6,655 research outputs found

    The Born and Markov approximations for atom lasers

    Full text link
    We discuss the use of the Born and Markov approximations in describing the dynamics of an atom laser. In particular, we investigate the applicability of the quantum optical Born-Markov master equation for describing output coupling. We derive conditions based on the atomic reservoir, and atom dispersion relations for when the Born-Markov approximations are valid and discuss parameter regimes where these approximations fail in our atom laser model. Differences between the standard optical laser model and the atom laser are due to a combination of factors, including the parameter regimes in which a typical atom laser would operate, the different reservoir state which is appropriate for atoms, and the different dispersion relations between atoms and photons. We present results based on an exact method in the regimes in which the Born-Markov approximation fails. The exact solutions in some experimentally relavent parameter regimes give non-exponential loss of atoms from a cavity.Comment: 10 pages, 3 figures. (2 new figues). Exact solutions have been included in section II. Sections IV and V have been expanded. A new section discussing the effects of gravity has been include

    Stabilising entanglement by quantum jump-based feedback

    Full text link
    We show that direct feedback based on quantum jump detection can be used to generate entangled steady states. We present a strategy that is insensitive to detection inefficiencies and robust against errors in the control Hamiltonian. This feedback procedure is also shown to overcome spontaneous emission effects by stabilising states with high degree of entanglement.Comment: 5 pages, 4 figure

    Quantitative analysis of TM lateral leakage in foundry fabricated silicon Rib waveguides

    Get PDF
    We show that thin, shallow ridge, silicon-on-insulator waveguides exhibiting a lateral leakage behavior can be designed and fabricated using a standard silicon photonic foundry platform. We analyze the propagation loss through the observation of the transmitted TM polarized guided mode and TE polarized radiation and experimentally demonstrate that propagation losses as low as 0.087 dB/mm can be achieved. This demonstration will open a new frontier for practical devices exploiting a lateral leakage behavior with potential applications in the fields of biosensing and quantum optics among others

    Hope\u27s New Mexico 1997 Field Notes

    Get PDF

    Paired atom laser beams created via four-wave mixing

    Full text link
    A method to create paired atom laser beams from a metastable helium atom laser via four-wave mixing is demonstrated. Radio frequency outcoupling is used to extract atoms from a Bose Einstein condensate near the center of the condensate and initiate scattering between trapped and untrapped atoms. The unequal strengths of the interactions for different internal states allows an energy-momentum resonance which leads to the creation of pairs of atoms scattered from the zero-velocity condensate. The resulting scattered beams are well separated from the main atom laser in the 2-dimensional transverse atom laser profile. Numerical simulations of the system are in good agreement with the observed atom laser spatial profiles, and indicate that the scattered beams are generated by a four-wave mixing process, suggesting that the beams are correlated.Comment: 5 pages, 3 figure

    Information Systems Research Education in Australia: Continuing the Past or Gearing up for the Future

    Get PDF
    As the information systems discipline grows, so do the number of programs offering graduate research degrees (GRD). In Australasia these include one year post-graduate (honors) programs with research components, masters by research degrees, and doctorate degree programs. Graduate students entering their first research program are faced with a quantum leap in expectations and required skills. The burden is significant: they need to find a referent discipline, select a research method and paradigm, defend the research relevance, and fulfil the requirements of adding to a body of knowledge. The purpose of this paper is to inform discussion on the issue of graduate research skills. We identify the critical research skills needed and present two pragmatic models for teaching them. This provides a basis for a shared knowledge and discourse based on lessons learnt
    • …
    corecore