Nonadiabatic charge pumping across two superconductors connected through a normal metal region by periodically driven potentials

Periodically driven systems exhibit resonance when the difference between an excited state energy and the ground state energy is an integer multiple of $\hbar$ times the driving frequency. On the other hand, when a superconducting phase difference is maintained between two superconductors, subgap states appear which carry a Josephson current. A driven Josephson junction therefore opens up an interesting avenue where the excitations due to applied driving affect the current flowing from one superconductor to the other. Motivated by this, we study charge transport in a superconductor-normal metal-superconductor (SNS) junction where oscillating potentials are applied to the normal metal region. We find that for small amplitudes of the oscillating potential, driving at one site reverses the direction of current at the superconducting phase differences when difference between the subgap eigenenergies of the undriven Hamiltonian is integer multiple of $\hbar$ times the driving frequency. For larger amplitudes of oscillating potential, driving at one site exhibits richer features. We show that even when the two superconductors are maintained at same superconducting phase, a current can be driven by applying oscillating potentials to two sites in the normal metal differing by a phase. We find that when there is a nonzero Josephson current in the undriven system, the local peaks and valleys in current of the system driven with an amplitude of oscillating potential smaller than the superconducting gap indicates sharp excitations in the system. In the adiabatic limit, we find that charge transferred in one time period diverges as a powerlaw with pumping frequency when a Josephson current flows in the undriven system. Our calculations are exact and can be applied to finite systems. We discuss possible experimental setups where our predictions can be tested.Comment: 9 pages, 9 figures. Published versio

On the WW-algebra in the Calegero-Sutherland model using the Exchange operators

We study the $W_\infty$ algebra in the Calegero-Sutherland model using the exchange operators. The presence of all the sub-algebras of $W_\infty$ is shown in this model. A simplified proof for this algebra, in the symmetric ordered basics, is given. It is pointed out that the algebra contains in general, nonlinear terms. Possible connection to the nonlinear $W_\infty$ is discussed.Comment: Plain Tex, no figures, 13 page

Consistent Non-Minimal Couplings of Massive Higher-Spin Particles

The mutual compatibility of the dynamical equations and constraints describing a massive particle of arbitrary spin, though essential for consistency, is generically lost in the presence of interactions. The conventional Lagrangian approach avoids this difficulty, but fails to ensure light-cone propagation and becomes very cumbersome. In this paper, we take an alternative route--the involutive form of the equations and constraints--to guarantee their algebraic consistency. This approach enormously simplifies the search for consistent interactions, now seen as deformations of the involutive system, by keeping manifest the causal propagation of the correct number of degrees of freedom. We consider massive particles of arbitrary integer spin in electromagnetic and gravitational backgrounds to find their possible non-minimal local couplings. Apart from easily reproducing some well-known results, we find restrictions on the backgrounds for consistent propagation of such a particle in isolation. The results can be altered by non-local interactions that may arise from additional massive states in the interacting theory.Comment: 26 pages; to appear in Nuclear Physics B; analyses of consistent backgrounds improve

Hamiltonian vs Lagrangian Embedding of a Massive Spin-one Theory Involving 2-form Field

We consider the Hamiltonian and Lagrangian embedding of a first-order, massive spin-one, gauge non-invariant theory involving anti-symmetric tensor field. We apply the BFV-BRST generalised canonical approach to convert the model to a first class system and construct nil-potent BFV-BRST charge and an unitarising Hamiltonian. The canonical analysis of the St\"uckelberg formulation of this model is presented. We bring out the contrasting feature in the constraint structure, specifically with respect to the reducibility aspect, of the Hamiltonian and the Lagrangian embedded model. We show that to obtain manifestly covariant St\"uckelberg Lagrangian from the BFV embedded Hamiltonian, phase space has to be further enlarged and show how the reducible gauge structure emerges in the embedded model.Comment: Revtex, 13 pages, no figure, to appear in Int. J. Mod. Phys.

Women empowerment and micro finance : Case study from Kerala

The subject of micro-finance is considered as significant and emerging trend in the present scenario for the empowerment of women. Micro finance programmes are promoted as an important strategy for women’s empowerment. Micro finance builds mutual trust and confidence between bankers and rural poor to encourage banking in a segment of population where formal financial institutions usually find difficult to reach. The present paper examines the economic impact of micro finance beneficiaries and whether the economic empowerment has resulted in the generation of a set of self reliant women. The Thiruvananthapuram district of Kerala State was selected for the case study. The survey shows about the positive impact of the development programme of Kudumbashree, a micro financial institution in Kerala, India.women empowerment micro finance poverty.

The Hydrodynamical Limit of Quantum Hall system

We study the current algebra of FQHE systems in the hydrodynamical limit of small amplitude, long-wavelength fluctuations. We show that the algebra simplifies considerably in this limit. The hamiltonian is expressed in a current-current form and the operators creating inter-Landau level and lowest Landau level collective excitations are identified.Comment: Revtex, 16 page

India’s Revenue Deficit: A Challenge Ahead

A developing country like India needs revenue surplus for the capital investment at the same time to pursue the economic development through demand expansion it needs expenditure especially in the social sectors such as health, education etc,. The recent global economic crisis also compels India to induce the expenditure for sustainability of the growth that it has achieved recently. This also needs enormous expenditure. On the other hand, current expenditure over current revenue of an economy makes revenue deficit. India’s Thirteenth Finance Commission’s one of the recommendation is that revenue deficit (as % of GDP) of the Centre needs to be progressively reduced and eliminated, followed by emergence of a revenue surplus by 2014-15 and a long term and permanent target for the Central Government should be to maintain, at the minimum, a zero revenue deficit. In the light of the above recommendation analyzing revenue deficit is imperative at this hour.India; Revenue Deficit; Revenue Receipts; Revenue Expenditure; Thirteenth Finance Commission