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Q: Fachverband Quantenoptik und Photonik

Q 30: Poster II

Q 30.53: Poster

Tuesday, March 3, 2009, 16:30–19:00, VMP 9 Poster

Collisional-induced emergence of a pointer basis — •Marc Busse and Klaus Hornberger — Arnold Sommerfeld Center for Theoretical Physics, Ludwigs-Maximilians-Universität München

The influence of environmental degrees of freedom on a quantum system typically leads to a super-selection of a specific set of robust system states, called pointer states. Most characteristically, any superposition of these states gets rapidly mixed, while the only stable states are the pointer states themselves.

By using a specific unravelling of the master equation of collisional decoherence [1], we study the emergence and dynamics of pointer states in the motion of a quantum test particle in a gas environment. We demonstrate that the complete set of pointer states is obtained by the solitonic solutions of the nonlinear equation corresponding to the deterministic part of the orthogonal unravelling [2]. They move according to the corresponding classical equations of motion. In contrast to linear coupling models, the pointer basis turns out to be non-Gaussian, with a width determined by both the mean free path and the thermal de-Broglie wavelength of the gas environment. By analyzing the jump statistics of the orthogonal unravelling we further derive the statistical weights of the pointer states in the decohered ensemble, which are found to be given by their overlap with the initial state.

[1] K. Hornberger et. al., Phys. Rev. A 70, 053608 (2004).

[2] L. Diosi, Phys. Lett. 114A, 451 (1986).