Heisenberg limited Sagnac interferometry

We show how the entangled photons produced in parametric down conversion can be used to improve the sensitivity of a Sagnac interferometer. Two-photon and four-photon coincidences increases the sensitivity by a factor of two and four respectively. Our results apply to sources with arbitrary pumping and squeezing parameters.Comment: 11 pages, 5 figure

Recycling and the Environment: a Comparative Review Between Mineral-based Plastics and Bioplastics

Since their conception in the 1950s, mineral-based plastics have completely revolutionised our society with production reaching record highs year upon year. This cheap, and durable material has seen usage across a plethora of diverse industries and products, replacing traditional materials such as metals and wood. However, our reliance on mineral-based plastics has led to their improper disposal across the global, affecting our environments and ecosystems. As a response, different methods have been developed to help dispose of the large amounts of plastic waste produced, such as incineration or dumping in landfill sites, but these methods are not without their drawbacks including release of toxic substances into the air and leachate into the soil and waters respectively. Consequently, much interest is generated and channelled in recent years to the introduction of several types of biopolymers. These include plastics based on cellulosic esters, starch derivatives, polyhydroxybutyrate and polylactic acid. These biopolymers have been viewed as a suitable replacement for mineral-based plastics, and their production a good strategy towards sustainable development as they are mainly composed of biocompounds such as starch, cellulose and sugars. This short review article provides an overview as to whether biopolymers can rival mineral-based plastics considering properties such as mechanical strength, Young’s modulus and crystallinity and could they be regarded as a suitable material to reduce our reliance on mineral-based plastics, whilst simultaneously reducing non-renewable energy consumption and carbon dioxide emissions

Resolution of objects within subwavelength range by using the near field of a dipole

We analyze the far field resolution of apertures which are illuminated by a point dipole located at subwavelength distances. It is well known that radiation emitted by a localized source can be considered a combination of travelling and evanescent waves, when represented by the angular spectrum method. The evanescent wave part of the source can be converted to propagating waves by diffraction at the aperture thereby it contributes to the far field detection. Therefore one can expect an increase in the resolution of objects. We present explicit calculations showing that the resolution at the far zone is improved by decreasing the source-aperture distance. We also utilize the resolution enhancement by the near field of a dipole to resolve two closely located apertures. The results show that without the near field (evanescent field) the apertures are not resolved whereas with the near field of the dipole the far zone intensity distribution shows improved resolution. This method eliminates the requirements of near-field techniques such as controlling and scanning closely located tip detectors.Comment: 3 pages, 3 figure

Multi-reference approach to the calculation of photoelectron spectra including spin-orbit coupling

X-ray photoelectron spectra provide a wealth of information on the electronic structure. The extraction of molecular details requires adequate theoretical methods, which in case of transition metal complexes has to account for effects due to the multi-configurational and spin-mixed nature of the many-electron wave function. Here, the Restricted Active Space Self-Consistent Field method including spin-orbit coupling is used to cope with this challenge and to calculate valence and core photoelectron spectra. The intensities are estimated within the frameworks of the Dyson orbital formalism and the sudden approximation. Thereby, we utilize an efficient computational algorithm that is based on a biorthonormal basis transformation. The approach is applied to the valence photoionization of the gas phase water molecule and to the core ionization spectrum of the $\text{[Fe(H}_2\text{O)}_6\text{]}^{2+}$ complex. The results show good agreement with the experimental data obtained in this work, whereas the sudden approximation demonstrates distinct deviations from experiments

Karakterisasi Batuan Reservouir Pasir dengan Menggunakan Metode Hydraulic Flow Unit pada Sumur X

Pada ilmu logging, untuk mencari parameter berupa permeabilitas terdapat berbagai metode yangdinilai cukup akurat. Metode-metode yang biasa digunakan dalam mencari nilai permeabilitas antaralain adalah Timur, Tixier, Coates, dan Wylie-Rose. Pada perkembangannya terdapat metode baruyaitu metode Kozeny-Carman.Dengan metode Kozeny-Carman ini maka dikembangkan lagi suatumetode yang bernama HydraulicFlowUnit.Metode Hydraulic Flow Unit sendiri adalah suatu metodeyang menggabungkan antara atribut geologi batuan dengan data petrofisik yang ada sehingga akanmenghasilkan flow unit yang berbeda pada tiap batuan bergantung dari tekstur ataupunmineraloginya. Secara singkat HydraulicFlowUnit adalah pengelompokan batuan berdasar padaprinsip geologi dalam atribut aliran yang mengalir didalamnya. Pada tulisan ini perhitungan parameterpermeabilitas pada sumur “X” dengan Formasi Plover (gambar 1) menggunakan salah satu teoriberupa HydraulicFlowUnit. Dalam menentukan permeabilitas dengan menggunakan metodeHydraulic Flow Unit ini diperlukan data core yang berasal dari analisa core. Namun seperti yangdiketahui analisa core sendiri memakan biaya yang cukup banyak sehingga tidak setiap intervaldilakukan analisa core, oleh karena itu perlu dilakukan perhitungan permeabilitas pada intervalkedalaman yang tidak memiliki core. Untuk dapat menentukan permeabilitas pada interval kedalamanyang tidak memiliki core pada sumur “X”, terdapat metode statistik seperti Artificial NeuralNetwork.Metode ini tersedia pada software Interactive Petropyhsics. Dengan input data yang baikmaka perhitungan permeabilitas dapat dilakukan. Pada tulisan ini metode yang digunakan untukmencari parameter permeabilitas pada interval tidak ada core adalah metode Hydraulic Flow Unityang dibantu dengan metode statistik Artificial Neural Network. Penggunaan metode perhitunganpermeabilitas lainnya yaitu Timur dan Tixier dilakukan pula pada sumur “X”. Kedua metode empiris ininantinya akan di komparasi dengan metode Hydraulic Flow Unit terhadap sampel data core yangtersedia pada sumur “X”. Komparasi yang dilakukan memperlihatkan metode perhitunganpermeabilitas Hydraulic Flow Unit memiliki tingkat keakuratan yang lebih baik daripada metode Timurdan Tixier pada sumur “X