A theoretical study on the optical properties of a quantum well with short-range bottomless exponential potential

2019 ◽  
Vol 33 (20) ◽  
pp. 1950225
Author(s):  
F. Ungan ◽  
M. E. Mora-Ramos ◽  
S. Sakiroglu ◽  
H. Sari ◽  
I. Sökmen
Keyword(s):  
Quantum Well ◽  
Short Range ◽  
Bound States ◽  
Peak Position ◽  
Resonant Peak ◽  
Exponential Potential ◽  
Nonlinear Properties ◽  
Mass Approximation ◽  
Electric And Magnetic Fields ◽  
Applied Fields

The effects of external applied fields on the electron-related optical nonlinear properties in a short-range bottomless exponential potential quantum well are investigated. The potential profile behaves as inverse square root in the vicinity of the origin and vanishes exponentially toward infinity, supporting a finite number of bound states whose energies and wave functions are determined within the effective-mass approximation. The linear, third-order nonlinear and total optical absorption coefficients (TOACs) as well as the coefficient of relative refractive index changes (RRICs) of the system are calculated from the expressions derived in the framework of the compact density matrix approach. The results obtained after numerical calculations show that with the effect of the static electric and magnetic fields (high-frequency THz laser field), the resonant peak position of the optical response shifts toward higher (lower) energies and the magnitude of the peak increases.

EXCITONS IN A NARROW PARABOLIC QUANTUM WELL UNDER EXTERNAL FIELDS

2003 ◽  
Vol 17 (24) ◽  
pp. 1253-1264 ◽  
Author(s):  
ECATERINA C. NICULESCU ◽  
LILIANA BURILEANU
Keyword(s):  
Spatial Distribution ◽  
Magnetic Fields ◽  
Electric Field ◽  
Quantum Well ◽  
Effective Mass ◽  
Conduction Band ◽  
Quantum Confinement ◽  
Mass Approximation ◽  
Low Field ◽  
Electric And Magnetic Fields

The effects of electric and magnetic fields on the ground (1S-like) and excited (2S-like) states of an exciton in a narrow GaAs/Al x Ga 1-x As parabolic quantum well are studied. The effective-mass approximation within a perturbation-variational scheme is adopted. We find that the hole-mass anisotropy and nonparabolicity of the conduction band significantly modify the electron properties in such structures in which the quantum confinement plays a fundamental role. The effect of the electric field on the spatial distribution of the electron and hole is also investigated. In the low field regime, the diamagnetic shift of the exciton energies is calculated.

LINEAR AND NONLINEAR INTERSUBBAND OPTICAL ABSORPTION OF FINITE AND INFINITE SEMI-PARABOLIC QUANTUM WELLS

2011 ◽  
Vol 25 (07) ◽  
pp. 497-507 ◽  
Author(s):  
M. J. KARIMI ◽  
A. KESHAVARZ ◽  
A. POOSTFORUSH
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Optical Absorption ◽  
Quantum Well ◽  
Quantum Wells ◽  
Resonant Peak ◽  
Energy Eigenvalues ◽  
Finite Case ◽  
Infinite Case ◽  
Index Changes

In this work, the optical absorption coefficients and the refractive index changes for the infinite and finite semi-parabolic quantum well are calculated. Numerical calculations are performed for typical GaAs / Al x Ga 1-x As semi-parabolic quantum well. The energy eigenvalues and eigenfunctions of these systems are calculated numerically. Optical properties are obtained using the compact density matrix approach. Results show that the energy eigenvalues and the matrix elements of the infinite and finite cases are different. The calculations reveal that the resonant peaks of the optical properties of the finite case occur at lower values of the incident photon energy with respect to the infinite case. Results indicate that the maximum value of the refractive index changes for the finite case are greater than that of the infinite case. Our calculations also show that in contrast to the infinite case, the resonant peak value of the total absorption coefficient in the case of the finite well is a non-monotonic function of the semi-parabolic confinement frequency.

The effects of the intense laser field on bound states in Ga x In1- x N y As1- y N/GaAs single quantum well

2011 ◽  
Vol 80 (1) ◽  
pp. 89-93 ◽  
Author(s):  
F. Ungan ◽  
E. Kasapoglu ◽  
C. A. Duque ◽  
U. Yesilgul ◽  
S. Şakiroglu ◽  
...  
Keyword(s):  
Quantum Well ◽  
Laser Field ◽  
Bound States ◽  
Intense Laser ◽  
Single Quantum ◽  
Intense Laser Field ◽  
Single Quantum Well

scholarly journals The structure of the native cardiac thin filament at systolic Ca2+ levels

2021 ◽  
Vol 118 (13) ◽  
pp. e2024288118
Author(s):  
Cristina M. Risi ◽  
Ian Pepper ◽  
Betty Belknap ◽  
Maicon Landim-Vieira ◽  
Howard D. White ◽  
...  
Keyword(s):  
Cardiac Muscle ◽  
Binding Sites ◽  
Short Range ◽  
Bound States ◽  
Thin Filament ◽  
Narrow Range ◽  
The Other ◽  
Thin Filaments ◽  
Troponin Complex ◽  
Myosin Binding

Every heartbeat relies on cyclical interactions between myosin thick and actin thin filaments orchestrated by rising and falling Ca2+ levels. Thin filaments are comprised of two actin strands, each harboring equally separated troponin complexes, which bind Ca2+ to move tropomyosin cables away from the myosin binding sites and, thus, activate systolic contraction. Recently, structures of thin filaments obtained at low (pCa ∼9) or high (pCa ∼3) Ca2+ levels revealed the transition between the Ca2+-free and Ca2+-bound states. However, in working cardiac muscle, Ca2+ levels fluctuate at intermediate values between pCa ∼6 and pCa ∼7. The structure of the thin filament at physiological Ca2+ levels is unknown. We used cryoelectron microscopy and statistical analysis to reveal the structure of the cardiac thin filament at systolic pCa = 5.8. We show that the two strands of the thin filament consist of a mixture of regulatory units, which are composed of Ca2+-free, Ca2+-bound, or mixed (e.g., Ca2+ free on one side and Ca2+ bound on the other side) troponin complexes. We traced troponin complex conformations along and across individual thin filaments to directly determine the structural composition of the cardiac native thin filament at systolic Ca2+ levels. We demonstrate that the two thin filament strands are activated stochastically with short-range cooperativity evident only on one of the two strands. Our findings suggest a mechanism by which cardiac muscle is regulated by narrow range Ca2+ fluctuations.

Bound States of Spinless Particles in a Short-Range Potential

2015 ◽  
Vol 70 (4) ◽  
pp. 245-249 ◽  
Author(s):  
Hassan Hassanabadi ◽  
Antonio Soares de Castro
Keyword(s):  
Short Range ◽  
Bound States ◽  
Bound State ◽  
Scalar Coupling ◽  
Spinless Particle ◽  
Vector Coupling ◽  
Short Range Potential ◽  
Range Potential ◽  
Constraint Relation ◽  
Potential Parameters

AbstractWith a general mixing of vector and scalar couplings in a two-dimensional world, a short-range potential is used to explore certain features of the bound states of a spinless particle. Bound-state solutions are found in terms of the Gauss hypergeometric series when the potential parameters obey a certain constraint relation limiting the dosage of a vector coupling. The appearance of the Schiff–Snyder–Weinberg effect for a strong vector coupling and a short-range potential as well as its suppression by the addition of a scalar coupling is discussed.

Magneto-thermoelectric effects in two-dimensional quantum well: role of short-range potential

2009 ◽  
Vol 81 (1) ◽  
pp. 015701 ◽  
Author(s):  
F M Hashimzade ◽  
Kh A Hasanov ◽  
B H Mehdiyev ◽  
S Cakmak
Keyword(s):  
Quantum Well ◽  
Short Range ◽  
Two Dimensional ◽  
Thermoelectric Effects ◽  
Short Range Potential ◽  
Range Potential

Quantum-Well Bound States in Graphene Heterostructure Interfaces

2021 ◽  
Vol 127 (8) ◽  
Author(s):  
Zhongwei Dai ◽  
Zhaoli Gao ◽  
Sergey S. Pershoguba ◽  
Nikhil Tiwale ◽  
Ashwanth Subramanian ◽  
...  
Keyword(s):  
Quantum Well ◽  
Bound States
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