Eur. Phys. J. D 13, 145-155 (2001)
https://doi.org/10.1007/s100530170295

Quantum decoherence from adiabatic entanglement with external one or a few degrees of freedom

¹ Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080, P.R. China
² Department of Physics,The Chinese University of Hong Kong, Hong Kong, P.R. China
³ Department of Mathematics, Peking University, Beijing, 100871, P.R. China

Corresponding author: ^a suncp@itp.ac.cn

Received: 26 February 2000
Revised: 14 July 2000
Published online: 15 January 2001

Abstract

Based on the Born-Oppenhemer approximation, the concept of adiabatic quantum entanglement is introduced to account for quantum decoherence of a quantum system due to its interaction with a large system of one or a few degrees of freedom. In the adiabatic limit, it is shown that the wave function of the total system formed by the quantum system plus the large system can be factorized as an entangled state with correlation between adiabatic quantum states and quasi-classical motion configurations of the large system. In association with a novel viewpoint about quantum measurement, which has been directly verified by most recent experiments [e.g., S. Durr et al., Nature 33, 359 (1998)], it is shown that the adiabatic entanglement is indeed responsible for the quantum decoherence and thus can be regarded as a "clean" quantum measurement when the large system behaves as a classical object. By taking the large system respectively to be a macroscopically distinguishable spatial variable, a high spin system and a harmonic oscillator with a coherent initial state, three illustrations are presented with their explicit solutions in this paper.