Modeling pre-invasive bronchial epithelial lesions

The growth of cancer cells involves many different processes which can only be captured by a complex model. However, simplified models provide a great deal of insight into the fundamental processes involved. In this workshop we proposed two simple models - one discrete stochastic model and one PDE modelto solve a 2-D simplification of the original problem

Atom-field transfer of coherence in a two-photon micromaser assisted by a classical field

We investigate the transfer of coherence from atoms to a cavity field initially in a statistical mixture in a two-photon micromaser arrangement. The field is progressively modified from a maximum entropy state (thermal state) towards an almost pure state (entropy close to zero) due to its interaction with atoms sent across the cavity. We trace over the atomic variables, i.e., the atomic states are not collapsed by a detector after they leave the cavity. We find that by applying an external classical driving field it is possible to substantially increase the field purity without the need of previously preparing the atoms in a superposition of their energy eigenstates. We also discuss some of the nonclassical features of the resulting field.Comment: 10 pages, 7 figures, LaTe

Transfer of coherence from atoms to mixed field states in a two-photon lossless micromaser

We propose a two-photon micromaser-based scheme for the generation of a nonclassical state from a mixed state. We conclude that a faster, as well as a higher degree of field purity is achieved in comparison to one-photon processes. We investigate the statistical properties of the resulting field states, for initial thermal and (phase-diffused) coherent states. Quasiprobabilities are employed to characterize the state of the generated fields.Comment: 20 pages, 8 figures, to appear in Journal of Modern Optic

Self-gravitating system made of axions

We show that the inclusion of an axion-like effective potential in the construction of a self-gravitating system made of scalar fields leads to a decrease on its compactness when the value of the self-interaction coupling constant is increased. By including the current values for the axion mass m and decay constant f_a, we have computed the mass and the radius for self-gravitating systems made of axion particles. It is found that such objects will have asteroid-size masses and radius of few meters, then, the self-gravitating system made of axions could play the role of scalar mini-machos that are mimicking a cold dark matter model for the galactic halo.Comment: 5 pages, 3 figures. References added. Accepted for publication in Physical Review

Coherence properties of coupled optomechanical cavities

In this work we investigate an optomechanical system consisting of two cavities coupled to the same mechanical resonator. We consider each cavity being weakly pumped as well as a small tunneling rate between the cavities. In such conditions, the system can be studied via quantum Langevin equations and the steady state solution can be found perturbatively. In order to ensure that the approximations and methods used to study the system are suitable, the analytical results were compared to numerical simulations. We study the statistical properties of the cavity radiation fields and we show that depending on the values of the parameters of the system, it is possible to modify the spectrum of the cavities and even enhance the sub-Poissonian character of the cavity field.Comment: 8 pages, 6 figure

A simple model for a minimal environment: the two-atom Tavis-Cummings model revisited

Individual quantum systems may be interacting with surrounding environments having a small number of degrees of freedom. It is therefore relevant to understand the extent to which such small (but uncontrollable) environments could affect the quantum properties of the system of interest. Here we discuss a simple system-environment toy model, constituted by a two-level atom (atom 1) interacting with a single mode cavity field. The field is also assumed to be (weakly) coupled to an external noisy subsystem, the small environment, modeled as a second two-level atom (atom 2). We investigate the action of the minimal environment on the dynamics of the linear entropy (state purity) and the atomic dipole squeezing of atom 1, as well as the entanglement between atom 1 and the field. We also obtain the full analytical solution of the two atom Tavis-Cummings model for both arbitrary coupling strengths and frequency detunings, necessary to analyze the influence of the field-environment detuning on the evolution of the above mentioned quantum properties. For complementarity, we discuss the role of the degree of mixedness of the environment by analyzing the time-averaged linear entropy of atom 1.Comment: Additional section and figure; references adde