Far-field resonance fluorescence from a dipole-interacting laser-driven cold atomic gas

We analyze the temporal response of the fluorescence light that is emitted from a dense gas of cold atoms driven by a laser. When the average interatomic distance is comparable to the wavelength of the photons scattered by the atoms, the system exhibits strong dipolar interactions and collective dissipation. We solve the exact dynamics of small systems with different geometries and show how these collective features are manifest in the scattered light properties such as the photon emission rate, the power spectrum and the second-order correlation function. By calculating these quantities beyond the weak (linear) driving limit, we make progress in understanding the signatures of collective behavior in these many-body systems. Furthermore, we shed light on the role of disorder and averaging on the resonance fluorescence, of direct relevance for recent experimental efforts that aim at the exploration of many-body effects in dipole–dipole interacting gases of atoms

Derivation of the Cramer-Rao Bound

I give a pedagogical derivation of the Cramer-Rao Bound, which gives a lower bound on the variance of estimators used in statistical point estimation, commonly used to give numerical estimates of the systematic uncertainties in a measurement

Derivation of the Quantum Mechanical Momentum Operator in the Position Representation

I pedagogically show that the momentum operator in quantum mechanics, in the position representation, commonly known to be a derivative with respect to a spatial x-coordinate, can be derived by identifying momentum as the generator of space translations

Quantum Field Theory: An Introduction

This document is a set of notes I took on QFT as a graduate student at the University of Pennsylvania, mainly inspired in lectures by Burt Ovrut, but also working through Peskin and Schroeder (1995), as well as David Tong’s lecture notes available online. They take a slow pedagogical approach to introducing classical field theory, Noether’s theorem, the principles of quantum mechanics, scattering theory, and culminating in the derivation of Feynman diagrams

Delayed Presentation of Congenital Diaphragmatic Hernia in the Emergency Department: Case Report

Introduction: Congenital diaphragmatic hernia (CDH) is an embryological defect of the diaphragm that typically presents in the neonatal period with respiratory distress.  However, delayed presentations do occur rarely and can pose diagnostic and therapeutic challenges. Case Report: We describe the case of a 9-month-old male who presented to the emergency department with respiratory distress and was subsequently diagnosed with congenital diaphragmatic hernia. Conclusion: This case underscores the importance of considering CDH in the differential diagnosis of pediatric patients presenting to the Emergency Department (ED) with unexplained respiratory or gastrointestinal symptoms, even beyond the neonatal period

A Critical Literacy Approach to Student Affairs Education

This article argues for the use of critical literacy as a critical pedagogy in student affairs practice. The authors describe how some currents of the student affairs literature have shifted toward a focus on student learning and critical approaches to student development and learning. Subsequently, they discuss the social turn in our understanding of literacy and a related move toward critical approaches to understanding literacy as a social practice. Finally, they present a synthesis of the literature, which results in considerations for approaching higher education student affairs contexts through a critical literacy framework, exposing gaps and areas for future theorizing and research

Inclusive search for same-sign dilepton signatures in pp collisions at root s=7 TeV with the ATLAS detector

An inclusive search is presented for new physics in events with two isolated leptons (e or mu) having the same electric charge. The data are selected from events collected from p p collisions at root s = 7 TeV by the ATLAS detector and correspond to an integrated luminosity of 34 pb(-1). The spectra in dilepton invariant mass, missing transverse momentum and jet multiplicity are presented and compared to Standard Model predictions. In this event sample, no evidence is found for contributions beyond those of the Standard Model. Limits are set on the cross-section in a fiducial region for new sources of same-sign high-mass dilepton events in the ee, e mu and mu mu channels. Four models predicting same-sign dilepton signals are constrained: two descriptions of Majorana neutrinos, a cascade topology similar to supersymmetry or universal extra dimensions, and fourth generation d-type quarks. Assuming a new physics scale of 1 TeV, Majorana neutrinos produced by an effective operator V with masses below 460 GeV are excluded at 95% confidence level. A lower limit of 290 GeV is set at 95% confidence level on the mass of fourth generation d-type quarks