27,410 research outputs found

    Computing with spins: From classical to quantum computing

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    This article traces a brief history of the use of single electron spins to compute. In classical computing schemes, a binary bit is represented by the spin polarization of a single electron confined in a quantum dot. If a weak magnetic field is present, the spin orientation becomes a binary variable which can encode logic 0 and logic 1. Coherent superposition of these two polarizations represent a qubit. By engineering the exchange interaction between closely spaced spins in neighboring quantum dots, it is possible to implement either classical or quantum logic gates.Comment: 3 figure

    Local government finance: challenges in revenue-raising at the Municipal Corporation of Delhi

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    The main objective of this paper is to examine the extent to which the capital city of Delhi has gained financial autonomy over the years. In order to better understand its progress, the paper compares the periods before and after the submission of the Third State Finance Commission Report of Delhi. The main findings suggest there have been some efforts to reduce reliance on transfers from upper tiers of government and to strengthen ‘own revenues’ atthe Municipal Corporation of Delhi (MCD). A greater diversification of tax and non-tax revenue sources is responsible for this improvement. In the second period, other tax sources such as corporation tax and electricity tax gained in importance.  Non-tax revenues were also strengthened by higher collection of certain components such as conversion charges. However, own revenues have been inadequate to meet growing expenditure requirements, resulting in high revenue expenditure gaps. Further, the growth in Gross State Domestic Product (GSDP has not led to a rise in own revenues for MCD.Rather, the paper finds that higher GSDP and its tertiary sector components are associated with higher expenditures in MCD. As far as local revenues are concerned, higher GSDP is associated with higher transfers, but has no discernible impact on own revenues.

    Charged Higgs bosons in the extended supersymmetric scenario at the LHC

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    We investigate an extension of the Minimal Supersymmetric Standard Model (MSSM) containing a SU(2)SU(2) Higgs triplet of zero hypercharge and a gauge singlet. We focus on a scenario of this model which allows a light pseudoscalar and/or a scalar below 100100 GeV in the spectrum, consistent with the most recent data from the LHC and the earlier data from the LEP experiments. The triplet extension gives rise to two additional charged Higgs bosons which do not couple to fermions but can decay into ZW±Z W^\pm. The presence of a very light pseudoscalar opens a1W±a_1 W^\pm decay mode for the light charged Higgs boson just like Z3Z_3 symmetric singlet-extension (NMSSM). A triplet type charged Higgs can be produced via vector boson fusion at the tree-level which is absent in 2HDM and MSSM and NMSSM. If such charged Higgs boson is pair produced both ZW±Z W^\pm and a1W±a_1 W^\pm decay modes can be probed which can prove the existence of triplet and singlet both.Comment: 10 pages, 7 figures, contribution to LHCP 2016 conference proceeding

    Optimal Concentration for SU(1,1) Coherent State Transforms and an analogue of the Lieb-Wehrl Conjecture for SU(1,1)

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    We derive a lower bound for the Wehrl entropy in the setting of SU(1,1). For asymptotically high values of the quantum number k, this bound coincides with the analogue of the Lieb-Wehrl conjecture for SU(1,1) coherent states. The bound on the entropy is proved via a sharp norm bound. The norm bound is deduced by using an interesting identity for Fisher information of SU(1,1) coherent state transforms and a new family of sharp Sobolev inequalities on the hyperbolic plane. To prove the sharpness of our Sobolev inequality, we need to first prove a uniqueness theorem for solutions of a semi-linear Poisson equation (which is actually the Euler-Lagrange equation for the variational problem associated with our sharp Sobolev inequality) on the hyperbolic plane. Uniqueness theorems proved for similar semi-linear equations in the past do not apply here and the new features of our proof are of independent interest, as are some of the consequences we derive from the new family of Sobolev inequalities.Comment: 24 pages, 1 figur
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