Pulse-mode quantum projection synthesis: Effects of mode mismatch on optical state truncation and preparation

Quantum projection synthesis can be used for phase-probability-distribution measurement, optical-state truncation and preparation. The method relies on interfering optical lights, which is a major challenge in experiments performed by pulsed light sources. In the pulsed regime, the time frequency overlap of the interfering lights plays a crucial role on the efficiency of the method when they have different mode structures. In this paper, the pulsed mode projection synthesis is developed, the mode structure of interfering lights are characterized and the effect of this overlap (or mode match) on the fidelity of optical-state truncation and preparation is investigated. By introducing the positive-operator-valued measure (POVM) for the detection events in the scheme, the effect of mode mismatch between the photon-counting detectors and the incident lights are also presented.Comment: 11 pages, 4 figures, submitted to Phys. Rev.

Cross-cultural comparison of motor competence in children from Australia and Belgium

Motor competence in childhood is an important determinant of physical activity and physical fitness in later life. However, childhood competence levels in many countries are lower than desired. Due to the many different motor skill instruments in use, children’s motor competence across countries is rarely compared. The purpose of this study was to evaluate the motor competence of children from Australia and Belgium using the Körperkoordinationstest für Kinder (KTK). The sample consisted of 244 (43.4% boys) Belgian children and 252 (50.0% boys) Australian children, aged 6–8 years. A MANCOVA for the motor scores showed a significant country effect. Belgian children scored higher on jumping sideways, moving sideways and hopping for height but not for balancing backwards. Moreover, a Chi squared test revealed significant differences between the Belgian and Australian score distribution with 21.3% Belgian and 39.3% Australian children scoring “below average.” The very low levels reported by Australian children may be the result of cultural differences in physical activity contexts such as physical education and active transport. When compared to normed scores, both samples scored significantly worse than children 40 years ago. The decline in children’s motor competence is a global issue, largely influenced by increasing sedentary behavior and a decline in physical activity

Assessment of the applicability of failure frequency models for dense phase carbon dioxide pipelines

In Carbon Capture, Usage and Storage (CCUS) schemes, Carbon Dioxide (CO2) is captured from large scale industrial emitters and transported to geological sites for storage. The most efficient method for the transportation of CO2 is via pipeline in the dense phase. CO2 is a hazardous substance which, in the unlikely event of an accidental release, could cause people harm. To correspond with United Kingdom (UK) safety legislation, the design and construction of proposed CO2 pipelines requires compliance with recognised pipeline codes. The UK code PD-8010-1 defines the separation distance between a hazardous pipeline and a nearby population as the minimum distance to occupied buildings using a substance factor. The value of the substance factor should be supported by the results of a Quantitative Risk Assessment (QRA) approach to ensure the safe design, construction and operation of a dense phase CO2 pipeline. Failure frequency models are a major part of this QRA approach and the focus of this paper is a review of existing oil and gas pipeline third-party external interference failure frequency models to assess whether they could be applied to dense phase CO2 pipelines. It was found that the high design pressure requirement for a dense phase CO2 pipeline typically necessitates the use of high wall thickness linepipe in pipeline construction; and that the wall thickness of typical dense phase CO2 pipelines is beyond the known range of applicability for the pipeline failure equations used within existing failure frequency models. Furthermore, even though third party external interference failure frequency is not sensitive to the product that a pipeline transports, there is however a limitation to the application of existing UK fault databases with to onshore CO2 pipelines as there are currently no dense phase CO2 pipelines operating in the UK. Further work needs to be conducted to confirm the most appropriate approach for calculating failure frequency for dense phase CO2 pipelines, and it is recommended that a new failure frequency model suitable for dense phase CO2 pipelines is developed that can be readily updated to the latest version of the fault database

Gravitomagnetic Field of a Rotating Superconductor and of a Rotating Superfluid

The quantization of the extended canonical momentum in quantum materials including the effects of gravitational drag is applied successively to the case of a multiply connected rotating superconductor and superfluid. Experiments carried out on rotating superconductors, based on the quantization of the magnetic flux in rotating superconductors, lead to a disagreement with the theoretical predictions derived from the quantization of a canonical momentum without any gravitomagnetic term. To what extent can these discrepancies be attributed to the additional gravitomagnetic term of the extended canonical momentum? This is an open and important question. For the case of multiply connected rotating neutral superfluids, gravitational drag effects derived from rotating superconductor data appear to be hidden in the noise of present experiments according to a first rough analysis

Measuring the elements of the optical density matrix

Most methods for experimentally reconstructing the quantum state of light involve determining a quasiprobability distribution such as the Wigner function. In this paper we present a scheme for measuring individual density matrix elements in the photon number state representation. Remarkably, the scheme is simple, involving two beam splitters and a reference field in a coherent state.Comment: 6 pages and 1 figur

Teleportation-based number state manipulation with number sum measurement

We examine various manipulations of photon number states which can be implemented by teleportation technique with number sum measurement. The preparations of the Einstein-Podolsky-Rosen resources as well as the number sum measurement resulting in projection to certain Bell state may be done conditionally with linear optical elements, i.e., beam splitters, phase shifters and zero-one-photon detectors. Squeezed vacuum states are used as primary entanglement resource, while single-photon sources are not required.Comment: 9 pages, 4 figures, Misprints are corrected. 3 figures for number sum measurement are added. Discussion on manipulations are expanded. Calculations for success probabilities are added. Fig.4 is adde

Resonance fluorescence of a trapped three-level atom

We investigate theoretically the spectrum of resonance fluorescence of a harmonically trapped atom, whose internal transitions are $\Lambda$--shaped and driven at two-photon resonance by a pair of lasers, which cool the center--of--mass motion. For this configuration, photons are scattered only due to the mechanical effects of the quantum interaction between light and atom. We study the spectrum of emission in the final stage of laser--cooling, when the atomic center-of-mass dynamics is quantum mechanical and the size of the wave packet is much smaller than the laser wavelength (Lamb--Dicke limit). We use the spectral decomposition of the Liouville operator of the master equation for the atomic density matrix and apply second order perturbation theory. We find that the spectrum of resonance fluorescence is composed by two narrow sidebands -- the Stokes and anti-Stokes components of the scattered light -- while all other signals are in general orders of magnitude smaller. For very low temperatures, however, the Mollow--type inelastic component of the spectrum becomes visible. This exhibits novel features which allow further insight into the quantum dynamics of the system. We provide a physical model that interprets our results and discuss how one can recover temperature and cooling rate of the atom from the spectrum. The behaviour of the considered system is compared with the resonance fluorescence of a trapped atom whose internal transition consists of two-levels.Comment: 11 pages, 4 Figure

Validation of the NG-18 equations for thick walled pipelines

The applicability of the flow stress dependent NG-18 equations to thick wall pipelines such as those used to transport dense phase carbon dioxide (CO2) is demonstrated. A comparison between the components of the NG-18 equations and BS 7910 shows that the factor MT for though-wall defects and MP for part-wall defects in the NG-18 equations are very close to the reference stress solutions in BS 7910 Annex P, which are applicable to thick wall pipe. Thus, by inference, the flow stress dependent form of the NG-18 equations is also applicable to thick wall pipe. A further comparison with experimental failure data for thick wall pipes shows that the flow stress dependent NG-18 equations are applicable to wall thicknesses of up to 47.2 mm when the full-size equivalent upper shelf Charpy V-notch impact energy is at least 50 J. The results suggest that in principle, the flow stress dependent NG-18 equations may be used as limit state functions in models to calculate the failure frequency due to third party external interference, for high toughness, thick wall pipelines such as those required for dense phase CO2 pipelines

Squeezed states produced by modulation interaction and phase conjugation in fibers

Number-state expansions are derived for the squeezed states produced by four-wave mixing (modulation interaction and phase conjugation) in fibers. These expansions are valid for arbitrary pump-induced coupling and dispersion-induced mismatch coefficients. To illustrate their use, formulas are derived for the associated field-quadrature and photon-number variances and correlations

Robust Entanglement in Atomic Systems via Lambda-Type Processes

It is shown that the system of two three-level atoms in $\Lambda$ configuration in a cavity can evolve to a long-lived maximum entangled state if the Stokes photons vanish from the cavity by means of either leakage or damping. The difference in evolution picture corresponding to the general model and effective model with two-photon process in two-level system is discussed.Comment: 10 pages, 3 figure