Adaptation of a Single-Electron Tight-Binding Representation for a Reduced-Density-Matrix Description of Optical Interactions

V. L. Jacobs

V. L. Jacobs, Alex Kutana

Abhishek Dhar, Keiji Saito, Peter Hänggi A

With this work we investigate the stationary nonequilibrium density matrix of current carrying nonequilibrium steady states of in-between quantum systems that are connected to reservoirs. We describe the analytical procedure to obtain the explicit result for the reduced density matrix of quantum transport when the system, the connecting reservoirs, and the system-reservoir interactions are described by quadratic Hamiltonians. Our procedure is detailed for both electronic transport described by the tight-binding Hamiltonian and for phonon transport described by harmonic Hamiltonians. For the special case of weak system-reservoir couplings, a more detailed description of the steady-state density matrix is obtained. Several paradigm transport setups for interelectrode electron transport and low-dimensional phonon heat flux are elucidated.

V. L. Jacobs

Rossen L. Pavlov, Alexander I. Kuleff, P. Tz. Yotov +1 more

Per Hedegård, A. O. Caldeira

The reduced density operator of a particle coupled to a fermionic environment (metal electrons) is written in terms of a Feynman-Vernon influence functional. Two different approaches are used in order to achieve this goal. Firstly, the environmental interacting electron gas is treated in RPA and the coupling is correctly accounted for up to second order in perturbation theory. Then the local and tight-binding models are studied. For the latter a second approach for obtaining the influence functional is used in the narrow-band limit. It is found that the popular representation of the environment in terms of a single set of harmonic oscillators is not feasible unless the particle is confined to move in a local region of radial extension r ≃ k F -1 .