Phonon sidebands of color centers in hexagonal boron nitride

Low temperature photoluminescence spectra of a color center in hexagonal boron nitride are analyzed. The acoustic phonon sideband can be described by a deformation coupling proportional to strain to a phonon bath that is effectively two dimensional. The optical phonon band is described by Frohlich coupling to the LO-branches, and a deformation coupling proportional to lattice displacement for the TO-branch. The resonances expressed in the optical band vary from defect to defect, in some emitters, coupling to out-of-plane polarized phonons is reported.Comment: 7 pages, 4 fig

Photophysical Properties of Single Photon Emitters in Hexagonal Boron Nitride

The development of photonic based quantum technologies such as quantum encryption and quantum computing is mainly restrained by the quality of single photon emitter. Effects like phonon interaction, emission purity, stability and decoherence are the major issues. So far quantum dots are leading the race in terms of indistinguishability, emission purity and stability but low collection efficiency and operation at cryogenic/low temperature are major roadblocks. Hexagonal-Boron Nitride (hBN) is a 2D material with stable single photon emission even at 800 °C. hBN is an emerging material, attracting interest from a wider research community but information about the identity of the emitting defects is very limited. The aim of this work is to use the experimental techniques to probe the emitter and comment on the possible origins of the emission.Engineering and Physical Sciences Research Council (EPSRC)Engineering and Physical Sciences Research Council (EPSRC

Practical figures of merit and thresholds for entanglement distribution in quantum networks

Before global-scale quantum networks become operational, it is important to consider how to evaluate their performance so that they can be built to achieve the desired performance. We propose two practical figures of merit for the performance of a quantum network: the average connection time and the average largest entanglement cluster size. These quantities are based on the generation of elementary links in a quantum network, which is a crucial initial requirement that must be met before any long-range entanglement distribution can be achieved and is inherently probabilistic with current implementations. We obtain bounds on these figures of merit for a particular class of quantum repeater protocols consisting of repeat-until-success elementary link generation followed by joining measurements at intermediate nodes that extend the entanglement range. Our results lead to requirements on quantum memory coherence times, requirements on repeater chain lengths in order to surpass the repeaterless rate limit, and requirements on other aspects of quantum network implementations. These requirements are based solely on the inherently probabilistic nature of elementary link generation in quantum networks, and they apply to networks with arbitrary topology.Comment: 17 pages, 7 figures. v2: extensively revised and rewritten. Title and abstract modified; added a section on overcoming the repeaterless rate limit; modified statement of Theorem 1. v3: minor changes to match the published versio

Smart Asset Management for Electric Utilities: Big Data and Future

This paper discusses about future challenges in terms of big data and new technologies. Utilities have been collecting data in large amounts but they are hardly utilized because they are huge in amount and also there is uncertainty associated with it. Condition monitoring of assets collects large amounts of data during daily operations. The question arises "How to extract information from large chunk of data?" The concept of "rich data and poor information" is being challenged by big data analytics with advent of machine learning techniques. Along with technological advancements like Internet of Things (IoT), big data analytics will play an important role for electric utilities. In this paper, challenges are answered by pathways and guidelines to make the current asset management practices smarter for the future.Comment: 13 pages, 3 figures, Proceedings of 12th World Congress on Engineering Asset Management (WCEAM) 201

Morphea (Localized Scleroderma) Presenting With Recurrent Skin and Soft Tissue Infections: A Diagnostic Dilemma.

Morphea or localized scleroderma is reported to be triggered through diverse stimuli. We present a case of morphea that presented as a non-healing wound with superimposed methicillin-sensitive Staphylococcus aureus (MSSA) infection. In our case, morphea was thought to have been potentially triggered by a post-surgical infection. We discuss the potential infectious triggers and common infections that may confound the diagnosis