May 05 2013

07.-09.05.2013 visit of Tanja Mehlstäubler

Tanja Mehlstäubler ( PTB Braunschweig) visits us and gives a talk about "Symmetry Breaking and Topological Defect Formation in Ion Coulomb Crystals" in the Ctrl-Q seminar on Wednesday 08.05.2013, 09.00 in E.04.

K. Pyka1, J. Keller1, H.L. Partner1, R. Nigmatullin2,3, T.
Burgermeister1, D.M. Meier1, K. Kuhlmann1, A. Retzker4, M.B.
Plenio2,3,5, W.H. Zurek6, A. del Campo6,7 & T.E. Mehlstäubler1

Structural defects in ion Coulomb crystals (kinks) have been proposed
for studies of quantum-mechanical effects with solitons and as
carriers of quantum information [1]. Defects form when a symmetry
breaking phase transition is crossed and the finite speed of
information prevents different regions from coordinating the choice of
the symmetry broken state. Where such local choices are incompatible,
defects will form with densities predicted to follow a power law
scaling in the rate of the transition. The importance of this
Kibble-Zurek mechanism (KZM) ranges from cosmology to condensed matter
[2-4]. In previous tests in homogeneous systems, defect formation was
seen, but weak dependence on the transition rate and limited control
of external parameters so far prevented tests of KZM scaling. As
recently predicted [5], in inhomogeneous systems propagation of the
critical front enhances the role of causality and steepens scaling of
defect density with the transition rate. We use ion Coulomb crystals
in a harmonic trap to demonstrate, for the first time, scaling of the
number of topological defects with the transition rate ? the central
prediction of KZM - in a well-controlled environment [6]. We will
detail on kink dynamics and stability in our system.

[1] Landa et al., Phys. Rev. Lett. 104, 043004 (2010)
[2] Kibble, T. W. B. Some implications of a cosmological phase
transition. Phys. Rep. 67, 183-199 (1980).
[3] Zurek, W. H. Cosmological experiments in superfluid helium? Nature
317, 505 (1985).
[4] Monaco, R., Mygind, J., Rivers, R. J., Koshelets, V. P.
Spontaneous fluxoid formation in superconducting
loops. Phys. Rev. B 80, 180501(R) (2009).
[5] del Campo, A., De Chiara, G., Morigi, G., Plenio, M. B., Retzker,
A. Structural Defects in Ion Chains by
Quenching the External Potential: The Inhomogeneous
Kibble-Zurek Mechanism. Phys. Rev. Lett. 105,
075701 (2010).
[6] Pyka et al., arXiv:1211.7005 (2012)

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