Motion of quantum systems under external time-periodic perturbation

A quantum particle in a periodical lattice under the effect of an external homogeneous field shows a periodical motion, usually a named Bloch oscillator, for long times. When we introduce a weak and slowly varying inhomogeneous field then the dynamics of the quantum particle still exhibits a periodical motion but with a different period and a different width of the interval of oscillation. In this paper we obtain a formula for the dominant terms of the perturbed period and width, then we apply our result to the study of the effect of Casimir–Polder forces to a vertical Bose–Einstein condensate trapped in an optical lattice.A quantum particle in a periodical lattice under the effect of an external homogeneous field shows a periodical motion, usually a named Bloch oscillator, for long times. When we introduce a weak and slowly varying inhomogeneous field then the dynamics of the quantum particle still exhibits a periodical motion but with a different period and a different width of the interval of oscillation. In this paper we obtain a formula for the dominant terms of the perturbed period and width, then we apply our result to the study of the effect of Casimir–Polder forces to a vertical Bose–Einstein condensate trapped in an optical lattice.

Journal of Physics A Mathematical and TheoreticalJun 11, 20084 citations

Time-dependent periodic perturbation of a two-level quantum system

David R. Dion

Jan 1, 19740 citations

Quantum system driven by rapidly varying periodic perturbation

Tasko P. Grozdanov, M. J. Raković

A quantum system driven by a high-frequency periodic perturbation is studied. By using the asymptotic expansions in terms of inverse powers of the driving frequency, a class of unitary time-dependent canonical transformations is defined which renders the transformed Hamiltonians time independent. One representative of those Hamiltonians is the quasienergy operator, which is explicitly derived up to the fourth order. The classical limit of the theory and the possibility of separating the mean-motion Hamiltonian is discussed. It is shown that this separation can consistently be carried out to higher orders only in the case of a uniform external force. The application of the method to unperturbed systems with regular confining and singular potentials is discussed by considering the examples of harmonic oscillator, particle in the double-well potential, and particle in the Coulomb potential.A quantum system driven by a high-frequency periodic perturbation is studied. By using the asymptotic expansions in terms of inverse powers of the driving frequency, a class of unitary time-dependent canonical transformations is defined which renders the transformed Hamiltonians time independent. One representative of those Hamiltonians is the quasienergy operator, which is explicitly derived up to the fourth order. The classical limit of the theory and the possibility of separating the mean-motion Hamiltonian is discussed. It is shown that this separation can consistently be carried out to higher orders only in the case of a uniform external force. The application of the method to unperturbed systems with regular confining and singular potentials is discussed by considering the examples of harmonic oscillator, particle in the double-well potential, and particle in the Coulomb potential.

Physical Review AAug 1, 198865 citations

Time-dependent Perturbations in Quantum Mechanics

Rainer Dick

Graduate texts in physicsJan 1, 20161 citation

Generalized Floquet theory for open quantum systems

C. M. Dai, Hong Li, W. Wang +1 more

For a periodically driven open quantum system, the Floquet theorem states that the time evolution operator $Λ(t,0)$ of the system can be factorized as $Λ(t,0)=\mathcal{D}(t)e^{\mathcal{L}_{eff}t}$ with micro-motion operator $\mathcal{D}(t)$ possessing the same period as the external driving, and time-independent operator $\mathcal{L}_{eff}$ . In this work, we extend this theorem to open systems that follow a modulated periodic evolution, in which the fast part is periodic while the slow part breaks the periodicity. We derive a factorization for the time evolution operator that separates the long time dynamics and the micro-motion for the open quantum system. High-frequency expansions for the effective evolution operator control the long time dynamics, and the micro-motion operator is also given and discussed. It may find applications in quantum engineering with open systems following modulated periodic evolution.For a periodically driven open quantum system, the Floquet theorem states that the time evolution operator $Λ(t,0)$ of the system can be factorized as $Λ(t,0)=\mathcal{D}(t)e^{\mathcal{L}_{eff}t}$ with micro-motion operator $\mathcal{D}(t)$ possessing the same period as the external driving, and time-independent operator $\mathcal{L}_{eff}$. In this work, we extend this theorem to open systems that follow a modulated periodic evolution, in which the fast part is periodic while the slow part breaks the periodicity. We derive a factorization for the time evolution operator that separates the long time dynamics and the micro-motion for the open quantum system. High-frequency expansions for the effective evolution operator control the long time dynamics, and the micro-motion operator is also given and discussed. It may find applications in quantum engineering with open systems following modulated periodic evolution.

arXiv:1707.05030Jul 17, 20174 citations

Time-dependent Perturbations in Quantum Mechanics

Rainer Dick

Graduate texts in physicsNov 25, 20112 citations

For a periodically driven open quantum system, the Floquet theorem states that the time evolution operator

Λ(t,0)

of the system can be factorized as

Λ(t,0)=\mathcal{D}(t)e^{\mathcal{L}_{eff}t}

with micro-motion operator

\mathcal{D}(t)

possessing the same period as the external driving, and time-independent operator

\mathcal{L}_{eff}

. In this work, we extend this theorem to open systems that follow a modulated periodic evolution, in which the fast part is periodic while the slow part breaks the periodicity. We derive a factorization for the time evolution operator that separates the long time dynamics and the micro-motion for the open quantum system. High-frequency expansions for the effective evolution operator control the long time dynamics, and the micro-motion operator is also given and discussed. It may find applications in quantum engineering with open systems following modulated periodic evolution.