From classical to quantum stochastic processes.

In this paper, we construct quantum analogs starting from classical stochastic processes, by replacing random "which path" decisions with superpositions of all paths. This procedure typically leads to nonunitary quantum evolution, where coherences are continuously generated and destroyed. In spite of their transient nature, these coherences can change the scaling behavior of classical observables.

A generalized fidelity amplitude for open systems.

We consider a central system which is coupled via dephasing to an open system, i.e. an intermediate system which in turn is coupled to another environment.

Real-world impact of quitline interventions for provider-referred smokers.

Background: The healthcare provider-referral quitline model has potential to help identify and connect more smokers to effective cessation services as compared to the self-referral model alone. However, research is limited as to whether provider-referred smokers, who may have more barriers to quitting, can have similar rates of quit success using traditional quitline interventions as self-referred smokers.

Purpose: To (1) determine how provider-referred smokers may differ from self-referred smokers in their demographics, service utilization, and quit rates and (2) quantify the impact of traditional quitline services on provider-referred smokers' ability to quit.

Scattering approach to fidelity decay in closed systems and parametric level correlations.

Based on an exact analytical approach to describe scattering fidelity experiments [Köber et al., Phys. Rev.

Mode-resolved travel-time statistics for elastic rays in three-dimensional billiards.

We consider the ray limit of propagating ultrasound waves in three-dimensional bodies made from a homogeneous, isotropic, elastic material. Using a Monte Carlo approach, we simulate the propagation and proliferation of elastic rays using realistic angle-dependent reflection coefficients, taking into account mode conversion and ray splitting. For a few simple geometries, we analyze the long-time equilibrium distribution, focusing on the energy ratio between compressional and shear waves.

Microwave fidelity studies by varying antenna coupling.

The fidelity decay in a microwave billiard is considered, where the coupling to an attached antenna is varied. The resulting quantity, coupling fidelity, is experimentally studied for three different terminators of the varied antenna: a hard-wall reflection, an open wall reflection, and a 50 Ω load, corresponding to a totally open channel. The model description in terms of an effective Hamiltonian with a complex coupling constant is given.

Decoherence of an n-qubit quantum memory.

We analyze decoherence of a quantum register in the absence of nonlocal operations, i.e., n noninteracting qubits coupled to an environment.

Long-time signatures of short-time dynamics in decaying quantum-chaotic systems.

We analyze the decay of classically chaotic quantum systems in the presence of fast ballistic escape routes on the Ehrenfest time scale. For a continuous excitation process, the form factor of the decay cross section deviates from the universal random-matrix result on the Heisenberg time scale, i.e.

Anomalous slow fidelity decay for symmetry-breaking perturbations.

Symmetries as well as other special conditions can cause anomalous slowing down of fidelity decay. These situations will be characterized, and a family of random matrix models to emulate them generically presented. An analytic solution based on exponentiated linear response will be given.

Scattering fidelity in elastodynamics.

The recent introduction of the concept of scattering fidelity causes us to revisit the experiment by Lobkis and Weaver [Phys. Rev. Lett.

Experimental verification of fidelity decay: from perturbative to fermi golden rule regime.

The scattering matrix was measured for a flat microwave cavity with classically chaotic dynamics. The system can be perturbed by small changes of the geometry. We define the "scattering fidelity" in terms of parametric correlation functions of scattering matrix elements.

Low-rank perturbations and the spectral statistics of pseudointegrable billiards.

We present an efficient method to solve Schrödinger's equation for perturbations of low rank. The method is ideally suited for systems with short range interactions or quantum billiards. It involves a secular equation of low dimension, which directly returns the level counting function.

Signatures of the correlation hole in total and partial cross sections.

In a complex scattering system with few open channels, say a quantum dot with leads, the correlation properties of the poles of the scattering matrix are most directly related to the internal dynamics of the system. We may ask how to extract these properties from an analysis of cross sections. In general this is very difficult, if we leave the domain of isolated resonances.

Comment on "Models of intermediate spectral statistics".

In this Comment we point out that the semi-Poisson is well suited only as a reference point for the so-called "intermediate statistics," which cannot be interpreted as a universal ensemble, like the Gaussian orthogonal ensemble or the Poissonian statistics. In Ref. 2 it was proposed that the nearest-neighbor distribution P(s) of the spectrum of a Poissonian distributed matrix perturbed by a rank one matrix is similar to the semi-Poisson distribution.