Browsing by Author "Pandey, N."

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Characteristics of vibration at failure and its relation to rock properties during tensile failure
(Books and Journals Private Ltd., 2020) Pal, S.K.; Pandey, N.; Tripathi, A.K.
The paper describes the study carried out to determine the relationships between the amount of vibrations that happen inside the rock at the time of failure under tensile loading and different rock properties such as uniaxial compressive strength, uniaxial tensile strength, Young’s modulus, cohesion, angle of internal friction and density. It is then tried to interpret what are the factors that affect the vibrations and the time to failure. To capture the vibrations piezoelectric sensors are used which capture the acoustic signals and convert them into electric signals. With the help of Picoscope, it was then possible to recover the acoustic signals. At the time of failure, the peak voltage (h) was recorded along with the span of time the rock took to fail (w). The h/w ratio was then obtained and used to relate it with different rock properties. h/w ratio is the measure of how much vibrations happen inside the rock and for what amount of time. It was observed to be highly related to uniaxial tensile strength, angle of internal friction and rock density. © 2020, Books and Journals Private Ltd.. All rights reserved.
Circuit Complexity in Interacting Quenched Quantum Field Theory
(MDPI, 2023) Choudhury, S.; Gharat, R.M.; Mandal, S.; Pandey, N.
In this work, we explore the effects of quantum quenching on the circuit complexity of quenched quantum field theory with weakly coupled quartic interactions. We use the invariant operator method under a perturbative framework to compute the ground state of this system. We give the analytical expressions for specific reference and target states using the ground state of the system. Using a particular cost functional, we show the analytical computation of circuit complexity for the quenched and interacting field theory. Furthermore, we give a numerical estimate of circuit complexity with respect to the quench rate, (Formula presented.), for two coupled oscillators. The parametric variation in the unambiguous contribution of the circuit complexity for an arbitrary number of oscillators has been studied with respect to the dimensionless parameter (Formula presented.)). We comment on the variation in the circuit complexity for different values of coupling strength, different numbers of oscillators and even in different dimensions. © 2023 by the authors.
Circuit Complexity in Z2 EEFT
(MDPI, 2023) Adhikari, K.; Choudhury, S.; Kumar, S.; Mandal, S.; Pandey, N.; Roy, A.; Sarkar, S.; Sarker, P.; Shariff, S.S.
Motivated by recent studies of circuit complexity in weakly interacting scalar field theory, we explore the computation of circuit complexity in (Formula presented.) Even Effective Field Theories ((Formula presented.) EEFTs). We consider a massive free field theory with higher-order Wilsonian operators such as (Formula presented.), (Formula presented.), and (Formula presented.) To facilitate our computation, we regularize the theory by putting it on a lattice. First, we consider a simple case of two oscillators and later generalize the results to N oscillators. This study was carried out for nearly Gaussian states. In our computation, the reference state is an approximately Gaussian unentangled state, and the corresponding target state, calculated from our theory, is an approximately Gaussian entangled state. We compute the complexity using the geometric approach developed by Nielsen, parameterizing the path-ordered unitary transformation and minimizing the geodesic in the space of unitaries. The contribution of higher-order operators to the circuit complexity in our theory is discussed. We also explore the dependency of complexity on other parameters in our theory for various cases. © 2022 by the authors.
Entanglement in interacting quenched two-body coupled oscillator system
(American Physical Society, 2022) Choudhury, S.; Gharat, R.M.; Mandal, S.; Pandey, N.; Roy, A.; Sarker, P.
In this work, we explore the effects of a quantum quench on the entanglement measures of a two-body coupled oscillator system having quartic interaction. We use the invariant operator method, under a perturbative framework, for computing the ground state of this system. We give the analytical expressions for the total and reduced density matrix of the system having non-Gaussian, quartic interaction terms. Using this reduced density matrix, we show the analytical calculation of two entanglement measures viz., Von Neumann entanglement entropy using replica trick and Renyi entanglement entropy. Further, we give a numerical estimate of these entanglement measures with respect to the dimensionless parameter (t/δt) and show its behavior in the three regimes, i.e., late time behavior, around the quench point and the early time behavior. We comment on the variation of these entanglement measures for different orders of coupling strength. The variation of Renyi entropy of different orders has also been discussed. © 2022 authors. Published by the American Physical Society.
Facile hydrothermal synthesis of vanadium disulfide nanomaterial for supercapacitor application
(SPIE, 2023) Mandal, A.; Pandey, N.; Pandey, S.K.; Yadav, A.K.; Chakrabarti, S.
Vanadium disulfide (VS2) is a prominent metallic member of transition metal dichalcogenides (TMDs) family and has already demonstrated its flair in energy storage device applications such as supercapacitors and batteries. In this work, we have synthesized hexagonal shape VS2 nanomaterial using a facile one step hydrothermal route and investigated the phase, morphology and structural properties of the material. The formation of phase has been confirmed from the X-ray diffraction (XRD) plot by correlating with the database of Joint Committee on Powder Diffraction Standards (JCPDS) 00-036-1139 of 1T VS2. Further, the crystalline behavior of VS2 nanomaterial can be seen from the high resolution transmission electron microscopy (HRTEM) measurement. Moreover, the morphology of the synthesized material is obtained from the field emission gun-scanning electron microscopy (FEG-SEM). Also, the characteristic Raman peaks of 1T VS2 at 140.3 cm-1 and 192.3 cm-1 have been observed from the Raman spectrum indicating the metallic behavior of synthesized material. The peak at 281.8 cm-1 is attributed to the in-plane vibrational mode (E2g1) while the peak at 404.5 cm-1 represents the out-of-plane vibrational mode (A1g) of V-S bond. The Fourier transform infrared (FTIR) spectrum shows the V-S-V and V=S vibrational modes around 534 cm-1 and 982 cm-1 respectively. The study introduces a low cost, large scale, highly crystalline, and metallic VS2 nanomaterial with potential application for next generation supercapacitors and other energy storage devices. Â© 2023 SPIE.
Schwinger–Keldysh Path Integral Formalism for a Quenched Quantum Inverted Oscillator
(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Choudhury, S.; Dey, S.; Gharat, R.M.; Mandal, S.; Pandey, N.
In this work, we study the time-dependent behavior of quantum correlations of a system of an inverted oscillator governed by out-of-equilibrium dynamics using the well-known Schwinger–Keldysh formalism in the presence of quantum mechanical quench. Considering a generalized structure of a time-dependent Hamiltonian for an inverted oscillator system, we use the invariant operator method to obtain its eigenstate and continuous energy eigenvalues. Using the expression for the eigenstate, we further derive the most general expression for the generating function as well as the out-of-time-ordered correlators (OTOCs) for the given system using this formalism. Further, considering the time-dependent coupling and frequency of the quantum inverted oscillator characterized by quench parameters, we comment on the dynamical behavior, specifically the early, intermediate and late time-dependent features of the OTOC for the quenched quantum inverted oscillator. Next, we study a specific case, where the system of an inverted oscillator exhibits chaotic behavior by computing the quantum Lyapunov exponent from the time-dependent behavior of OTOCs in the presence of the given quench profile. © 2024 by the authors.