Interference-induced splitting of resonances in spontaneous emission

We study the resonance fluorescence from a coherently driven four-level atom in the Y-type configuration. The effects of quantum interference induced by spontaneous emission on the fluorescence properties of the atom are investigated. It is found that the quantum interference resulting from cascade emission decays of the atom leads to a splitting of resonances in the excited level populations calculated as a function of light detuning. For some parameters, interference assisted enhancement of inner sidebands and narrowing of central peaks may also occur in the fluorescence spectrum. We present a physical understandingof our numerical results using the dressed state description of the atom-light interaction.Comment: 7 pages including 7 figure

Growth pattern of Prinsepia. utilis (Bhenkal) at different girth classes growing naturally at inner Himalayan region

Present study was undertaken to evaluate the growth pattern of Prinsepia.utilis growing at Western Himalayan region at four study sites i.e. S1 (Jhala), S2 (Dharali), S3 (Jaspur) and S4 (Sukki) at Uttarkashi district at Garhwal Himalaya in the year 2008-09 The data recorded for different parameters related to growth of Prinsepia.utilis at different sites showed variation. Growth parameters viz. lengths of plants, branch number, length of seed, seed output etc. were examined during the present study. Maximum shoot length at 25.1-30 cm girth class (220.5±23.13 cm), maximum leaf area at girth class 5.1 – 10 cm (1.98) and the maximum fruit productivity at girth class 25.1 – 30 cm (1800.63g) were observed where as minimum production was recorded at girth class 10.1 – 15 cm (756.9g)

Modeling and Performance prediction of Eureka-147 OFDM based DAB system

The new digital radio system DAB (Digital Audio Broadcasting), developed within the Eureka 147 project is a very innovative and universal multimedia broadcast system that has the potential to replace existing AM and FM audio broadcast services in many parts of the world in the near future. DAB employs coded OFDM technology that enables it for mobile reception and makes receivers highly robust against channel multipath fading effect. In this paper, we have analyzed the bit error rate (BER) performance of DAB system conforming to the parameters established by the ETSI (EN 300 401) using frequency interleaving and Forward Error Correction (FEC) in different transmission channels. The results shows DAB to be suitable radio broadcasting technology for high performance in mobile environment

Tunneling and traversal of ultracold atoms through vacuum-induced potentials

We examine the passage of ultracold two-level atoms through the potential produced by the vacuum of the cavity field. We find that the phase time may be considered as the appropriate measure of the time required for the atom to traverse the cavity. The phase tunneling time for ultracold atoms exhibits both super- and sub-classical time and we show how this behavior may be understood in terms of the momentum dependence of the phase of transmission amplitude. The passage of the atom through the cavity is unique, as it involves a coherent addition of the transition amplitudes corresponding to both barrier and well

How CIOs Can Enable Governance of Value Nets

Value nets are the architecture of sourcing agreements and alliances that firms implement to gain complementary resources and capabilities from other firms. They are a source of innovation, growth, and competitive success. However, governing value nets is challenging, and the IT support needed to enable them depends on the governance mode a firm chooses. Based on case studies of three Fortune 100 firms, we define three governance modes—prescriptive, evaluative, and collaborative. Prescriptive governance specifies partners\u27 activities and retains decisions rights. It is effectively supported by dashboards that monitor the status of partners\u27 activities, alerts that surface exceptions and errors, business rules that automate activities and handling of errors, and extended enterprise architectures that protect intellectual property. Evaluative governance delegates decision rights to partners for operational execution and assesses their capabilities through periodic evaluations. It is effectively supported by loosely coupled processes that provide partners with limited autonomy, periodic reporting of performance on service level agreements, and data and process mining directed at improving partners\u27 capabilities. Collaborative governance promotes peer-to-peer collaboration with value net partners. It is supported by metadata architectures that control repositories of information and process resources, by consistent business rules to coordinate processes, by monitoring of the total costs of the relationship, and by business intelligence for predictive monitoring. CIOs and senior IT executives can apply these findings to choose an appropriate governance mode and enable it with appropriate IT applications and processes

Digital Audio Broadcast: Modulation, Transmission & Performance Analysis

Radio broadcasting technology has evolved rapidly over the last few years due to ever increasing demands for as high quality sound services with ancillary data transmission in mobile environment. In order to accomplish this, Members of European Broadcasting Union (EBU), the European Telecommunications Standards Institute (ETSI) and International Telecommunications Union (ITU-R) developed a completely new digital radio broadcasting technology called the Eureka- 147 Digital Audio Broadcasting (DAB) system which improves the overall broadcasting performance by delivering near CD quality audio and data services in mobile receivers along with efficient use of the available radio frequency spectrum. Digital Audio Broadcasting (DAB) system developed within the Eureka 147 Project is a new digital radio technology for broadcasting radio stations that provides high-quality audio and data services to both fixed and mobile receivers. The system uses COFDM technology that combats the effect of multipath fading & ISI and makes it spectrally more efficient compared with existing AM/FM systems. This project presents the performance analysis of Eureka-147 DAB system. DAB transmission mode-II is implemented first and then extended successfully to other modes. A frame-based processing is used in this study. Performance studies for AWGN, Rayleigh and Rician channels have been conducted. For all studies BER has been used as performance criteria. This project also discusses issues related to system performance using concatenated coding technique, including the outer Block code, the inner convolutional code, outer BCH code and the inner convolutional code

K2_2CoS2_2: A new two-dimensional in-plane antiferromagnetic insulator

The recent discovery of two-dimensional (2D) magnetic materials has brought magnetism to the flatland. This has opened up exciting opportunities for the exploration of fundamental physics as well as for novel device applications. Here, we predict a new thermodynamically stable 2D magnetic material, K$_2$CoS$_2$, which retains its in-plane anti-ferromagnetic order down to the monolayer and bilayer limits. We find that the magnetic moments ($2.5 \mu_B/$Co) are aligned along the intra-Co chains, from monolayer to bulk. The non-magnetic electronic spectrum of both the monolayer and bilayer films is found to host flat bands and van-Hove singularities, which in instrumental in giving rise to the the magnetic ground state. Based on classical Monte-Carlo simulations, we estimate the Neel temperature for the antiferromagnetic monolayer to be $\approx 15$K. Our study thus establishes that K$_2$CoS$_2$ hosts a robust antiferromagnetic state which persists from the monolayer limit to the bulk material.Comment: final revised version; Phys. Rev. B 102, 035420 (2020