A 3D topological insulator quantum dot for optically controlled quantum memory and quantum computing

We present the model of a quantum dot (QD) consisting of a spherical core-bulk heterostructure made of 3D topological insulator (TI) materials, such as PbTe/Pb$_{0.31}$Sn$_{0.69}$Te, with bound massless and helical Weyl states existing at the interface and being confined in all three dimensions. The number of bound states can be controlled by tuning the size of the QD and the magnitude of the core and bulk energy gaps, which determine the confining potential. We demonstrate that such bound Weyl states can be realized for QD sizes of few nanometers. We identify the spin locking and the Kramers pairs, both hallmarks of 3D TIs. In contrast to topologically trivial semiconductor QDs, the confined massless Weyl states in 3D TI QDs are localized at the interface of the QD and exhibit a mirror symmetry in the energy spectrum. We find strict optical selection rules satisfied by both interband and intraband transitions that depend on the polarization of electron-hole pairs and therefore give rise to the Faraday effect due to Pauli exclusion principle. We show that the semi-classical Faraday effect can be used to read out spin quantum memory. When a 3D TI QD is embedded inside a cavity, the single-photon Faraday rotation provides the possibility to implement optically mediated quantum teleportation and quantum information processing with 3D TI QDs, where the qubit is defined by either an electron-hole pair, a single electron spin, or a single hole spin in a 3D TI QD. Remarkably, the combination of inter- and intraband transition gives rise to a large dipole moment of up to 450 Debye. Therefore, the strong-coupling regime can be reached for a cavity quality factor of $Q\approx10^{4}$ in the infrared wavelength regime of around $10\:\mu$m.Comment: 19 pages, 11 figures, RevTe

Information, Candidate Selection, and the Quality of Representation: Evidence from Nepal

How do we improve the quality of representation in new democracies? This paper studies candidate selection by party leaders and asks whether poor information about public preferences can lead elite choices to diverge from mass opinion. Working with a political party in Nepal, we show that while elites value voter preferences, these preferences only explain one third of elite candidate selection. Next, we embed an experiment in actual candidate selection deliberations for this party and find that party leaders not only select different candidates when polling data are presented to them, but that their updated decisions also improve the party’s vote share. By opening the black-box of candidate selection, this paper demonstrates that closing the information gap between elites and voters has the power to improve the quality of representation

PART TIME FARMING, FARM PRODUCTIVITY, AND FARM INCOME: EVIDENCE FROM THE SOUTHEAST US

We analyzed the effect of part time farming in the US using a panel data analysis method. Data from three census years on ten southern states and the counties therein indicated that part time farming has a positive impact on the total value of the farm products produced. Although the result is preliminary, it sheds an important light on the changing farm structure in the USA.Agricultural Finance,

MPI-Vector-IO: Parallel I/O and Partitioning for Geospatial Vector Data

In recent times, geospatial datasets are growing in terms of size, complexity and heterogeneity. High performance systems are needed to analyze such data to produce actionable insights in an efficient manner. For polygonal a.k.a vector datasets, operations such as I/O, data partitioning, communication, and load balancing becomes challenging in a cluster environment. In this work, we present MPI-Vector-IO 1 , a parallel I/O library that we have designed using MPI-IO specifically for partitioning and reading irregular vector data formats such as Well Known Text. It makes MPI aware of spatial data, spatial primitives and provides support for spatial data types embedded within collective computation and communication using MPI message-passing library. These abstractions along with parallel I/O support are useful for parallel Geographic Information System (GIS) application development on HPC platforms

PRODUCTION TERMINATION AS AN ALTERNATIVE TO MITIGATE NUTRIENT POLLUTION

Nutrient runoff from agricultural land can be reduced through production termination to mitigate water pollution. The willingness to accept value to terminate the broiler production is evaluated using sample selection model. The result showed a positive relationship between the decision to participation and stated WTA value indicating the producers are willing to terminate the production but at high cost. The farmer’s perception about government role on water pollution, farm income, information and awareness about other pollution reduction alternatives play a major role on stated WTA amount as well as on participation decision.Environmental Economics and Policy,