ELFT HÍRADÓ

[tcsaba <tcsaba AT eik.bme.hu>]

                 M E G H Í V Ó - I N V I T A T I O N

    Seminar Series of the Department of Theoretical Physics at the
           Budapest University of Technology and Economics


                           András Pályi
                 (Department of Theoretical Physics,
         Budapest University of Technology and Economics)


    Poor man's topological quantum gate based on the 
Su-Schrieffer-Heeger model

Topological properties of quantum systems could provide protection of 
the encoded quantum information against environmental noise, and thereby 
drastically advance the potential of these setups in quantum information 
processing. Most proposals for topologically protected quantum gates are 
based on many-body systems, e.g., fractional quantum Hall states, exotic 
superconductors, or ensembles of interacting spins, bearing an inherent 
conceptual complexity. In this talk, I will propose and discuss a 
topologically protected quantum gate, based on a one-dimensional 
single-particle tight-binding model, known as the Su-Schrieffer-Heeger 
chain. The proposed Y gate acts in the two-dimensional zero-energy 
subspace of a Y junction assembled from three chains, and is based on 
the spatial exchange of the defects supporting the zero-energy modes. 
Using numerical results, I will demonstrate that the gate is robust 
against hopping disorder but is corrupted by disorder in the on-site 
energy. Then I will argue that this robustness is topological 
protection. This setup will most likely not lead to a practical quantum 
computer, nevertheless it does provide valuable insight to topological 
quantum computing as an elementary minimal model. Since this model is 
non-interacting and non-superconducting, its dynamics can be studied 
experimentally, e.g., using coupled optical waveguides.

Reference: Péter Boross, János K. Asbóth, Gábor Széchenyi, László 
Oroszlány, András Pályi, https://arxiv.org/abs/1902.01358


Időpont: 2019. február 15. péntek, 10:15
Helyszín: BME Fizikai Intézet, Elméleti Fizika Tanszék,
Budafoki út 8. F-épület, III lépcsőház, szemináriumi szoba