Dahlem center for complex quantum systems

Preprints

BibTeX:

	@unpublished{nowforever,, title
	= {

Preprints
}, year =
	2030 }

Zhao Liu, Gunnar Möller and Emil J. Bergholtz
Lattice Genons
arXiv:1702.05115v1 [cond-mat.str-el].

[Abstract] [URL]

Abstract: Topological degeneracy is, together with fractionalization, the hallmark of topological order. While fractionalization has been demonstrated both theoretically and in laboratories leading to deep insights into our basic understanding of matter, there has been no corresponding success in tracking the evolution of ground-state degeneracy due to the lack of tractable microscopic models with arbitrarily tunable topology of space. In this work however, by computer simulations, we show that lattice versions of multicomponent fractional quantum Hall systems are novel playgrounds to fill this void. With wormhole-like defects that connect separated "universes" of different components, thus changing the global topology of space, we observe a nontrivial dependence of ground-state degeneracy on the number of defects, equivalent to adding exotic non-Abelian quasiparticles called "genons" proposed recently in terms of effective topological field theory. We identify a number of different lattice genons in both Abelian and non-Abelian phases, with quantum dimensions exceeding those of fundamental quasiparticles in the host states, and provide a promising platform to study their intriguing behavior.

BibTeX:

	@unpublished{1702.05115v1,
	author =
	Zhao Liu, Gunnar Möller and Emil J. Bergholtz, title
	= Lattice Genons, year =
	2017, note
	= arXiv:1702.05115v1 [cond-mat.str-el], url =
	http://arxiv.org/abs/1702.05115v1 }

Björn Sbierski, Maximilian Trescher, Emil J. Bergholtz and Piet W. Brouwer
Disordered double Weyl node: Comparison of transport and density-of-states calculations
arXiv:1606.06941 [cond-mat.mes-hall].

[Abstract] [URL]

Abstract: Double Weyl nodes are topologically protected band crossing points which carry chiral charge $\pm2$. They are stabilized by $C_{4}$ point group symmetry and are predicted to occur in $\mathrm{SrSi_{2}}$ or $\mathrm{HgCr_{2}Se_{4}}$. We study their stability and physical properties in the presence of a disorder potential. We investigate the density of states and the quantum transport properties at the nodal point. We find that, in contrast to their counterparts with unit chiral charge, double Weyl nodes are unstable to any finite amount of disorder and give rise to a diffusive phase, in agreement with predictions of Goswami and Nevidomskyy [Phys. Rev. B 92, 214504 (2015)] and Bera, Sau, and Roy [Phys. Rev. B 93, 201302(R) (2016)]. However, for finite system sizes a crossover between pseudodiffusive and diffusive quantum transport can be observed.

BibTeX:

	@unpublished{Sbierski2016a,
	author =
	Björn Sbierski, Maximilian Trescher, Emil J. Bergholtz and Piet W. Brouwer, title
	= Disordered double Weyl node: Comparison of transport and density-of-states calculations, year =
	2016, note
	= arXiv:1606.06941 [cond-mat.mes-hall], url =
	https://arxiv.org/abs/1606.06941 }

2017

BibTeX:

	@unpublished{20172018,, title
	= {

Preprints
}, year =
	2017 }

Kevin A. Madsen, Emil J. Bergholtz and Piet W. Brouwer
Josephson effect in a Weyl SNS junction
Phys. Rev. B 95(6), 064511 (2017).