S. Sengupta’s research while affiliated with Jadavpur University and other places

... Quantum Brownian motion (QBM, Caldeira and Leggett 1983) is paradigmatic for the field of open quantum systems theory (Breuer and Petruccione 2002). Description of quantum decoherence (Giulini et al 1996, Dugić 2004 as well as modeling of -quantum dissipation‖ is directly provided for QBM as a realistic physical situation with the well-defined classical counterpart. The usefulness of the QBM model places the model at the heart of applications regarding the nano-and mesoscopic systems and some artificial setups as well as regarding the related emerging technologies, e.g. ...

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The first and second moments for the quantum Brownian planar rotator in external harmonic classical field

... Venkataraman and Sahni, [124] and corrected by others in subsequent work. [212,213] The necessary molecular derivatives (both rotational and translational) are expressed as appropriate sums involving the corresponding derivatives applied to the interaction sites, which can be evaluated analytically. ...

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Highly Efficient Molecular Simulation Methods For Evaluation Of Thermodynamic Properties Of Crystalline Phases

... However, a note on a comparison of these results to classical results may be worthwhile. Despite previous reports [33][34][35] on the difference between the classical and quantum mechanical definitions of scattering cross sections and the problem of classical limit, the general derivation of classical results from the quantum mechanics, i.e., the reduction theory, is still afar. While such calculations are outside of the current work, to compare the classical and quantum results, one may consider the more tangible case of a finite nanostructure. ...

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Quantum states of cylindrical surface charge density for modeling plasmonic circuit elements: Nanowires, nanorods, cavities, and waveguides

... Das Modell wurde in der Literatur genutzt, um die Eigenschaften von nanogefüllten teilkristallinen Thermoplasten nachzuvollziehen [155,156]. Unter Annahme des klassischen 2-Phasenmodells wurde das Modell zudem so modifiziert, dass das anisotrope elastische Verhalten nach starker Verstreckung beschrieben werden kann [157]. Weiterhin wurde das Modell erfolgreich angepasst, um das elastische Verhalten teilkristalliner Thermoplaste unter Berücksichtigung des 3-Phasenmodells zu beschreiben. ...

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Kristallisation von Polyestern unter theoretischen und prozessnahen thermischen Randbedingungen

... In particular, one can try to directly evaluate the world-sheet integrals in closed-string genusone amplitudes thus obtaining lattice-sum representations of MGFs [1][2][3][4]18]. Although it is possible to extract the asymptotic expansion at the cusp τ → i∞ from some of these lattice-sum representations [39,48], this is nonetheless a hard task suggesting that a different approach might in general be necessary. ...

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To the cusp and back: resurgent analysis for modular graph functions

... The Aharonov-Bohm (AB) effect is an authentic quantum phenomenon and was first considered in [19,18,1]. There are many discussions about the justification of the famous Aharonov-Bohm Hamiltonian and interpretations (see, for instance, [2,7,8,9,11,15,20,22,26,28,30] and references therein); the questions are particularly interesting for the more realistic case of solenoids S of radii greater than zero. Sometimes it involves the quantization in multiply connected regions, and the main points to be clarified are the presence of the vector potential A in the operator action (occasionally in regions with no magnetic field), and the (natural) choice of Dirichlet boundary conditions at the solenoid border. ...

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Impenetrability of Aharonov–Bohm Solenoids: Proof of Norm Resolvent Convergence

... (6) have also been used in the literature to simulate pressure effects on atoms with the extreme pressure polarized continuum model (XP-PCM). 62,[90][91][92][93][94][95][96][97] Again, from the Schrödinger equation, while the first derivative is now continuous as long as V 0 is finite, 98,99 it appears that the discontinuity in the potential of eq. (6) is reflected by a finite jump in the second derivative of the resulting orbital. ...

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Atomic Confinement Potentials

... We show that this can be accomplished via the violation of a Bell's inequality in which the spin and the positions of the mass are measured. This violation will also prove the nonclassicality of a large mass in terms of quantum contextuality [34,35]. ...

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Massive spatial qubits: Testing macroscopic nonclassicality and Casimir entanglement

... With the rotational invariance and equilibrium conditions correctly applied, the phonon dispersions of 158 materials become real and display a quadratic ZA branch in the longwavelength limit. The remaining 87 materials are either dynamically unstable (54) or require tighter numerical convergence (33). ...

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General invariance and equilibrium conditions for lattice dynamics in 1D, 2D, and 3D materials

... This phase space describes semiclassical electron dynamics in a magnetic Bloch band, with periodic potential in an external magnetic field and Berry curvature [7]. This fluid dynamics is relevant in electron hydrodynamics in condensed matter, where electron flow obeys hydrodynamic laws instead of Ohmic [8]. Generically electrons in metals act as nearly-free Fermi gas with a large mean free path for electron-electron collision. ...

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Spinning black hole in a fluid