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[Fizinfo] Asbóth János előadása a BME-n

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  • From: Edina Szirmai <eszirmai AT>
  • To: Fizinfo AT
  • Subject: [Fizinfo] Asbóth János előadása a BME-n
  • Date: Wed, 25 Feb 2015 15:27:47 +0100
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az "Egzotikus Kvantum Fázisok" Lendület kutatócsoport
következő szemináriumára

Asbóth János
(MTA Wigner Fizikai Kutatóközpont)

Localization, Diffusion, Topological Phases in 2-D quantum walks

The hallmark property of Quantum Walks is that they spread ballistically,
<x^2> \propto t^2, faster than the diffusive, <x^2> \propto t spreading of
random walks. This gives them a "quantum speedup", which can be exploited
in quantum algorithms. In the presence of time-independent disorder,
however, 1- and 2-dimensional (1D and 2D) quantum walks are expected to
suffer Anderson localization, whereby their spread stops completely, <x^2>
\to \const, except for a few exceptions.

Simulating the 2D split-step Hadamard walk, we have found [1] that -
contrary to earlier simulation results [2] - it does not undergo Anderson
localization, instead, over long timescales, it spreads diffusively. We
explained this phenomenon by showing that this quantum walk is an iterative
dynamical system tuned to a critical point at a topological phase
transition. The role of the Chern number is here taken over[3] by the
Rudner invariant[4]. In the talk, I will explain this explanation.

[1]: J. M. Edge and J. K. Asboth, accepted to PRB,
[2]: J. Svozilik, R. D. J. Leon-Montiel, and J. P. Torres, PRA 86, 052327
[3]: J. K. Asboth and J. M. Edge, PRA 91, 022324 (2015)
[4]: M. S. Rudner, N. H. Lindner, E. Berg, and M. Levin, PRX 3, 031005

Az előadás helye: BME F III. épület, mfsz, szemináriumi szoba.
Ideje: 2015. március 2. hétfő, 14:15.

Minden érdeklődőt szeretettel várunk!

Szirmai Edina

Edina Szirmai
Department of Theoretical Physics,
Budapest University of Technology and Economics
Budafoki ut 8.
Budapest, Hungary
Tel:(+36-1) 463-4107
Fax:(+36-1) 463-3567

  • [Fizinfo] Asbóth János előadása a BME-n, Edina Szirmai, 02/25/2015

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