Negative Polarization through Photon to Electron Spin Polarization Transfer in GaAs Quantum Wells

Verification of polarization selection rules and implementation of selective coherent manipulations of hydrogenic transitions in n-GaAs

Electrons bound to shallow donors in GaAs have orbital energy levels analogous to those of the hydrogen atom. The polarization selection rules for optical transitions between the states analogous to the 1s and 2p states of hydrogen in a magnetic field are verified using Terahertz (THz) radiation from the UCSB Free Electron Laser. A polarization-selective coherent manipulation of the quantum states is demonstrated and the relevance to quantum information processing schemes is discussed.

Suppression of nuclear spin diffusion at a GaAs/AlGaAs interface measured with a single quantum dot nano-probe

Nuclear spin polarization dynamics are measured in optically pumped individual GaAs/AlGaAs interface quantum dots by detecting the time-dependence of the Overhauser shift in photoluminescence (PL) spectra. Long nuclear polarization decay times of ~ 1 minute have been found indicating inefficient nuclear spin diffusion from the GaAs dot into the surrounding AlGaAs matrix in externally applied magnetic field. A spin diffusion coefficient two orders lower than that previously found in bulk GaAs is deduced.

Spin Polarization of Photoelectrons in GaAs Excited by Twisted Photons

Inter-band photo-excitation of electron states with the twisted photons in GaAs, a direct band-gap bulk semiconductor, is considered theoretically. Assuming linearity of the quantum transition amplitudes and applying Wigner-Eckart theorem, we derive a plane-wave expansion of twisted-photon amplitudes and obtain relative probabilities for magnetic sub-level population of the photo-electrons in conduction band. The approach for calculating the position dependent electron polarization, resulting from photo-absorption of twisted light, is described for vertical transitions in the $Γ$ - point. Theo…

Optically induced nuclear spin polarization in a single GaAs/AlGaAs quantum well probed by a resistance detection method in the fractional quantum Hall regime

We study the optically pumped nuclear spin polarization in a single GaAs/AlGaAs quantum well in the quantum Hall system. We apply resistive detection via the contact hyperfine interaction, which provides high sensitivity and selectivity, to probe a small amount of polarized nuclear spins in a single well. The properties of the optical nuclear spin polarization are clearly observed. We theoretically discuss the nuclear spin dynamics accompanied with doped electrons to analyze the experimental data. The optical nuclear polarization spectra exhibit electron-spin-resolved lowest Landau level inter…

可调谐的正交GaAs纳米线产生的近红外偏振纠缠光子

Tunable polarization-entangled near-infrared photons from orthogonal GaAs nanowires

利用正交GaAs纳米线生成可调谐的近红外偏振纠缠光子，实现量子态的可控转变与高保真度

采用液滴刻蚀外延法生长的GaAs量子点作为量子光源

GaAs quantum dots grown by droplet etching epitaxy as quantum light sources

该研究综述了液滴刻蚀法制备的GaAs量子点作为量子光源的生长特性与光学性能，介绍了其在单光子、纠缠光子对产生及量子通信核心场景的应用进展与发展前景。