Laboratoire de Physique Théorique

de la Matière Condensée



Attention : désormais les séminaires ont lieu tous les lundis à 10h45 en salle  523 du LPTMC - Tour 12-13 


Assa Auerbach (Technion, Haifa, Israël)
What determines the Hall and Thermal Hall signs of metals, magnets and superconductors?

Christof Wetterich (ITP Heidelberg)
Quantum mechanics and quantum computation from classical bits

Riccardo Rossi (Flatiron Institute, New-York)
New diagrammatic Monte Carlo approches to the quantum many-body problem

Jacopo de Nardis (Université de Gand, Belgique)
Diffusion and super-diffusion in quantum and classical chains

Topological phases of quantum walks and how they can be detected

Janos Asboth (Wigner Research Centre for Physics & Budapest University, Hungary)

Quantum walks are versatile toy models for periodically driven systems in the nonperturbative regime of low-frequency and high-intensity drive. In this regime, systems can have "hidden" topological invariants: they can host topologically protected edge states even if their effective Hamiltonian is topologically trivial. I will discuss schemes we developed [1,2] to measure the bulk topological invariants, including the "hidden" ones, directly, which also work in the case with spatial disorder, and which have recently been measured in quantum walk experiments[3,4].

[1]: T Rakovszky, JK Asbóth, A Alberti: Detecting topological invariants in chiral symmetric insulators via losses, Phys Rev B 95 (20), 201407

[2]: B Tarasinski, JK Asbóth, JP Dahlhaus: Scattering theory of topological phases in discrete-time quantum walks, Phys Rev A 89 (4), 042327

[3]: Zhan, X., Xiao, L., Bian, Z., Wang, K., Qiu, X., Sanders, B.C., Yi, W. and Xue, P.: Detecting topological invariants in nonunitary discrete-time quantum walks. Phys Rev Lett, 119(13), 130501

[4]: S Barkhofen, T Nitsche, F Elster, L Lorz, A Gábris, I Jex, C Silberhorn: Measuring topological invariants in disordered discrete-time quantum walks, Phys Rev A 96 (3), 033846