Browsing by Author "Moulopoulos, Konstantinos"
Now showing items 21-40 of 40
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Conference Object
Landau level physics in a quantum well: New singular features in magnetization and violations of de Haas-van Alphen periodicities
Konstantinou, Georgios; Moulopoulos, Konstantinos (2011)Analytical calculations based on a Landau Level (LL) picture are reported for an interface (with a finite-width Quantum Well (QW)) and for a fully three-dimensional charged quantum electronic system in an external magnetic ...
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Linear dynamic polarizability and the absorption spectrum of an exciton in a quantum ring in a magnetic field
Ghazaryan, A. V.; Djotyan, Anahit P.; Moulopoulos, Konstantinos; Kirakosyan, Albert A. (2011)The problem of an electron-hole system interacting through a contact potential and moving in a one-dimensional quantum ring threaded by an Aharonov-Bohm flux is considered, with respect to the system's energetics as well ...
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Magnetic-field-induced localization in networks with the T3 geometry
Moulopoulos, Konstantinos; Constantinou, Martha G. (2002)By following an exact analytical procedure we study the transmission properties of a network of quantum wires arranged in a so-called T3 configuration and in the presence of a perpendicular magnetic field. It is shown that ...
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Magnetoexcitons in semiconductor quantum rings with complicated (Kane's) dispersion law
Avetisyan, A. A.; Ghazaryan, A. V.; Djotyan, Anahit P.; Klrakosyan, A. A.; Moulopoulos, Konstantinos (2009)The influence of the nonparabolicity of charge carriers dispersion law (Kane's dispersion) on a magnetoexciton energy spectrum in InSb quantum rings is theoretically investigated. The analytical expression for the energy ...
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Many-body theory of paired electron crystals
Moulopoulos, Konstantinos; Ashcroft, N. W. (1993)We develop a variational many-body description of low-density three-dimensional paired electron crystals. Among the ground states of such crystals we find that coherent paired supersolids (resonant spin states) and true ...
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New low density phase of interacting electrons: The paired electron crystal
Moulopoulos, Konstantinos; Ashcroft, N. W. (1992)A variational method shows that for a range of densities the compensated low density interacting electron system possesses a ground-state crystalline phase with L=0 spin-singlet pairs and with an energy lower than the ...
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Non-peturbative density expansions for extended Coulomb systems
Moulopoulos, Konstantinos (2000)We present a general non-perturbative argument that combines the Pauli and virial theorems for a multicomponent translationally invariant Coulombic system of fermions at zero temperature, and which by an iteration procedure ...
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Nonlinear properties of gated graphene in a strong electromagnetic field
Avetisyan, A. A.; Djotyan, Anahit P.; Moulopoulos, Konstantinos (2017)We develop a microscopic theory of a strong electromagnetic field interaction with gated bilayer graphene. Quantum kinetic equations for density matrix are obtained using a tight binding approach within second quantized ...
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Nonlocal phases of local quantum mechanical wavefunctions in static and time-dependent Aharonov-Bohm experiments
Moulopoulos, Konstantinos (2010)We show that the standard Dirac phase factor is not the only solution of the usual gauge transformation equations. The full form of a general gauge function (that connects systems that move in different sets of scalar and ...
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Conference Object
Novel nonlocal gauge functions in electrodynamics and their effect on quantum mechanical phases
Moulopoulos, Konstantinos (2011)We point to previously overlooked solutions of the standard gauge transformation equations of Electrodynamics: the generalized "gauge functions" go beyond the usual Dirac phase factors (spatial or temporal integrals of ...
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One-component charged systems as a limiting case of quantal two-component mixtures - A bifurcation procedure for a many-body system
Moulopoulos, Konstantinos; Ashcroft, N. W. (1996)The standard model problem of a three-dimensional fully interacting electron gas in a uniform compensating background is shown to result from a procedure starting at the operator leval with a fully quantum mechanical ...
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Pairing ground states in fermion systems: A static method
Moulopoulos, Konstantinos; Ashcroft, N. W. (1990)We present a static recursive method that can straightforwardly be applied to variational treatments of canonical many-body systems whose ground states generally exhibit pairing or higher clustering correlations. We ...
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Phase transitions in a few-electron quantum dot in a magnetic field: Wigner phases and broken-symmetry spin-singlet states
Avetisyan, A. A.; Moulopoulos, Konstantinos; Djotyan, Anahit P. (2008)We develop a variational many-body approach within a second quantized formulation for a few-electron system in a parabolic two-dimensional quantum dot (QD). By way of application, the nature of the ground state of a ...
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Role of phason defects on the conductance of a one-dimensional quasicrystal
Moulopoulos, Konstantinos; Roche, S. (1996)We have studied the influence of a particular kind of phason defect on the Landauer resistance of a Fibonacci chain. Depending on parameters, we sometimes find the resistance to decrease upon introduction of defect or ...
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Scaling relations for two-component charged systems: Application to metallic hydrogen
Moulopoulos, Konstantinos; Ashcroft, N. W. (1990)We derive exact scaling relations for the energy and pair-correlation functions of a neutral two-component system of charged nonrelativistic particles in its ground state. These are obtained under general conditions through ...
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Topological Proximity Effect: A Gauge Influence from Distant Fields on Planar Quantum-Coherent Systems
Moulopoulos, Konstantinos (2015)A quantum system that lies nearby a magnetic or time-varying electric field region, and that is under periodic boundary conditions parallel to the interface, is shown to exhibit a “hidden” Aharonov-Bohm effect (magnetic ...
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Transmission resonance in an infinite strip of phason defects of a Penrose approximant network
Moulopoulos, Konstantinos; Roche, S. (1995)An exact method that analytically provides transfer matrices in finite networks of quasicrystalline approximants of any dimensionality is discussed. We use these matrices in two ways: (a) to exactly determine the band ...
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Conference Object
Tunable excitons in gated graphene systems
Djotyan, Anahit P.; Avetisyan, A. A.; Moulopoulos, Konstantinos (SPIE, 2017)We develop a microscopic theory of a strong electromagnetic radiation interaction with bilayer graphene where an energy gap is opened by a static electric field perpendicular to graphene planes. We show that an adiabatic ...
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Two interacting charged particles in an Aharonov-Bohm ring: Bound state transitions, symmetry breaking, persistent currents, and Berry's phase
Moulopoulos, Konstantinos; Constantinou, Martha G. (2004)By using a Green's function procedure we determine exactly the energy spectrum and the associated eigen-states of a system of two oppositely charged particles interacting through a contact potential and moving in a ...
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Unpaired and spin-singlet paired states of a two-dimensional electron gas in a perpendicular magnetic field
Polini, Marco; Moulopoulos, Konstantinos; Davoudi, Bahman; Davoudi, B.; Tosi, Mario P. (2002)We present a variational study of both unpaired and spin-singlet paired states induced in a two-dimensional electron gas at low density by a perpendicular magnetic field. It is based on an improved circular-cell approximation ...