اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدInfluence of Anomalous Dispersion on Optical Characteristics of Quantum Wells
261
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Frequency dependencies of optical characteristics (reflection, transmission and absorption of light) of a quantum well are investigated in a vicinity of interband resonant transitions in a case of two closely located excited energy levels. A wide quantum well in a quantizing magnetic field directed normally to the quantum-well plane, and monochromatic stimulating light are considered. Distinctions between refraction coefficients of barriers and quantum well, and a spatial dispersion of the light wave are taken into account. It is shown that at large radiative lifetimes of excited states in comparison with nonradiative lifetimes, the frequency dependence of the light reflection coefficient in the vicinity of resonant interband transitions is defined basically by a curve, similar to the curve of the anomalous dispersion of the refraction coefficient. The contribution of this curve weakens at alignment of radiative and nonradiative times, it is practically imperceptible at opposite ratio of lifetimes . It is shown also that the frequency dependencies similar to the anomalous dispersion do not arise in transmission and absorption coefficients.
قيم البحث
اقرأ أيضاً
Novel hysteretic effects are reported in magneto-transport experiments on lateral quantum devices. The effects are characterized by two vastly different relaxation times (minutes and days). It is shown that the observed phenomena are related to long-
lived eddy currents. This is confirmed by torsion-balance magnetometry measurements of the same 2-dimensional electron gas (2DEG) material. These observations show that the induced quantum Hall potential at the edges of the 2DEG reservoirs influences transport through the devices, and have important consequences for the magneto-transport of all lateral quantum devices.
We have studied the relevance of spin-orbit coupling to the dispersion 00009 relation of the Larmor resonance observed in inelastic light scattering and electron-spin resonance experiments on GaAs quantum wells. We show that the spin-orbit interactio
n, here described by a sum of Dresselhaus and Bychkov-Rashba terms, couples Zeeman and spin-density excitations. We have evaluated its contribution to the spin splitting as a function of the magnetic field $B$, and have found that in the small $B$ limit, the spin-orbit interaction does not contribute to the spin splitting, whereas at high magnetic fields it yields a $B$ independent contribution to the spin splitting given by $2(lambda_R^2-lambda_D^2)$, with $lambda_{R,D}$ being the intensity of the Bychkov-Rashba and Dresselhaus spin-orbit terms.
In order to explain the absence of hysteresis in ferromagnetic p-type (Cd,Mn)Te quantum wells (QWs), spin dynamics was previously investigated by Monte Carlo simulations combining the Metropolis algorithm with the determination of hole eigenfunctions
at each Monte Carlo sweep. Short-range antiferromagnetic superexchange interactions between Mn spins - which compete with the hole-mediated long-range ferromagnetic coupling - were found to accelerate magnetization dynamics if the the layer containing Mn spins is wider than the vertical range of the hole wave function. Employing this approach it is shown here that appreciate magnitudes of remanence and coercivity can be obtained if Mn ions are introduced to the quantum well in a delta-like fashion.
We present theory and calculations for coherent high-fidelity quantum control of many-particle states in semiconductor quantum wells. We show that coupling a two-electron double quantum dot to a terahertz optical source enables targeted excitations t
hat are one to two orders of magnitude faster and significantly more accurate than those obtained with electric gates. The optical fields subject to physical constraints are obtained through quantum optimal control theory that we apply in conjunction with the numerically exact solution of the time-dependent Schrodinger equation. Our ability to coherently control arbitrary two-electron states, and to maximize the entanglement, opens up further perspectives in solid-state quantum information.
Magnetotransport measurements are presented on paramagnetic (Hg,Mn)Te quantum wells (QWs) with an inverted band structure. Gate-voltage controlled density dependent measurements reveal an unusual behavior in the transition regime from n- to p-type co
nductance: A very small magnetic field of approximately 70 mT is sufficient to induce a transition into the nu = -1 quantum Hall state, which extends up to at least 10 Tesla. The onset field value remains constant for a unexpectedly wide gate-voltage range. Based on temperature and angle-dependent magnetic field measurements we show that the unusual behavior results from the realization of the quantum anomalous Hall state in these magnetically doped QWs.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
