Eur. Phys. J. D (2015) 69: 151
https://doi.org/10.1140/epjd/e2015-60237-x

Regular Article

Exact time-dependent pointer state in a Jaynes-Cummings model with intensity-dependent level shift

¹ Department of Physics and Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210008, P.R. China
² Joint Center of Nuclear Science and Technology, Nanjing University, Nanjing 210093, P.R. China
³ Center of Theoretical Nuclear Physics, National Laboratoryof Heavy-Ion Accelerator, Lanzhou 730000, P.R. China

^a e-mail: zxonttguge@gmail.com

Received: 20 April 2015
Published online: 9 June 2015

Abstract

We show that in the Jaynes-Cummings model with an intensity-dependent level shift whose magnitude is tuned to give rise to periodic collapse and revival, there exists a kind of time evolution where the two-level system and a coherent boson field stay absolutely disentangled throughout the evolution, in spite of the nonzero interaction between them. This constitutes an explicit example for an exact time-dependent pointer state of the two-level system, which perhaps distinguishes this evolution from all known disentangled evolutions in JC-related models. The construction of such an evolution is made possible by a vast level degeneracy in the energy level structure. Two possible ways to observe this phenomenon are also discussed. We believe that the present work could contribute to the understanding of pointer states.