Binding energy of an off-center donor impurity in ellipsoidal quantum dot with parabolic confinement potential

2011 ◽  
Vol 406 (2) ◽  
pp. 241-244 ◽  
Author(s):  
E. Sadeghi ◽  
A. Avazpour
Keyword(s):  
Binding Energy ◽  
Quantum Dot ◽  
Donor Impurity ◽  
Confinement Potential ◽  
Ellipsoidal Quantum Dot ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential

THE EFFECTS OF QUANTUM CONFINEMENT ON THE BINDING ENERGY OF HYDROGENIC IMPURITIES IN A SPHERICAL QUANTUM DOT

2006 ◽  
Vol 20 (18) ◽  
pp. 1127-1134 ◽  
Author(s):  
A. JOHN PETER
Keyword(s):  
Binding Energy ◽  
Quantum Dot ◽  
Shallow Donor ◽  
Donor Impurity ◽  
Hydrogenic Impurity ◽  
Spherical Quantum Dot ◽  
Impurity Position ◽  
Mass Approximation ◽  
Donor Binding Energy ◽  
Parabolic Confinement

The binding energy of a shallow hydrogenic impurity of a spherical quantum dot confined by harmonic oscillator-like and by rectangular well-like potentials, using a variational procedure within the effective mass approximation, has been determined. The calculations of the binding energy of the donor impurity as a function of the system geometry, and the donor impurity position have been investigated. The binding energy of shallow donor impurity depends not only on the quantum confinements but also on the impurity position. Our results reveal that (i) the donor binding energy decreases as the dot size increases irrespective of the impurity position, and (ii) the binding energy values of rectangular confinement are larger than the values of parabolic confinement and (iii) the rectangular confinement is better than the parabolic confinement in a spherical quantum dot.

scholarly journals Magnetocaloric Effect in an Antidot : The Effect of the Aharonov-Bohm Flux and Antidot Radius

2018 ◽  
Author(s):  
Oscar A. Negrete ◽  
Francisco J. Peña ◽  
Patricio Vargas
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Magnetocaloric Effect ◽  
Control Parameter ◽  
Energy Levels ◽  
Oscillatory Behaviour ◽  
Confinement Potential ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential ◽  
Aharonov Bohm

In this work, we report the magnetocaloric effect (MCE) in a quantum dot corresponding to an electron interacting with an antidot, under the effect of an Aharonov-Bohm flux subjected to a parabolic confinement potential. We use the Bogachek and Landman model, which additionally allows the study of quantum dots with Fock-Darwin energy levels for vanishing antidot radius and flux. We find that the Aharonov-Bohm flux (AB-flux) strongly controls the oscillatory behaviour of the MCE, thus acting as a control parameter for the cooling or heating of the magnetocaloric effect. We propose a way to detect AB-flux by measuring temperature differences.

Coherent nonlinear low-frequency Landau–Zener tunneling induced by magnetic control of a spin qubit in a quantum wire

2018 ◽  
Vol 16 (06) ◽  
pp. 1850049
Author(s):  
S. E. Mkam Tchouobiap ◽  
J. E. Danga ◽  
R. M. Keumo Tsiaze ◽  
L. C. Fai
Keyword(s):  
Quantum Wire ◽  
Modulation Frequency ◽  
Strong Dependence ◽  
Rabi Oscillation ◽  
Low Frequency ◽  
Dynamical Evolution ◽  
Quantum Bit ◽  
Confinement Potential ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential

This paper presents nonlinear Landau–Zener (LZ) tunneling of an electron spin in an accelerating optical parabolic potential, manifested in a heterostructure quantum wire subjected to a periodic magnetic field comprising a spike and a homogeneous part. In this context, driving the two states of a pure nonlinear two-level quantum bit (qubit) system through an avoided level crossing can result in nontrivial dynamics, especially with and without considering a parabolic confinement potential characterized by a curvature confinement potential. We report two striking nonadiabatic and adiabatic scenarios in low modulation frequency limit which appear when such strength modulation occurs. Firstly, the changes of the amplitude of the driving field without considering a parabolic confinement potential act as a perturbation which mixes the spin states. Here, the dynamical evolution of the tunneling probabilities of the nonadiabatic populations under investigation is analyzed. Secondly, for strong fields and strong dependence of a parabolic confinement potential, the two diabatic states do not cross but present anti-crossing phenomenon as the time tends to infinity, describing an adiabatic transition. However, if the field strength in a wire is weak enough, the level separation of a qubit state switches abruptly around the crossing point, and LZ tunneling applies to the whole dynamical range, from adiabatic to fully nonadiabatic crossing. Locally, the tunneling process can be seen as a two-level system (TLS) undergoing a Rabi oscillation. These results open new prospects for the use of quantum interferences in spin–based devices.

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