Interference pattern and visibility of a Mott insulator

We analyze theoretically the experiment reported in [F. Gerbier et al, cond-mat/0503452], where the interference pattern produced by an expanding atomic cloud in the Mott insulator regime was observed. This interference pattern, indicative of short-range coherence in the system, could be traced back to the presence of a small amount of particle/hole pairs in the insulating phase for finite lattice depths. In this paper, we analyze the influence of these pairs on the interference pattern using a random phase approximation, and derive the corresponding visibility. We also account for the inhomogeneity inherent to atom traps in a local density approximation. The calculations reproduce the experimental observations, except for very large lattice depths. The deviation from the measurement in this range is attributed to the increasing importance of non-adiabatic effects.Comment: 6 pages, 4 figure

Phase coherence of an atomic Mott insulator

We investigate the phase coherence properties of ultracold Bose gases in optical lattices, with special emphasis on the Mott insulating phase. We show that phase coherence on short length scales persists even deep in the insulating phase, preserving a finite visibility of the interference pattern observed after free expansion. This behavior can be attributed to a coherent admixture of particle/hole pairs to the perfect Mott state for small but finite tunneling. In addition, small but reproducible ``kinks'' are seen in the visibility, in a broad range of atom numbers. We interpret them as signatures for density redistribution in the shell structure of the trapped Mott insulator

Resonant control of spin dynamics in ultracold quantum gases by microwave dressing

We study experimentally interaction-driven spin oscillations in optical lattices in the presence of an off-resonant microwave field. We show that the energy shift induced by this microwave field can be used to control the spin oscillations by tuning the system either into resonance to achieve near-unity contrast or far away from resonance to suppress the oscillations. Finally, we propose a scheme based on this technique to create a flat sample with either singly- or doubly-occupied sites, starting from an inhomogeneous Mott insulator, where singly- and doubly-occupied sites coexist.Comment: 4 pages, 5 figure

Brain, language, and handedness: a family affair

The left planum temporale is a marker of left hemisphere language specialization. We investigated the effect of individual handedness and familial sinistrality on left planum temporale surface area and found the size is reduced in proportion with the number of left-handed immediate family members and is lowest when one's mother is left-handed. This reduction is independent of an individual's handedness or sex and has no counterpart in the right hemisphere

Using simulation for training and to change protocol during the outbreak of severe acute respiratory syndrome

INTRODUCTION: During the 2003 severe acute respiratory syndrome (SARS) crisis, we proposed and tested a new protocol for cardiac arrest in a patient with SARS. The protocol was rapidly and effectively instituted by teamwork training using high-fidelity simulation. METHODS: Phase 1 was a curriculum design of a SARS-specific cardiac arrest protocol in three steps: planning the new protocol, repeated simulations of this protocol in a classroom, and a subsequent simulation of a cardiac arrest on a hospital ward. Phase 2 was the training of 275 healthcare workers (HCWs) using the new protocol. Training involved a seminar, practice in wearing the mandatory personal protection system (PPS), and cardiac arrest simulations with subsequent debriefing. RESULTS: Simulation provided insights that had not been considered in earlier phases of development. For example, a single person can don a PPS worn for the SARS patient in 1 1/2 minutes. However, when multiple members of a cardiac arrest team were dressing simultaneously, the time to don the PPS increased to between 3 1/2 and 5 1/2 minutes. Errors in infection control as well as in medical management of advanced cardiac life support (ACLS) were corrected. CONCLUSION: During the SARS crisis, real-time use of a high-fidelity simulator allowed the training of 275 HCWs in 2 weeks, with debriefing and error management. HCWs were required to manage the SARS cardiac arrest wearing unfamiliar equipment and following a modified ACLS protocol. The insight gained from this experience will be valuable for future infectious disease challenges in critical care

Technical Model for Remediation (Workpackage 2.2)

The objective of this workpackage is the definition of the global remediation effort on a project. It defines strategies for upgrading quality through assessment and organization of the single remediation tasks as described in WorkPackage 2.1. The primary stance driving the remediation work in the Squale model is that quality should be increased incrementally. A remediation plan takes into account the defec- tive components as well as the violated practices. However, such a plan must also be effective and provide as much as improvements at the lowest cost. Different team cultures can come up with different ways to build a plan and split it in tasks between team members. It can involve technical architects, team leaders, and developers. The strategy to build the remediation plan is to be customized on a case-by-case basis

Technical and Economical Model (Workpackage 2.1)

The objective of this workpackage is to define a model for (i) assessing the effort of software modification, (ii) identifying healing actions following practices from the Squale quality model defined in the previous workpackage (WP1.3). It defines the input for the next workpackage which is about planning actions once their effort is characterized. The key constraints of this work are: • The remediation effort should be expressed in the context of a quality model. It should act as a quantification of the work to obtain a better (or good) quality of the entity under analysis. • The remediation should be based on practices as described in the workpackage 1.3

Quantum Spin Dynamics of Mode-Squeezed Luttinger Liquids in Two-Component Atomic Gases

We report on the observation of the phase dynamics of interacting one-dimensional ultracold bosonic gases with two internal degrees of freedom. By controlling the non-linear atomic interactions close to a Feshbach resonance we are able to induce a phase diffusive many-body spin dynamics. We monitor this dynamical evolution by Ramsey interferometry, supplemented by a novel, many-body echo technique. We find that the time evolution of the system is well described by a Luttinger liquid initially prepared in a multimode squeezed state. Our approach allows us to probe the non-equilibrium evolution of one-dimensional many-body quantum systems.Comment: 4 pages, 3 figures Updated version, minor change