Optical detection of quantum dynamics in gallium arsenide neutral donors

Oleg A. Ryabushkin, В. И. Сергеев

K. Takasago, Yoshihiro Ogawa, F. Minami

和浩 高砂, Yoshihiro Ogawa, FUJIO MINAMI

Kyle B. Ferrio

Optically induced coherences reveal key features of nonlinearities in the optical response of semiconductors and can be employed to obtain information about dynamical processes via such techniques as transient four-wave mixing and differential transmission. This thesis presents experimental observations of three previously unrecognized aspects of coherent nonlinear optical phenomena occurring in gallium arsenide and multiple quantum wells: excitation-induced dephasing, two-photon biexcitonic coherence, and electronic Raman coherence. Results are analyzed using optical Bloch equations, which emphasize the potential generalization to other semiconductor systems. Excitation-induced dephasing is similar to classical line broadening. The work in this thesis shows for the first time that this incoherent effect is directly responsible for the dominant coherent optical nonlinearity in bulk gallium arsenide. Exact analytic models show that excitation-induced dephasing accounts for the previously unexplained polarization and density dependence of four-wave mixing signals obtained at the 1s exciton resonances in gallium arsenide. This thesis also presents the first observation of the two-photon biexcitonic coherence in a gallium arsenide multiple quantum well using a modified Michelson phase-conjugate interferometer to directly observe the 770-Terahertz oscillation of the nonradiative superposition of the electronic ground state and the biexciton state. The contribution of the two-photon coherence to the nonlinear optical response is thereby confirmed, in addition to the well-known stepwise biexcitonic response. Finally, the short-lived electronic Raman coherence between the light- and heavy-hole 1s excitons in gallium arsenide is conclusively demonstrated for the first time. The Raman coherence provides direct access to dephasing processes not detectable in conventional linear spectroscopy. Similar non-radiative coherences are related to population trapping, electromagnetically induced transparency, and lasing without inversion in atomic systems, and the new observations in gallium arsenide suggest that analogous phenomena may occur in semiconductors.

Christof Peter Dietrich, Andrea Fiore, Mark G. Thompson +2 more

The recent progress in integrated quantum optics has set the stage for the development of an integrated platform for quantum information processing with photons, with potential applications in quantum simulation. Among the different material platforms being investigated, direct-bandgap semiconductors and particularly gallium arsenide (GaAs) offer the widest range of functionalities, including single- and entangled-photon generation by radiative recombination, low-loss routing, electro-optic modulation and single-photon detection. This paper reviews the recent progress in the development of the key building blocks for GaAs quantum photonics and the perspectives for their full integration in a fully-functional and densely integrated quantum photonic circuit.

A. C. Schaefer, N. H. Bonadeo, Duncan G. Steel