Zeeman coherence and optical nonlinearity of magnetoexcitons in single quantum dots

G. Chen, D. Gammon, Lu Jeu Sham +1 more

Hideki Gotoh, Hidehiko Kamada, T. Saitoh +2 more

A. Krügel, Alexei Vagov

M. A. Antón, F. Carreño

Linear and nonlinear properties in an ensemble of single-hole spin InGaAs/GaAs quantum dots are theoretically studied. The application of a DC magnetic field in the semiconductor growth plane induces a Zeeman splitting of the hole levels which can be modeled like a four-level atom in the X -type configuration. All-optical and magneto-optical switching of a weak probe field are shown to be feasible in this system either by changing the Rabi frequency of an auxiliary control field or by changing the magnitude of the external magnetic field. We analyze the feasibility to store and release a weak pulse from the medium resulting from Zeeman coherent oscillations, thus the system is expected to be useful to develop a variable semiconductor optical buffer.

Steven T. Cundiff, M. Koch, Jagdeep Shah +2 more

The coherent response of magnetoexcitons is measured using two-pulse transient-four-wave-mixing. Spectral resolution shows that the magnetoexcitons are interacting and that they act as a single quantum mechanical system. Measurements at zero magnetic field yield insight by demonstrating that interactions between the exciton and continuum states can dramatically modify the coherent response. This is most evident in an experiment where coherent emission is observed from the 1s exciton resonance, although it is not excited by one of the pulses.

Gang Chen, E. Tabak, Duncan G. Steel +4 more

Summary form only given. We report the observation of an interesting coherent effect, which looks very much like the so-called Zeeman coherence in atomic physics and is indeed an optically induced entanglement between two oppositely oriented electrons confined to one single QD. This is the first observation of entanglement in semiconductors and is an important step in realizing a quantum logic device such as proposed for quantum computing.