Dresden 2026 – scientific programme

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QI: Fachverband Quanteninformation

QI 12: Quantum Foundations

QI 12.10: Talk

Wednesday, March 11, 2026, 17:45–18:00, BEY/0137

Multiple solutions of the classical shooting problem: consistent histories and decoherence — •Julian Rettenberger-Zweck and Juan-Diego Urbina — Institut für theoretische Physik, Universität Regensburg, Regensburg, Germany

The consistent histories approach to quantum mechanics [1] provides a framework for defining whether a sequence of events occurring at different times—a history—exhibits emergent classical behavior. Specifically, a set of histories is called consistent if the off-diagonal elements of the decoherence functional, which quantify the interference between histories, vanish in an appropriate limit, leaving only the (properly normalized) classical probabilities on the diagonal [2]. The semiclassical (Van Vleck–Gutzwiller) propagator [3] consists of a coherent sum over all classical paths—or, in the language of consistent histories, all classical histories satisfying the specified boundary conditions—which enables a direct calculation of the decoherence functional. In this way, we explicitly evaluate the decoherence functional for two simple systems: the particle on a circle and the particle in a box, confirming the suppression of interference between distinct classical histories as well as the effect of decoherence within a Caldeira–Leggett approach [4].

[1] R. B. Griffiths, J. Stat. Phys. 36, 219 (1984).

[2] H. F. Dowker and J. J. Halliwell, Phys. Rev. D 46, 1580 (1992).

[3] M. C. Gutzwiller, Chaos in Classical and Quantum Mechanics, Springer, New York (1990).

[4] A. O. Caldeira and A. J. Leggett, Physica A 121, 587 (1983).

Keywords: Consistent Histories; Semiclassics; Decoherence