Feshbach projection-operator partitioning for quantum open systems: Stochastic approach

Stochastic Feshbach Projection for the Dynamics of Open Quantum Systems.

We present a stochastic projection formalism for the description of quantum dynamics in bosonic or spin environments. The Schrödinger equation in the coherent state representation with respect to the environmental degrees of freedom can be reformulated by employing the Feshbach partitioning technique for open quantum systems based on the introduction of suitable non-Hermitian projection operato...

Projection Operator Approach to Constrained Systems

Recently, within the context of the phase space coherent state path integral quantisation of constrained systems, John Klauder introduced a reproducing kernel for gauge invariant physical states, which involves a projection operator onto the reduced Hilbert space of physical states, avoids any gauge fixing conditions, and leads to a specific measure for the integration over Lagrange multipliers...

Projection Operator Approach to Transport in Complex Single-Particle Quantum Systems

We discuss the time-convolutionless (TCL) projection operator approach to transport in closed quantum systems. The projection onto local densities of quantities such as energy, magnetization, particle number, etc. yields the reduced dynamics of the respective quantities in terms of a systematic perturbation expansion. In particular, the lowest order contribution of this expansion is used as a s...

Projection Operator in Adaptive Systems

The projection algorithm is frequently used in adaptive control and this note presents a detailed analysis of its properties.

Conservation law of operator current in open quantum systems