Pulse shaping with birefringent crystals: a tool for quantum metrology

A method for time differentiation based on a Babinet-Soleil-Bravais compensator is introduced. The complex transfer function of the device is measured using polarization spectral interferometry. Time differentiation of both the pulse field and pulse envelope are demonstrated over a spectral width of about 100 THz with a measured overlap with the objective mode greater than 99.8%. This pulse shaping technique is shown to be perfectly suited to time metrology at the quantum limit

Precision measurements with photon-subtracted or photon-added Gaussian states

Photon-subtracted and photon-added Gaussian states are amongst the simplest non-Gaussian states that are experimentally available. It is generally believed that they are some of the best candidates to enhance sensitivity in parameter extraction. We derive here the quantum Cram\'er-Rao bound for such states and find that for large photon numbers photon-subtraction or -addition only leads to a small correction of the quantum Fisher information (QFI). On the other hand a divergence of the QFI appears for very small squeezing in the limit of vanishing photon number in the case of photon subtraction, implying an arbitrarily precise measurement with almost no light. However, at least for the standard and experimentally established preparation scheme, the decreasing success probability of the preparation in that limit exactly cancels the divergence, leading to finite sensitivity per square root of Hertz, when the duration of the preparation is taken into account.Comment: 19 pages, 3 figure

Performance tests with a 4.75 inch bore tapered-roller bearings at high speeds

The tapered-roller bearings were tested at speeds to 15,000 rpm which results in a cone-rib tangential velocity of 130 m/sec. (25,500 ft/min). Lubrication was applied either by jets or directly to the cone-rib, augmented with jets. Additional test parameters included thrust loads to 53,400 N (12,000 lbs), radial loads to 26,700 N (6,000 lbs), lubricant flow rates from 1.9 x 0.000 to 15.1 x 0.001 cubic meter/min. (0.5 to 4.0 gpm), and lubricant inlet temperatures of 350 K and 364 K (170 F and 195 F). Temperature distribution, separator speed, and drive-motor power demand were determined as functions of these test parameters

General Cram\'er-Rao bound for parameter estimation using Gaussian multimode quantum resources

Multimode Gaussian quantum light, including multimode squeezed and/or multipartite quadrature entangled light, is a very general and powerful quantum resource with promising applications to quantum information processing and metrology involving continuous variables. In this paper, we determine the ultimate sensitivity in the estimation of any parameter when the information about this parameter is encoded in such Gaussian light, irrespective of the exact information extraction protocol used in the estimation. We then show that, for a given set of available quantum resources, the most economical way to maximize the sensitivity is to put the most squeezed state available in a well-defined light mode. This implies that it is not possible to take advantage of the existence of squeezed fluctuations in other modes, nor of quantum correlations and entanglement between different modes. We show that an appropriate homodyne detection scheme allows us to reach this Cramr-Rao bound. We apply finally these considerations to the problem of optimal phase estimation using interferometric techniques

Real-time distance measurement immune from atmospheric parameters using optical frequency combs

We propose a direct and real-time ranging scheme using an optical frequency combs, able to compensate optically for index of refraction variations due to atmospheric parameters. This scheme could be useful for applications requiring stringent precision over a long distance in air, a situation where dispersion becomes the main limitation. The key ingredient is the use of a mode-locked laser as a precise source for multi-wavelength interferometry in a homodyne detection scheme. By shaping temporally the local oscillator, one can directly access the desired parameter (distance) while being insensitive to fluctuations induced by parameters of the environment such as pressure, temperature, humidity and CO$_2$ content

ANALYZING LINKAGES BETWEEN NURSERY FARM GROWTH RATES, STRUCTURAL VARIABLES, AND FIRM CHARACTERISTICS

Production of ornamental plants is one of agriculture's successes. However, concentration of production and retailing is occurring, bringing additional competitive pressure. An econometric model is used to explain growth rate using a cross-sectional data set from 2001, self-reported growth rates for nursery firms, and firm and operator characteristics.Production Economics,

Clustering Methods Assessment for Investment in Zero Emission Neighborhoods Energy System

This paper investigates the use of clustering in the context of designing the energy system of Zero Emission Neighborhoods (ZEN). ZENs are neighborhoods who aim to have net zero emissions during their lifetime. While previous work has used and studied clustering for designing the energy system of neighborhoods, no article dealt with neighborhoods such as ZEN, which have high requirements for the solar irradiance time series, include a CO2 factor time series and have a zero emission balance limiting the possibilities. To this end several methods are used and their results compared. The results are on the one hand the performances of the clustering itself and on the other hand, the performances of each method in the optimization model where the data is used. Various aspects related to the clustering methods are tested. The different aspects studied are: the goal (clustering to obtain days or hours), the algorithm (k-means or k-medoids), the normalization method (based on the standard deviation or range of values) and the use of heuristic. The results highlight that k-means offers better results than k-medoids and that k-means was systematically underestimating the objective value while k-medoids was constantly overestimating it. When the choice between clustering days and hours is possible, it appears that clustering days offers the best precision and solving time. The choice depends on the formulation used for the optimization model and the need to model seasonal storage. The choice of the normalization method has the least impact, but the range of values method show some advantages in terms of solving time. When a good representation of the solar irradiance time series is needed, a higher number of days or using hours is necessary. The choice depends on what solving time is acceptable.Comment: 12 pages, 19 figures, 7 tables, 1 Appendix

Understanding student engagement: Improving enrolments and grades in the high school Physics classroom

SCHOOL CONTEXT The College at which this investigation was completed is a suburban P-12 school, managed by Brisbane Catholic Education, Queensland, Australia.  While it is a fee-paying private school, the fees are relatively low, and is non-selective in terms of the academic ability of students.  It offers a broad curriculum offering that is similar to the local state high schools in the same catchment area. IMPROVING PHYSICS ENROLMENTS AND RESULTS Falling enrolments in secondary school mathematics and science is frequently identified as a concern in Australia.  In Queensland, typically less than 4% of the statewide Year 12 cohort complete Senior Physics (Queensland Tertiary Admissions Centre [QTAC], 2021).  Against this backdrop, The College, over the last 8 years, has increased the percentage of its senior cohort undertaking Senior Physics from less than 7% to consistently enrolling more than 20% in the last 3 years, with no students failing Physics since the introduction of the new Queensland Certificate of Education (QCE) syllabus in 2019.  Over this same period, enrolments at The College in other science and mathematics subjects of equivalent rigour have fallen or remained steady. A key element in the success has been applying an understanding of student engagement, as described in a model of engagement by Philip Schlechty (2011).  In Schlechty’s work, engagement is described as a spectrum with 5 distinct levels, measured against two dimensions of Attention and Commitment.  Student engagement measured in this way is not a characteristic of a student, but can vary from day to day depending on their environmental factors. In addition to identifying student engagement in this way, a framework of learning theories, teaching techniques (Schuh & Barab, 2008) and supportive processes focused on authenticity in learning (Lombardi, 2007) has been identified that can help to shift a student from one level of engagement to the next.  The positive results of this framework in terms of student engagement can be seen in the increase in enrolments and student success in what is seen as a difficult and challenging subject. REFERENCES Lombardi, M. M. (2007). Authentic Learning for the 21st Century: An Overview. In D. G. Oblinger (Ed.), EDUCASE Learning Initiative. Queensland Tertiary Admissions Centre (2021). QTAC ATAR Report 2021. Retrieved August 19th, 2022, https://www.qtac.edu.au/wp-content/uploads/2022/02/QTAC-ATAR-Report-2021.pdf Schlechty, P. (2011). Schlechty Centre on Engagement. Retrieved September 20, 2015, from Schlechty Centre: http://www.schlechtycenter.org/system/tool_attachment/4046/original/sc_pdf_engagement.pdf?1272415798 Schuh, K. L., & Barab, S. A. (2008). Philosophical Perspectives. In J. M. Spector, M. D. Merrill, J. v. Merrienboer, & M. P. Driscoll (Eds.), Handbook of Research on Educational Communications and Technology. Routlege