Weak values and the quantum phase space

We address the issue of how to properly treat, and in a more general setting, the concept of a weak value of a weak measurement in quantum mechanics. We show that for this purpose, one must take in account the effects of the measuring process on the entire phase space of the measuring system. By using coherent states, we go a step further than Jozsa in a recent paper, and we present an example where the result of the measurement is symmetrical in the position and momentum observables and seems to be much better suited for quantum optical implementation.Comment: 07 pages, accepted for PR

Results on a pedagogic approach for tailoring public health interventions to minimise opportunistic infections.

We are performing curriculum modifications on the first year BSc (Hons) Biomedical Science module “Basic Microbiology” (De Montfort University, UK) to increase students’ knowledge of basic medical parasitology and infectious diseases, so these students can acquire the necessary skills to tackle their final degree module “Medical Microbiology”. Following student feedback on a novel short intervention in 2017/18 to promote awareness about human immunodeficiency virus (HIV), we have created an engaging workshop session to cover not only HIV but also the opportunistic infections that can affect HIV patients that have developed acquired immune deficiency syndrome (AIDS) and how to prevent them. The objective of this work was to evaluate the effectiveness of the improved workshop developed and to collect students’ impressions to perform further modifications if needed. Briefly, students were required to develop public health measures for HIV positive patients with two different degrees of immunosuppression (i.e. with CD4+ T cells in peripheral blood above and below 200 cells/μl) to prevent exposure and infection from opportunistic pathogens such as Cryptosporidium spp., Toxoplasma gondii or Pneumocystis jirovecii from: a) sexual exposures; b) intravenous drug use; b) environment and work; c) food and water; d) foreign travel. Students, following evidence-based public health methodology, tailored their measures or interventions using the most up-to-date information reported in the literature regarding HIV chemoprophylaxis and recent guidelines published by US Department of Health and Human Services on HIV/AIDS treatment and prevention. Interventions were critically analysed with all students in the last 20 min. of the workshop, which was repeated several times due to the number of students (n=203). The objectives of this workshop were evaluated by careful analysis of a specific feedback questionnaire (n=46 out of 203) voluntarily completed by students at the end of the workshop. The questionnaire showed the following feedback: 80.4% (65.2% agreed; 15.2% strongly agreed) indicated that they learnt how to identify public health interventions; and 95.7% (56.5% agreed; 39.1% strongly agreed) indicated that they would be able to establish measures to reduce HIV transmission and prevent opportunistic infections. Additionally, 95.7% (39.1% agreed; 56.5% strongly agreed) indicated that the workshop helped them to understand the relevance of local and global interventions. Finally, 97.8% of responders considered that the content (52.2% agreed; 45.7% strongly agreed) and duration (60.9% agreed; 37% strongly agreed) of the workshop was appropriate; and 89.1% (58.7% agreed; 30.4% strongly agreed) and 73.9% (41.3% agreed; 32.6% strongly agreed) enjoyed and were satisfied with the workshop provided, respectively. In conclusion, the improved workshop developed would seem to be effective for promoting sexual and public health education to minimise opportunistic pathogen infections in relevant patients when delivered to students with a basic knowledge of microbiology and parasitology

Errors on the inverse problem solution for a noisy spherical gravitational wave antenna

A single spherical antenna is capable of measuring the direction and polarization of a gravitational wave. It is possible to solve the inverse problem using only linear algebra even in the presence of noise. The simplicity of this solution enables one to explore the error on the solution using standard techniques. In this paper we derive the error on the direction and polarization measurements of a gravitational wave. We show that the solid angle error and the uncertainty on the wave amplitude are direction independent. We also discuss the possibility of determining the polarization amplitudes with isotropic sensitivity for any given gravitational wave source.Comment: 13 pages, 4 figures, LaTeX2e, IOP style, submitted to CQ

Boltzmann equation simulation for a trapped Fermi gas of atoms

The dynamics of an interacting Fermi gas of atoms at sufficiently high temperatures can be efficiently studied via a numerical simulation of the Boltzmann equation. In this work we describe in detail the setup we used recently to study the oscillations of two spin-polarised fermionic clouds in a trap. We focus here on the evaluation of interparticle interactions. We compare different ways of choosing the phase space coordinates of a pair of atoms after a successful collision and demonstrate that the exact microscopic setup has no influence on the macroscopic outcome

On the optical conductivity of Electron-Doped Cuprates I: Mott Physics

The doping and temperature dependent conductivity of electron-doped cuprates is analysed. The variation of kinetic energy with doping is shown to imply that the materials are approximately as strongly correlated as the hole-doped materials. The optical spectrum is fit to a quasiparticle scattering model; while the model fits the optical data well, gross inconsistencies with photoemission data are found, implying the presence of a large, strongly doping dependent Landau parameter

Magnetic interactions in the Martensitic phase of Mn rich Ni-Mn-In shape memory alloys

The magnetic properties of Mn$_{2}$Ni$_{(1+x)}$In$_{(1-x)}$ ($x$ = 0.5, 0.6, 0.7) and Mn$_{(2-y)}$Ni$_{(1.6+y)}$In$_{0.4}$ ($y$ = -0.08, -0.04, 0.04, 0.08) shape memory alloys have been studied. Magnetic interactions in the martensitic phase of these alloys are found to be quite similar to those in Ni$_2$Mn$_{(1+x)}$In$_{(1-x)}$ type alloys. Doping of Ni for In not only induces martensitic instability in Mn$_2$NiIn type alloys but also affects magnetic properties due to a site occupancy disorder. Excess Ni preferentially occupies X sites forcing Mn to the Z sites of X$_2$YZ Heusler composition resulting in a transition from ferromagnetic ground state to a state dominated by ferromagnetic Mn(Y) - Mn(Y) and antiferromagnetic Mn(Y)-Mn(Z) interactions. These changes in magnetic ground state manifest themselves in observation of exchange bias effect even in zero field cooled condition and virgin magnetization curve lying outside the hysteresis loop.Comment: Accepted in J. Appl. Phy

Optical conductivity of URu2_2Si2_2 in the Kondo Liquid and Hidden-Order Phases

We measured the polarized optical conductivity of URu$_2$Si$_2$ from room temperature down to 5 K, covering the Kondo state, the coherent Kondo liquid regime, and the hidden-order phase. The normal state is characterized by an anisotropic behavior between the ab plane and c axis responses. The ab plane optical conductivity is strongly influenced by the formation of the coherent Kondo liquid: a sharp Drude peak develops and a hybridization gap at 12 meV leads to a spectral weight transfer to mid-infrared energies. The c axis conductivity has a different behavior: the Drude peak already exists at 300 K and no particular anomaly or gap signature appears in the coherent Kondo liquid regime. When entering the hidden-order state, both polarizations see a dramatic decrease in the Drude spectral weight and scattering rate, compatible with a loss of about 50 % of the carriers at the Fermi level. At the same time a density-wave like gap appears along both polarizations at about 6.5 meV at 5 K. This gap closes respecting a mean field thermal evolution in the ab plane. Along the c axis it remains roughly constant and it "fills up" rather than closing.Comment: 10 pages, 7 figure