Department of Physics

Permanent URI for this communityhttps://ir.nbu.ac.in/handle/123456789/4173

Physics is one of those departments with which North Bengal University started its journey in the year 1962. At present there are nine faculty members and ten non-teaching employees in the department. The department has active research groups in the field of (a) Liquid Crystal, (b) Relativity, Cosmology, and Astrophysics, (c) High-energy Heavy-ion Interaction and Cosmic-ray Physics, and (d) Solid-state devices. Several research projects sponsored by the DST, DAE, UGC, and Tea Research Board are running in the department. In the year 2003 the department received a financial support under the FIST programme from the DST, Govt. of India. The department offers both M.Sc. and Ph.D. courses. A semester system is followed in the M.Sc. level, with three different areas of specialization namely, Condensed Matter Physics, Electronics and Nuclear and Particle Physics, out of which a student can choose one. The annual intake capacity in M.Sc. is 40 students. In the Ph.D. programme of the department right now 25 research students are enrolled under the supervision of different faculty members. Almost all faculty members are involved in intra and inter-university national and international collaborations of scientific research. The department houses one IUCAA Resource Centre, a Data Centre for Observational Astronomy, six teaching laboratories, several research laboratories and one departmental library. From time to time the department organizes Seminars, Symposia, Conferences, Schools, Refresher Courses, and Outreach Programs.

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    Method of estimating the EAS cores of Monte Carlo showers for the GRAPES-3 experiment
    (University of North Bengal, 2024-03) Basak, Animesh
    Procedure of estimating the different extensive air shower (EAS) parameters is inherently linked to the accurate estimation of the cosmic-ray EAS cores. In EAS data analyses, the core of an EAS is estimated simultaneously with other crucial EAS parameters like shower size, shower age, etc. by fitting the lateral density data (LDD) of either the EAS charged secondaries or purely electrons with some suitably chosen lateral density function employing the maximum likelihood method. The present analysis estimates EAS cores using the LDD of electrons that fall on the scattered array detectors from the simulated EASs initiated by proton and iron primaries. Considering a densely packed detector array, including configurations akin to GRAPES-3, the research employs a straightforward weight average method (WAM) for the EAS core estimation. The findings reveal that around 95.5% of simulated showers exhibit EAS cores within a deviation range of approximately 1 m to 3 m from the actual cores of the CORSIKA Monte Carlo showers initiated by proton and iron primaries.
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    Flexible Piezoelectric Energy Harvester Based on UV Light Emitting Ce3+-Complex-P(VDF-HFP) Composite Films
    (University of North Bengal, 2024-03) Barman, Priti Sundar; Adhikary, Prakriti
    In this study, we report on the preparation of a polymer composite film with enhanced ( 99%) electroactive phases - and -phase) based on P(VDF-HFP) copolymer and Ce3+-complex. Furthermore, its utilization in piezoelectric-based flexible energy harvesting (PFEH) device fabrication has been studied, where the electrostatic interactions between the surface charges of Ce3+-complex and -CH2-/-CF2- molecular dipoles of P(VDF-HFP) via H-bonding co-operate to stabilize the electroactive phases and enhance its piezoelectric properties. PFEH generates 3 V of open circuit voltage and 0.16 A short-circuit current under the external pressure impacting amplitude of 14.20 kPa. Moreover, it can successfully charge up capacitor by repeating finger impact which indicates its potency as an efficient energy-harvesting device. Besides this, the composite film exhibits an intense photoluminescence in the UV-region that might be very promising in the area of high-performance, energy-saving, flexible, solid-state UV light emitters and fabrication of hybrid multifunctional energy harvester where mechano-luminescence phenomenon might be possible to include.
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    Na2O Doped Solid State Battery Electrolytes: Preparation and Electrical Characterization
    (University of North Bengal, 2024-03) Ram, Rakesh; Bhattacharya, Sanjib
    Na2O doped glassy electrolytes have been developed to explore their electrical transport behaviour at ambient temperature. The electrical conductivity (mixed conduction) has been studied in the light of both frequency as well as temperature. In the low frequency range, the diffusional motion of Na+ ions is expected to be the possible reason for a flat conductivity. It is also noted that the conductivity shows dispersion near the high frequency regime. The DC conductivity ( dc) and hopping frequency have been extracted from the best fitted plots of experimental data. The thermally active nature of electrical conductivity data have been studied to establish the dynamics of charge carriers via hopping conduction in sodium oxide glassy systems. Negligible small difference in pathways in the I-V characteristics in both the directions should make a sense for their applications for new generation battery-electrolyte.
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    Spectral variability in the orbital profiles of TeV Binary LSI + 61o 303 in X-Ray window using XMM - Newton Observations
    (University of North Bengal, 2024-03) Sarkar, Tamal
    LSI + 61o 303 is a high-mass X-ray binary consisting of a low-mass [M (1 - 4)M ] compact object orbiting around an early type B0 Ve star along an eccentric e = 0:7 orbit. It along with LS5039 are the only two known gamma-ray binary detected in the TeV band. Despite extensive observations the nature of this source, particularly whether it is a pulsar or a black hole (microquasar) system, is not clear. The mechanisms that lead to the multi-wavelength behavior are also uncertain. Recent approach to the study of LSI + 61o 303 has been to focus on possible correlated variability. There was an early indication that there is a correlation between the X-ray and TeV emission at the time where the latter was measurable. In a more recent observation, however, such a feature has not been found. In this work, we study the spectral variability of LSI + 61o 303 using four observations between 2001 to 2007 of XMM - Newton available from NASA archive and examine the correlation between low energy range and high energy part.
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    Spin and valley dependent transport in a biased dice lattice
    (University of North Bengal, 2024-03) Tamang, Lakpa
    We study the spin and valley-dependent transport in a spin-orbit coupled biased dice lattice. We find that the presence of a bias term and the spin-orbit interaction (SOI) give rise to the spin-split energy spectrum. The SOI couples the valley and the spin degrees of freedom, resulting in a spin and valley-resolved Berry curvature. We find a profound variation in the Berry curvature for different spin states around both valleys. The spin and valley Hall conductivities are calculated for various values of the bias term. We find the interplay between the bias term and SOI term leads to a quantum phase transition from a topological insulating phase to a trivial band insulating phase accompanied by the emergence of the valley Hall effect and the suppression of the spin Hall effect.
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    Prediction of Cross Port Output in Electro-optic Mach-Zehnder interferometer Using Artificial Neural Network
    (University of North Bengal, 2024-03) Gayen, Dilip Kumar; Chattopadhyay, Tanay
    Artificial neural networks are essential for the design and analysis of complex algorithms. We have designed a circuit with an electro-optic Mach-Zehnder interferometer (EOMZI) driven by a photodiode. The output from the EOMZI’s cross bar port is used. Then, we have developed a photonic artificial neuron based on this setup. The outputs are validated using MATLAB, and the Artificial neural networks successfully generate the sigmoid function corresponding to the EOMZI switch’s cross port.
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    Brief overview of Nanomechanical Qubits
    (University of North Bengal, 2024-03) Samanta, Chandan
    Qubits are the building blocks for quantum computers and quantum information processing. However, there is a great deal of dispute over the most ideal types of qubits. The nanomechanical qubit might be one potential addition to the qubit platforms. Here, we briefly outline the underlying physical principle of a nanomechanical qubit, where the mechanical vibrations stores the information
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    Exactly Solvable Pöschl-Teller Potential
    (University of North Bengal, 2024-03) Dutta, Parikshit
    Revisit a well known quantum mechanical problem, the trigonometric Pöschl-Teller potential, which is an exactly solvable one-dimensional problem. The potential appears in many physical systems of study and thus the technique of solution is interesting and important for students and readers to know. We wish to elaborate on this in this article.
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    Short course on the Su-Schrieffer-Heeger model
    (University of North Bengal, 2024-03) Ghosh, Tarun Kanti
    Review various topological properties of a dimer Su-Schrieffer-Heeger tight-binding model. Exact analytical expressions of the energy spectrum and corresponding eigenstates for any choice of system parameters are provided. We discuss the system’s parity, time-reversal, and chiral symmetries. The system undergoes a topological phase transition while tuning the hopping parameters. The topological phase is associated with the presence of the boundary modes and establishes the bulk-boundary correspondence.
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    Recent Efforts Towards Understanding the Early Universe from a Fundamental Quantum Perspective
    (University of North Bengal, 2024-03) Modak, Sujoy K.
    Observable universe is fundamentally inhomogeneous and anisotropic. Quantum description of the generation of these inhomogeneities and anisotropies is ill-understood and unsatisfactory. After providing a brief account of the standard approach of the generation of the classical density perturbations starting from the quantum fluctuations of inflaton field, I critically review various assumptions which are crucial for the success of this description, and point out various shortcomings around it. I also discuss the basic ideas and recent works by using an alternative path to overcome those shortcomings which is motivated by the so-called Collapse Model interpretation of quantum mechanics. Inspired by these works, I argue the necessity of constructing a class of manifestly inhomogeneous and anisotropic quantum states after inflation and discuss my recent works which provide one such prescription of building such a state, called the T-vacuum, defined in the radiation dominated stage of the early universe.