Browsing by Author "Brandes, T"

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Current detection of superradiance and induced entanglement of double quantum dot excitons
(2003-04-25)
Chen, YN
;
Chuu, DS
;
Brandes, T
;
電子物理學系
;
Department of Electrophysics
We propose to measure the superradiance effect by observing the current through a semiconductor double-dot system. An electron and a hole are injected separately into one of the quantum dots to form an exciton and then recombine radiatively. We find that the stationary current shows oscillatory behavior as one varies the interdot distance. The amplitude of oscillation can be increased by incorporating the system into a microcavity. Furthermore, the current is suppressed if the dot distance is small compared to the wavelength of the emitted photon. This photon trapping phenomenon generates the entangled state and may be used to control the emission of single photons at predetermined times.
Decay rate and renormalized frequency shift of a quantum wire Wannier exciton in a planar microcavity
(2001-09-15)
Chen, YN
;
Chuu, DS
;
Brandes, T
;
Kramer, B
;
電子物理學系
Super-radiant decay rate and frequency shift of a Wannier exciton in a one-dimensional quantum wire are studied. It is shown that the dark-mode exciton can be examined experimentally when the quantum wire is embedded in a planar microcavity. It is also found that the decay rate is greatly enhanced as the cavity length L-c is equal to the multiple wavelength of the emitted photon. Similar to its decay-rate counterpart, the frequency shift also shows discontinuities at resonant modes.
Proposal for teleportation of charge qubits via super-radiance
(2005-08-18)
Chen, YN
;
Li, CM
;
Chuu, DS
;
Brandes, T
;
電子物理學系
A scheme is proposed to teleport charge qubits via super-radiance. Reservoir-induced entanglement is generated between two semiconductor dots in a microcavity where a quantum state encoded in a third quantum dot is then tuned into collective decay with one of the entangled dots. Teleportation is achieved automatically in our scheme which we also extend to quantum wires.
Shot-noise spectrum of superradiant entangled excitons
(2004-06-01)
Chen, YN
;
Brandes, T
;
Li, CM
;
Chuu, DS
;
電子物理學系
The shot noise produced by tunneling of electrons and holes into a double dot system incorporated inside a p-i-n junction is investigated theoretically. The enhancement of the shot noise is shown to originate from the entangled electron-hole pair created by superradiance. The analogy to the superconducting Cooper pair box is pointed out. A series of Zeno-like measurements is shown to destroy the entanglement, except for the case of maximum entanglement.
Spin relaxation in a GaAs quantum dot embedded inside a suspended phonon cavity
(2006-02-01)
Liao, YY
;
Chen, YN
;
Chuu, DS
;
Brandes, T
;
電子物理學系
The phonon-induced spin relaxation in a two-dimensional quantum dot embedded inside a semiconductor slab is investigated theoretically. An enhanced relaxation rate is found due to the phonon van Hove singularities. Oppositely, a vanishing deformation potential may also result in a suppression of the spin relaxation rate. For larger quantum dots, the interplay between the spin orbit interaction and Zeeman levels causes the suppression of the relaxation at several points. Furthermore, a crossover from confined to bulklike systems is obtained by varying the width of the slab.