Thomas Dittrich

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We present a comprehensive account of directed transport in one-dimensional Hamiltonian systems with spatial and temporal periodicity. They can be considered as Hamiltonian ratchets in the sense that ensembles of particles can show directed ballistic transport in the absence of an average force. We discuss general conditions for such directed transport like(More)
The influence of periodic driving on coherent tunneling is investigated, using a quartic double-well potential in a monochromatic external field as a working example. Extensive numerical studies of the long-time behaviour of this system are combined with an analytical description on basis of the quasienergy formalism. Approximate solutions of the dynamics(More)
Using the parametrically driven harmonic oscillator as a working example, we study two different Markov-ian approaches to the quantum dynamics of a periodically driven system with dissipation. In the simpler approach, the driving enters the master equation for the reduced density operator only in the Hamiltonian term. An improved master equation is achieved(More)
We study the interplay between coherent transport by tunneling and diffusive transport through classically chaotic phase-space regions, as it is reflected in the Floquet spectrum of the periodically driven quartic double well. The tunnel splittings in the semiclassical regime are determined with high numerical accuracy, and the association of the(More)
  • Thomas Dittrich, Chen Menachem, Herzel Yamin, Lou Adams, Tadiran Batteries
  • 2011
Non-rechargeable batteries with a life of 20 years and more are required today for many smart metering and AMR applications in the US. Tadiran's non-rechargeable lithium thionyl chloride batteries offer a proven life of 25 years. Kohler's new touchless commercial faucet was designed to run even 30 years on a hybrid lithium battery. Similar requirements(More)
Chaotic tunneling in a driven double-well system is investigated in absence as well as in the presence of dissipation. As the constitutive mechanism of chaos-assisted tunneling, we focus on the dynamics in the vicinity of three-level crossings in the quasienergy spectrum. They are formed when a tunnel doublet, located on a pair of symmetry-related tori in(More)
We make use of the numerical simulation random walk (RWNS) method to compute the "jump" diffusion coefficient of electrons in nanostructured materials via mean-square displacement. First, a summary of analytical results is given that relates the diffusion coefficient obtained from RWNS to those in the multiple-trapping (MT) and hopping models. Simulations(More)
Nanoscale materials will play an important role in the development of future devices and applications. Among these materials, semiconductor nanocrystals (NCs) are attracting increasing interest due to their relatively easy preparation and the striking properties determined by quantum confinement. [1] There are several examples of the use of NCs in(More)