Arun Kumar
Articles written in Pramana – Journal of Physics
Volume 42 Issue 6 June 1994 pp 455-465
On phases and length of curves in a cyclic quantum evolution
The concept of a curve traced by a state vector in the Hilbert space is introduced into the general context of quantum evolutions and its length defined. Three important curves are identified and their relation to the dynamical phase, the geometric phase and the total phase are studied. These phases are reformulated in terms of the dynamical curve, the geometric curve and the natural curve. For any arbitrary cyclic evolution of a quantum system, it is shown that the dynamical phase, the geometric phase and their sums and/or differences can be expressed as the integral of the contracted length of some suitably-defined curves. With this, the phases of the quantum mechanical wave function attain new meaning. Also, new inequalities concerning the phases are presented.
Volume 56 Issue 2-3 February 2001 pp 393-401 Quantum Information Processing
Interference due to coherence swapping
Arun Kumar Pati Marek Zukowski
We propose a method called ‘coherence swapping’ which enables us to create superposition of a particle in two distinct paths, which is fed with initially incoherent, independent radiation. This phenomenon is also present for the charged particles, and can be used to swap the effect of flux line due to the Aharonov-Bohm effect. We propose an optical version of experimental set-up to test the coherence swapping. The phenomenon, which is simpler than entanglement swapping or teleportation, raises some fundamental questions about the true nature of wave-particle duality, and also opens up the possibility of studying the quantum erasure from a new angle.
Volume 59 Issue 2 August 2002 pp 221-228
Quantum cobwebs: Universal entangling of quantum states
Entangling an unknown qubit with one type of reference state is generally impossible. However, entangling an unknown qubit with two types of reference states is possible. To achieve this, we introduce a new class of states called
Volume 75 Issue 6 December 2010 pp 1267-1272 Conributed Papers
Laser pulse heating of nuclear fuels for simulation of reactor power transients
C S Viswanadham K C Sahoo T R G Kutty K B Khan V P Jathar S Anantharaman Arun Kumar G K Dey
It is important to study the behaviour of nuclear fuels under transient heating conditions from the point of view of nuclear safety. To simulate the transient heating conditions occurring in the known reactor accidents like loss of coolant accident (LOCA) and reactivity initiated accident (RIA), a laser pulse heating system is under development at BARC, Mumbai. As a prelude to work on irradiated nuclear fuel specimens, pilot studies on unirradiated UO2 fuel specimens were carried out. A laser pulse was used to heat specimens of UO2 held inside a chamber with an optically transparent glass window. Later, these specimens were analysed by metallography and X-ray diffraction. This paper describes the results of these studies.
Volume 79 Issue 4 October 2012 pp 821-824 Poster Presentations
Arun Kumar for the CMS Collaboration
A search for the Standard Model boson decaying to two 𝑍 bosons with a subsequent decay to a final state with two leptons and two quark jets, $H \rightarrow ZZ \rightarrow l^{+}l^{-} q\bar{q}$, is presented. Data corresponding to an ntegrated luminosity of 1.6 fb-1 of LHC proton-proton collisions at the centre-of-mass energy of 7 TeV were collected and analysed by the CMS experiment. The selection to discriminate between signal and background events is based on kinematic and topological quantities, which include the angular spin correlations of the decay products. The events are classified according to the probability of the jets to originate from quarks of light or heavy flavour or from gluons. No evidence for a Higgs boson is found and upper limits on the Higgs boson production cross-section are set in the range of masses between 226 and 600 GeV/c2.
Volume 82 Issue 2 February 2014 pp 237-242 Contributed Papers
Laser-assisted surface cleaning of metallic components
Aniruddha Kumar R B Bhatt P G Behere Mohd Afzal Arun Kumar J P Nilaya D J Biswas
Removal of a thin oxide layer from a tungsten ribbon and ThO2 particulates from zircaloy surface was achieved using a pulsed Nd:YAG laser. The removal mechanism of the oxide layer from the tungsten ribbon was identified as spallation or sublimation depending on the wavelength and fluence of the coherent radiation. The oxidized and cleaned surfaces were analysed by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and atomic force microscopy (AFM). Laser-cleaned tungsten ribbons were used in a thermal ionization mass spectrometer (TIMS) to determine isotopic composition of neodymium atoms. The fundamental (1064 nm) and the third harmonic (355 nm) radiations were found to be the most effective in removing ThO2 particulates from the zircaloy surface. Decontamination efficiency was found to be critically dependent on the wavelength of the coherent radiation and number of exposures. The mechanism of cleaning of ThO2 particulates from the zircaloy surface at different wavelengths of the incident radiation has been explained qualitatively.
Volume 83 Issue 5 November 2014 pp 829-838
Neutrino and dark matter physics with sub-keV germanium detectors
Arun Kumar Soma Lakhwinder Singh Manoj Kumar Singh Venktesh Singh Henry T Wong on behalf of the TEXONO Collaboration
Germanium detectors with sub-keV sensitivities open a window to study neutrino physics to search for light weakly interacting massive particle (WIMP) dark matter. We summarize the recent results on spin-independent couplings of light WIMPs from the TEXONO experiment at the Kuo-Sheng Reactor Neutrino Laboratory. Highlights of the physics motivation, our R&D programme, as well as the status and plans are presented.
Volume 87 Issue 4 October 2016 Article ID 0050 Regular
Optimal control of vibrational transitions of HCl
KRISHNA REDDY NANDIPATI ARUN KUMAR KANAKATI
Control of fundamental and overtone transitions of a vibration are studied for the diatomic molecule, HCl. Specifically, the results of the effect of variation of the penalty factor on the physical attributes of the system (i.e., probabilities) and pulse (i.e., amplitudes) considering three different pulse durations for each value of the penalty factor are shown and discussed. We have employed the optimal control theory to obtain infrared pulses for selective vibrational transitions. The optimization of initial guess field with Gaussian envelope, phrased as maximization of cost functional, is done using the conjugate gradient method. The interaction of the field with the molecule is treated within the semiclassical dipole approximation. The potential and the dipole moment functions used in the calculations of control dynamics are obtained from high level ab-initio calculations.
Volume 94, 2020
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