Browsing by Author "Hawrylak, P"

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Interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields
(2004-09-01)
Hawrylak, P
;
Sheng, W
;
Cheng, S
;
電子物理學系
;
Department of Electrophysics
Theory of optical properties of interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields is discussed. In two dimensions and the lowest Landau level, hidden symmetries control the interaction of the interacting system with light. By confining electrons and holes into quantum dots hidden symmetries can be removed and the excitation spectrum of electrons and excitons can be observed. We discuss a theory electronic and of excitonic quantum Hall droplets at a filling factor nu = 2. For an excitonic quantum Hall droplet the characteristic emission spectra are predicted to be related to the total spin of electron and hole configurations. For the electronic droplet the excitation spectrum of the droplet can be mapped out by measuring the emission for increasing number of electrons.
Quantum Hall droplet at excitonic filling factor nu=2 in a self-assembled quantum dot
(2006-01-01)
Cheng, SJ
;
Hawrylak, P
;
電子物理學系
;
Department of Electrophysics
We present a theory of excitonic quantum Hall droplet (EXQHD) at filling factor nu=2 in a self-assembled quantum dot (SAD) subject to strong perpendicular magnetic field B. Using exact diagonalization technique we determine the ground and excited states, the stability against spin flips, and the optical emission spectrum of the nu=2 EXQHDs. In contrast with one-component electronic droplets, the singlet-singlet nu=2 EXQHD is found to be intrinsically correlated, and stable even in high magnetic fields due to the neutrality of exciton. The characteristic spin related emission spectrum and its magnetic field evolution from the EXQHD are predicted.
Theory of excitonic artificial atoms: InGaAs/GaAs quantum dots in strong magnetic fields
(2003-12-01)
Cheng, SJ
;
Sheng, WD
;
Hawrylak, P
;
電子物理學系
;
Department of Electrophysics
We develop a theory of excitonic artificial atoms in strong magnetic fields. The excitonic atoms are formed by N electrons and holes confined in a quantum dot. The single-particle levels are described by the Fock-Darwin spectrum in a magnetic field. The magnetic field induces crossing of energy levels and allows us to engineer degenerate shells. We apply exact diagonalization techniques to calculate the magnetic-field evolution of the ground state of the N-electron-hole complex and its emission spectra. We focus on degenerate shells and show that excitons condense into correlated states due to hidden symmetry. We relate the Fock-Darwin spectrum, hidden symmetries, and direct and exchange interaction among particles to the emission spectra as a function of number of electron-hole pairs (excitation power) and magnetic field.
Theory of excitonic filling factor v=2 quantum Hall droplet in self-assembled quantum dots
(2005)
Chen, SJ
;
Sheng, WD
;
Hawrylak, P
;
電子物理學系
;
Department of Electrophysics
We present a theory of excitonic quantum Hall droplet (EXQHD) at filling factor v = 2 in a self-assembled quantum dot subject to a strong perpendicular magnetic field B. Using the method of configuration interaction the ground and excited states, the stability against spin flips, and die optical emission spectrum of v = 2 EXQHD are calculated in both semi-analytical and numerical manner. The v = 2 EXQHD is found to be stable and its characteristic spin related emission pattern is identified.