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Phys. Rev. E 58, 6807–6809 (1998)

Wave function of a Brownian particle

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R. M. Cavalcanti*
Institute for Theoretical Physics, University of California, Santa Barbara, California 93106-4030

Received 5 May 1998; published in the issue dated November 1998

Using the Hamiltonian of Caldirola [Nuovo Cimento 18, 393 (1941)] and Kanai [Prog. Theor. Phys. 3, 440 (1948)], we study the time evolution of the wave function of a particle whose classical motion is governed by the Langevin equation mx¨+ηẋ=F(t). We show in particular that if the initial wave function is Gaussian, then (i) it remains Gaussian for all times, (ii) its width grows, approaching a finite value when t, and (iii) its center describes a Brownian motion and so the uncertainty in the position of the particle grows without limit.

© 1998 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevE.58.6807
DOI:
10.1103/PhysRevE.58.6807
PACS:
05.40.+j, 03.65.-w

*Electronic address: rmc@itp.ucsb.edu