Decoherence of wave packets in an anharmonic oscillator

Abstract

The time evolution of anharmonic molecular wave packets is investigated under the influence of the environment consisting of harmonic oscillators. These oscillators represent photon or phonon modes and assumed to be in thermal equilibrium. Our model explicitly incorporates the fact that in the case of a nonequidistant spectrum the rates of the environment induced transitions are different for each transition. The nonunitary time evolution is visualized by the aid of the Wigner function related to the vibrational state of the molecule. The time scale of decoherence is much shorter than that of dissipation, and gives rise to states which are mixtures of localized states along the phase space orbit of the corresponding classical particle. This behavior is to a large extent independent of the coupling strength, the temperature of the environment and also of the initial state.

Sub-Planck-scale structures in a vibrating molecule in the presence of decoherence

“…and H I is the interaction between the Morse particle and the environment, which we choose of the following form (see also [32,40])…”

“…Decoherence due to the coupling to an external environment is the main responsible for the disappearance of nonclassical manifestations of quantum states and it is considered one of the mechanisms through which the classical world at the macroscopic level emerges from the quantum substrate [28,29,30]. Decoherence on the molecular vibrational degree of freedom is due to the coupling between vibrational and rotational modes [31] and also to the coupling with the photonic and phononic degrees of freedom [32]. The latter are associated with a super-Ohmic environment describable in terms of a continuous set of bosonic modes and in this paper we shall focus on the effect of this source of decoherence.…”

Estimation of the spatial decoherence time in circular quantum dots

“…Technically, however, the degree of decoherence can be expressed through the density matrix of a quantum system, or, more precisely, through the damping of its off-diagonal elements 29,44,[54][55][56] . We shall adopt this definition in the following, although it is also possible to study decoherence directly in terms of the Wigner function 57 . The density matrix is connected to the Wigner function by the transformation…”

Scattering of accelerated wave packets

“…Floquet scattering is at the heart of some important physical effects, such as photon-assisted tunneling [14,32,33], quantum pumps [34][35][36][37], chaos-assisted tunneling [28,[38][39][40][41], coherent destruction of tunneling [8,42], quantum interference [43], Floquet-Fano resonances [17,31], field-induced barrier transparency [44,45], etc. Scattering from arbitrary time-periodic potentials or from stationary potentials with external non-periodic driving fields has received less attention so far [46][47][48][49][50][51][52][53][54]. The main reason is that the lack of time periodicity makes the scattering dynamics more involved, and in very few special cases an analytical treatment is available [47,50,51].…”