Dynamic squeezing in a single-mode boson field interacting with two-level system

Abstract

We studied the time evolution of a two-level electron system interacting with a single-mode bosonic field (i.e. photons, phonons). We found that in the adiabatic limit (i.e. electron motion fast and boson motion slow) it is possible to obtain a reduction in fluctuation for the position coordinate of boson and momentum coordinate as well, depending on the adiabatic potential. If the system is on a lower adiabatic sheet we obtain a reduction in momentum fluctuations. However, if the system is on an upper sheet the fluctuation in position coordinate (associated with the bosonic field) is reduced. The maximum reduction is for a range of parameters given by g(2)/vapproximate to1, where g is the electron-photon (phonon) coupling strength and 2v is the electron energy level splitting. Moreover, it is possible to generate squeezed light at a frequency different from the pump frequency. The output frequency is mainly given by the curvature of the adiabatic potential. The system is interesting because it can be implemented in nanoscale systems like a single or double quantum well system interacting with a laser field of radiation. The degree of squeezing can be improved either by time modulating the energy of the electron levels inside the quantum well or by modulating the laser field. (C) 2002 Elsevier Science B.V. All rights reserved.