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[Fizinfo] Asbóth János előadása a BME-n

Chronological Thread 
  • From: Andras Palyi <andraspalyi AT>
  • Subject: [Fizinfo] Asbóth János előadása a BME-n
  • Date: Thu, 3 Nov 2016 08:32:54 +0100

A BME-MTA Egzotikus Kvantumfázisok csoport következő szemináriuma:

Asbóth János (Wigner FK)
Spectral flow and winding of the gaps in the Hofstadter butterfly of Chern
and Floquet insulators

2016. november 8., kedd, 14:15
BME Elméleti Fizika Tanszék szemináriumi szobája (F épület, 3. lépcsőház,

“The Hofstadter butterfly[1] -- the spectrum of an electron hopping on a
square lattice in strong magnetic fields (Harper model) -- has inspired
researchers and played an instrumental role in the exploration of the quantum
Hall effect. One of its interesting features is that if the Fermi energy is
fixed in a topological gap, i.e., a gap with nonzero Chern index, the
fraction of occupied states can be changed by altering the magnetic field[2].
We rephrase this property as an energy eigenvalue flow across topological
gaps, and show that it applies to any lattice model. This includes the
Floquet spectra of periodically driven systems, also in the nonperturbative
regime of low frequency and high amplitude driving, where there is no simple
notion of occupied and unoccupied states. We show how the response of the
spectrum to a small change in the magnetic field gives us a simple way to
calculate the Rudner invariant[3].

[1]: D. R. Hofstadter, Phys. Rev. B 14, 2239–2249 (1976)
[2]: G. Wannier, physica status solidi (b) 88, 757 (1978)
[3]: M. S. Rudner et al, Phys. Rev. X 3, 031005 (2013)”

Minden érdeklődőt szeretettel várunk.

A szemináriumsorozat további programja:

Pályi András

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