounds and the generation of correlations and topological quantum order.
Further reading: [Schuch].
Further reading: [Orus], [Schuch], [Schollwöck].
Further reading: sample DMRG code, and problems 3 and 4 in this exercise sheet.
Exercise sheets
Literature
Organisatorial issues
The lecture takes place Friday from 14:30 to 16:00 in room 26C401. Lecture notes will be posted on the course L2P site and this website. There is a bi-weekly exercise on Friday 16:00-17:30, as posted on the website. The exercise is voluntary. Examination will be though an oral exam of 30 mins. Please feel free to contact me if you have further questions. |