Entanglement and Coherence in Classical and Quantum Optics

We explore the concepts of coherence and entanglement as they apply to both the classical and quantum natures of light. In the classical domain, we take inspiration from the tools and concepts developed in foundational quantum mechanics and quantum information science to gain a better understanding of classical coherence theory of light with multiple degrees of freedom (DoFs). First, we use polarization and spatial parity DoFs to demonstrate the notion of classical entanglement, and show that Bell\u27s measure can serve as a useful tool in distinguishing between classical optical coherence theory. Second, we establish a methodical yet versatile approach called \u27optical coherency matrix tomography\u27 for reconstructing the coherency matrix of an electromagnetic beam with multiple DoFs. This technique exploits the analogy between this problem in classical optics and that of tomographically reconstructing the density matrix associated with multipartite quantum states in quantum information science. Third, we report the first experimental measurements of the 4 x 4 coherency matrix associated with an electromagnetic beam in which polarization and a spatial DoF are relevant, ranging from the traditional two-point Young\u27s double slit to spatial parity and orbital angular momentum modes. In the quantum domain, we use the modal structure of classical fields to develop qubits and structure Hilbert spaces for use in quantum information processing. Advancing to three-qubit logic gates is an important step towards the success of optical schemes for quantum computing. We experimentally implement a variety of two- and three- qubit, linear and deterministic, single-photon, controlled, quantum logic gates using polarization and spatial parity qubits. Lastly, we demonstrate the implementation of two-qubit single-photon logic using polarization and orbital angular momentum qubits

China's energy policy as a pillar of its peaceful development : strategies, challenges and implications of the Chinese energy engagement in the oil and hydro power sectors in Africa

published_or_final_versionInternational and Public AffairsMasterMaster of International and Public Affair

Data Analysis using Hierarchical Computing

Supervised learning algorithm can be used to mine datasets on the internet. Stock market, Medical organizations, education institutes all store a huge amount of data .For the purpose of analyzing this data classification algorithms can be used. The processing of these algorithms can be done using eithera single machine either sequentially or parallel or on multiple machine either using 1)Parallel approach 2)Cloud approach 3)Hierarchical approach

Single-photon three-qubit quantum logic using spatial light modulators

The information-carrying capacity of a single photon can be vastly expanded by exploiting its multiple degrees of freedom: spatial, temporal, and polarization. Although multiple qubits can be encoded per photon, to date only two-qubit single-photon quantum operations have been realized. Here, we report an experimental demonstration of three-qubit single-photon, linear, deterministic quantum gates that exploit photon polarization and the two-dimensional spatial-parity-symmetry of the transverse single-photon field. These gates are implemented using a polarization-sensitive spatial light modulator that provides a robust, non-interferometric, versatile platform for implementing controlled unitary gates. Polarization here represents the control qubit for either separable or entangling unitary operations on the two spatial-parity target qubits. Such gates help generate maximally entangled three-qubit Greenberger–Horne–Zeilinger and W states, which is confirmed by tomographical reconstruction of single-photon density matrices. This strategy provides access to a wide range of three-qubit states and operations for use in few-qubit quantum information processing protocols

Rapid systematic review of neonatal COVID-19 including a case of presumed vertical transmission

Objective: To carry out a systematic review of the available studies on COVID-19 (coronavirus disease 2019) in neonates seen globally since the onset of the COVID-19 global pandemic in 2020. The paper also describes a premature baby with reverse transcription (RT)-PCR-positive COVID-19 seen at the Blackpool Teaching Hospitals NHS Foundation Trust, UK. Design: We conducted a multifaceted search of the Cumulative Index to Nursing and Allied Health Literature, Embase, Medline and PubMed from 1 December 2019 to 12 May 2020 to harvest articles from medical journals and publications reporting cases of COVID-19 in neonates from anywhere in the world. Additional searches were also done so as not to miss any important publications. Write-up was in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, the protocol for the review was registered with International Prospective Register of Systematic Reviews (PROSPERO), and risk of bias was analysed with the Newcastle-Ottawa tool. Additionally, the preterm neonate with COVID-19 from our hospital is also reported. Results: The systematic review has revealed eight studies where neonates have been described to have confirmed COVID-19, with low risk of bias. Of the 10 reported cases elsewhere, only three are likely to be vertically transmitted, while seven occurred in the postperinatal period and are likely to have been postnatally acquired. All neonates had a mild course, recovered fully and were negative on retesting. Our case of COVID-19 in a 32-week premature baby from the UK was delivered by emergency caesarean section, with the mother wearing a face mask and the family having no contact with the neonate, suggesting vertical transmission. On day 33, the neonate was asymptomatic but was still RT-PCR-positive on nasopharyngeal airway swab. Conclusions: Neonatal infection is uncommon, with only two previously reported cases likely to be of vertical transmission. The case we report is still RT-PCR-positive on day 28 and is asymptomatic. Ongoing research is needed to ascertain the epidemiology of COVID-19 in neonates

Analysis of nucleosome repositioning by yeast ISWI and Chd1 chromatin remodeling complexes

ISWI proteins form the catalytic core of a subset of ATP-dependent chromatin remodelling activities in eukaryotes from yeast to man. Many of these complexes have been found to reposition nucleosomes, but with different directionalities. We find that the yeast Isw1a, Isw2 and Chd1 enzymes preferentially move nucleosomes towards more central locations on short DNA fragments whereas Isw1b does not. Importantly, the inherent positioning properties of the DNA play an important role in determining where nucleosomes are relocated to by all of these enzymes. However, a key difference is that the Isw1a, Isw2 and Chd1 enzymes are unable to move nucleosomes to positions closer than 15 bp from a DNA end whereas Isw1b can. We also find that there is a correlation between the inability of enzymes to move nucleosomes close to DNA ends and the preferential binding to nucleosomes bearing linker DNA. These observations suggest that the accessibility of linker DNA together with the positioning properties of the underlying DNA play important roles in determining the outcome of remodelling by these enzymes

Effect of hyperfine structure on atomic frequency combs in Pr:YSO

Quantum memory will be a key component in future quantum networks, and atomic frequency combs (AFCs) in rare-earth-doped crystals are one promising platform for realizing this technology. We theoretically and experimentally investigate the formation of AFCs in Pr3+:Y2SiO5, with an overall bandwidth of 120 MHz and tooth spacing ranging from 0.1 MHz to 20 MHz, showing agreement between our calculations and measurements. We observe that the echo efficiency depends crucially on the AFC tooth spacing. Our results suggest approaches to developing a high-efficiency AFC quantum memory.Comment: 20 pages, 7 figure

Snf2 family ATPases and DExx box helicases:differences and unifying concepts from high-resolution crystal structures

Proteins with sequence similarity to the yeast Snf2 protein form a large family of ATPases that act to alter the structure of a diverse range of DNA–protein structures including chromatin. Snf2 family enzymes are related in sequence to DExx box helicases, yet they do not possess helicase activity. Recent biochemical and structural studies suggest that the mechanism by which these enzymes act involves ATP-dependent translocation on DNA. Crystal structures suggest that these enzymes travel along the minor groove, a process that can generate the torque or energy in remodelling processes. We review the recent structural and biochemical findings which suggest a common mechanistic basis underlies the action of many of both Snf2 family and DExx box helicases