Relaxation methods complement variational and exact methods by providing bounds on observables (which are not attainable with variational methods) and offering favorable scaling compared to exact approaches. The core idea is to enlarge (relax) the set of so-called quantum moments, which are expectation values of operators acting on a many-body state.
Optimization problems over this new convex set can be solved efficiently without encountering local minima. While this approach has been applied in quantum many-body physics before, its utility for detecting phase transitions remains unexplored.
I show how this technique can be used to find all first- and second-order phase transitions of the transverse field Ising model and the frustrated bilayer Heisenberg model. Furthermore, I demonstrate how the latter changes when next-nearest neighbor intralayer interaction is introduced.
About the qGAP meeting series
Welcome to qGAP, our seminar series on Quantum Physics and Quantum Technology.
The series of seminars/lectures are meant to cover broadly activities at UiO and elsewhere related to quantum physics and technologies, mainly from a theoretical perspective, though we also welcome experimental talks.
We aim at having regular seminars, discussions of recent articles, presentations by master and PhD students and more. We aim for this series to be a combination of research talks and journal clubs.
Educational topics are also most welcome.
Please feel free to suggest speakers, yourself included!
Get in touch with Gunnar Lange to suggest a speaker or if you would like to be included in the mailing list.
All are welcome!