Hamburg 2009 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 60: Quanteneffekte: Dekohärenz

Q 60.6: Vortrag

Freitag, 6. März 2009, 11:45–12:00, VMP 6 HS-D

Emergence of pointer states in a non-perturbative environment — •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 superselection 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.

We study the emergence and dynamics of pointer states in the motion of a quantum test particle affected by collisional decoherence. We demonstrate that the complete set of pointer states is obtained by the solitonic solutions of the nonlinear equation suggested in [1]. They yield the expected probabilities, and 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. This result allows us to estimate the coherence length of atoms in interacting thermal gases.

[1] L. Diosi and C. Kiefer, Phys. Rev. Lett. 85, 3553 (2000).