Towards Single-Ion Detection and Single-Photon Storage in Rare-Earth-Ion-Doped Crystals

Solid materials doped with rare-earth ions are considered an attractive platform for quantum information applications. One of the main reasons for this is the exceptionally long optical and hyperfine coherence times of the 4fn states, due to the shielding provided by the outer lying 5s and 5p electrons. This enables a large number of quantum operations before the system loses its coherence. Another reason is the wide inhomogeneous line broadening (∼ GHz), compared to the narrow homogeneous linewidth of individual ions (∼ kHz), which gives rise to a large number of spectrally separated ions that can, in principle, be individually addressed. In order to make use of this feature, a reliable detection (readout) of single ions is required. The excited states of 4f − 4f transitions have relatively long lifetimes ranging from hundreds of microseconds to milliseconds. This leads to a low spontaneous emission rate, which renders a direct detection of an individual ion challenging. Part of the research presented in this thesis addresses this issue by utilizing the Purcell effect to enhance the spontaneous emission rate of the ions. This can be achieved by placing nanocrystals doped with rare earth ions inside a microcavity. The density of states inside the cavity is modified compared to the density of states in free space, and as a consequence, the lifetime of the excited state of the ion becomes shorter. Y2O3 nanocrystals doped with Nd3+ ions were investigated, the Nd3+ ions being candidate for a readout ion that could potentially be used to probe the state of co-doped qubit ions in a non-destructive measurement. A fiber based microcavity was constructed for use at cryogenic temperatures. A side of fringe locking scheme was implemented to increase the stability of the cavity. Scanning cavity microscopy was demonstrated and used at room temperature to locate the nanocrystals, and cavity coupling to the 4f − 4f transitions of the Nd3+ ions was achieved. Cryogenic measurements were performed and cavity enhanced detection of an ensemble of a few ions was demonstrated.Another part of this research was focused on quantum memories. A quantum memory capable of storing a single photon and being able to retrieve it on demand with high fidelity are necessary for long distance quantum communication. The atomic frequency comb (AFC) scheme is an interesting quantum memory schemes that has been routinely demonstrated in rare-earth-ion-doped systems. To achieve on-demand storage, the standard AFC scheme is usually combined with bright optical pulses to transfer a stored photon into and out of the spin levels; referred to as the spin-wave storage scheme. However, these bright pulses create a high optical background, which makes it challenging to store and recall single photons. In this thesis, an extension of the standard AFC protocol that utilizes the linear Stark effect to perform noise-free, on-demand storage without the need for spin transfer pulses, is presented. The modified protocol was experimentally implemented in Pr3+:Y2SiO5 using weak coherent states as a memory input. A signal-to-noise ratio (SNR) of 570 was achieved using an average of 0.1 photons per pulse for storage, limited by the detector dark current. An order of magnitude higher SNR was estimated for storage of single-photon Fock states. This SNR, to the best of the author’s knowledge, is unsurpassed for the presented technique. A standard AFC analytical model was modified to incorporate the presented technique technique, and to investigate the storage performance of other materials for practical use in quantum networks. The Stark shift technique was also combined with the spin-wave storage scheme, providing another tool that could improve the performance of spin-wave storage at the single-photon level

Influence of Several Nano Minerals on The Mechanical Properties of Fresh and hardened Concrete

The current study aims at obtaining the influence of adding several nano-minerals on the mechanical properties of fresh and hardened concrete. Four types of Nano minerals were investigated in this work; namely: Brown Iron Oxide, Barium Sulfate, Titanium Dioxide and Poly Acrylic Acid. Five contents of each nano-minerals were studied. A range of contents starting from 0.5% to 2.5% with an increment of 0.5% by cement content of Brown Iron Oxide and Barium Sulfate was investigated. The Titanium Dioxide and Poly Acrylic Acid were added to concrete in percentages of 1% to 5% with an increment of 1% by cement content. Adding 5% Poly Acrylic Acid to the other three nano-minerals at selected contents separately was also studied. The measured mechanical properties of concrete comprised slump value, 7 and 28 days compressive strength. Some of the results revealed that there was 24% increase in the slump value corresponding to every 1% increase in PAA content. An improvement of 6.9% in the 28 days compressive strength was measured at every 0.5% increase of Brown Iron Oxide. It was also found that by adding 5% Poly Acrylic Acid and 2.5% Brown Iron Oxide to the concrete at the same time, the slump increased from 90 mm to 170 mm (88.9% increase) and the 28 days compressive strength improved from 37.37 kg/cm2 to 49.35 kg/cm2 (32.1% increase)

The level of Applying Total Quality Standards in Graduate Studies at Palestinian Universities, Gaza

الملخص: هدفت الدراسة إلى التعرف على مستوى تطبيق معايير الجودة الشاملة في الدراسات العليا في الجامعات الفلسطينية من وجهة نظر الطلبة، واستخدم الباحث المنهج الوصفي التحليلي لتحقيق أهداف الدراسة، وأعد استبانة مكونة من (33) فقرة موزعة على (3) مجالات تم توزيعها على عينة عشوائية قدرها (129) طالبا وطالبة شكلت (15%) من مجتمع الدراسة البالغ عددهم (860) وذلك لجمع بيانات الدراسة، وقد توصلت الدراسة إلى النتائج الآتية: أن الدرجة الكلية لمستوى تطبيق معايير الجودة الشاملة في الدراسات العليا من وجهة نظر الطلبة، كان بدرجة تقدير متوسطة، وبوزن نسبي (62.83%)، وقد حصل مجال عضو هيئة التدريس على المرتبة الأولى، وحصل مجال الإدارة الجامعية على المرتبة الأخيرة، ولا توجد فروق ذات دلالة إحصائية بين متوسطات تقدير أفراد عينة الدراسة لمستوى تطبيق معايير الجودة الشاملة في الدراسات العليا في الجامعات الفلسطينية تعزى لمتغيرات: الدراسة، والجنس، والجامعة، والمستوى الدراسي، وتوصي الدراسة بالعديد من التوصيات أهمها: أولاً: ضرورة مضاعفة الجهود لزيادة العمل وفق معايير الجودة الشاملة في الدراسات العليا بالجامعات الفلسطينية، وتنمية وتطوير الموارد البشرية باستمرار لتطوير أداء الدراسات العليا بالجامعات الفلسطينية. ثانياً: عادة النظر في صياغة الرؤى المستقبلية للجامعات الفلسطينية وفق معايير إدارة الجودة الشاملة بمشاركة واسعة من العاملين بالجامعات لضمان تحقيق العمل وفق معايير الجودة الشاملة. ثالثاً: الاهتمام بضبط المدخلات الجامعية لضمان مخرجات وفق معايير الجودة من خلال العمل الحثيث والمتواصل على تطبيق الجودة الشاملة في مرحلة العمليات. الكلمات المفتاحية: معايير الجودة الشاملة، الدراسات العليا، الجامعات الفلسطينية. The study aimed to identify the level of applying total quality standards in the graduate studies at the Palestinian universities from the students' perspective. The researcher used the descriptive analytical method to achieve the objectives. A questionnaire, consisting of (33) items divided into (3) themes, was developed and distributed to the sample of the study which was (129) male and female students, approximately constituting (15%) of the study population (860 members). To collect the data, the questionnaire was distributed to the sample, data was analyzed and the following results were obtained. The overall degree of applying the total quality standards in higher studies from the perspective of students was on average with a proportional weight of (62.83%). The theme related to the teaching staff scored the first rank while the theme related to the university administration scored the last rank. In addition, there were no statistically significant differences between the means of the study sample members regarding the degree of applying total quality standards in the graduate studies at the universities that were attributed to the variables of gender, university, and the academic level. Finally, the study proposed major recommendations the first of which was that more efforts should be exerted in order to improve the application of total quality standards in the postgraduate studies at Palestinian universities, and to continuously develop human resources as well. The second recommendation was that there should be a revision of future visions of Palestinian universities according to the total quality management standards, with wide participation of the university staff to ensure compliance with the total quality standards. The last major recommendation suggested by the study was to consider the university inputs to ensure that the outputs are in line with the quality standards. This can be achieved through persistent and continuous efforts on the application of total quality standards during the processing phase Keywords: Total quality standards, Graduate, Palestinian universities

Design Optimization of Semi-Rigidly Connected Steel Frames Using Harmony Search Algorithm

In this paper, a design optimization algorithm is presented for non-linear steel frames with semi-rigid beamcolumnconnections using harmony search algorithm. The design algorithm obtains the minimum steel weight by selecting from a standard set of steel sections. Strength constraints of American Institute of Steel Construction - Load and Resistance Factor Design (AISC-LRFD) specification, displacement, deflection, size constraint and lateral torsional bulking are imposed on frames. Harmony search (HS) is a recently developed meta-heuristic search algorithm which is based on the analogy between the natural musical performance and searching the solutions to optimization problems. The HS algorithm accounts for the effect of connections’ flexibility and the geometric non-linearity of the members. The Frye–Morris polynomial model is used for modeling semi-rigid connections. Two design examples with extended end plate without column stiffeners are presented to demonstrate the application and validity of the algorithm

Investigating the Effect of Sulfate Attack on Compressive Strength of Recycled Aggregate Concrete

This research aimed at studying the effect of sulfate attack on the compressive concrete strength with various percentages of recycled aggregate replacements (0%, 30%, 60% and 100%). Water cement ratio (0.42) are used, MgSO4 solution was used with two concentration (6% and 9 %) to represent the effect of sulfate attack on the concrete compressive strength. The experimental tests focused on physical properties of recycled aggregate; density, unit weight, sieve analysis, Los Angles test and specific gravity. Tests have also been performed on 108 concrete cubes samples at 7 days, 14 days and 28 days for compressive strength. The results of  compressive strength at 28 days using (0%, 30%, 60% and 100%) recycled aggregate are (330, 280, 266 and 244) Kg/cm2 respectively, with reduction in compressive strength was (15.2%, 19.4% and 26%)  for replacement ratio (30%, 60% and 100%) respectively. MgSO4 solution has an effect on compressive strength after 90 days of immersion in 6% and 9% concentrated of MgSO4 solution. The results of this study show that the reduction in compressive strength using recycled aggregate is more sensitive against the sulfate attack compared with natural aggregate

Assessment on engineering properties and CO2 emissions of recycled aggregate concrete incorporating waste products as supplements to Portland cement

This paper presents an experimental investigation on the durability properties and carbon dioxide (CO2) emissions of concrete developed using waste products. The concrete comprised of recycled concrete aggregate (RA) as a complete coarse aggregate replacement. In addition, rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) were used as replacement materials for cement at levels up to 30%. The supplementary cementitious materials (SCMs) were used in RA concrete with the aim of reducing the dependency on cement as a stand-alone binder. The compressive strength, water absorption, chloride-ion penetration and electrical resistivity were investigated for RA concrete containing SCMs. Moreover, the residual compressive strength was also examined along with the weight loss to check the elevated temperature resistance of RA concrete with SCMs. The results revealed that

Effect of aggressive chemicals on durability and microstructure properties of concrete containing crushed new concrete aggregate and non-traditional supplementary cementitious …

The increasing awareness and usage of traditional supplementary cementitious materials (SCMs) in concrete have pressured the construction industry to look for alternatives to overcome the concerns over their plentiful availability in the future. This research illustrates the performance of recycled aggregate concrete prepared with the incorporation of available industrial by-products, namely rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) as alternatives for traditional SCMs. The effect of hydrochloric (HCl) acid and magnesium sulfate (MgSO 4) attack was evaluated by measuring the change in mass, compressive strength and microstructural analysis. The results revealed that the incorporation of RHA, POFA and POCP up to 30% minimizes concrete deterioration and loss in compressive strength when the specimens were exposed to HCl solution. In addition, the scanning electron