We examine a graphene quantum dot formed by combining an electric and a uniform magnetic field. The electric field creates a smooth quantum well potential while the magnetic field induces an exponential tail to the dot states. The states peak in the well and the electrostatic barrier region as a result of the Klein tunneling effect. Coupling between dot states which peak in different regions ca...

We study electronic transport in quantum-dot structures made of graphene. Focusing on the rectangular dot geometry and utilizing the non-equilibrium Green's function to calculate the transmission in the tight-binding framework, we find significant fluctuations in the transmission as a function of the electron energy. The fluctuations are correlated with the formation of quantum scarring states,...

We report on the realization of few-electron double quantum dots defined in a two-dimensional electron gas by means of surface gates on top of a GaAs/AlGaAs heterostructure. Two quantum point contacts (QPCs) are placed in the vicinity of the double quantum dot and serve as charge detectors. These enable determination of the number of conduction electrons on each dot. This number can be reduced ...

The engineering of quantum dot solids with low defect concentrations and efficient carrier transport through a ligand strategy is crucial to achieve efficient quantum dot (QD) optoelectronic devices. Here, we study the consequences of various surface ligand treatments on the light emission properties of PbS quantum dot films using 1,3-benzenedithiol (1,3-BDT), 1,2-ethanedithiol (EDT), mercaptoc...

We study the emission line shapes of single CdSe nanocrystallite quantum dots. Single dot line shapes are found to result from rapid spectral shifting of the emission spectrum rather than the intrinsic physics of the quantum dot. A strong dependence of single dot line widths on excitation intensity, wavelength, temperature, and integration time is found and is correlated with the number of time...

We present Raman scattering by optical phonons in self-assembled Ge quantum dot superlattices grown by solid-source molecular beam epitaxy. The Ge quantum dots are vertically correlated and have different average sizes and dot morphologies. The GeGe optical phonon frequency was mainly caused by strain relaxation effects. Experimentally observed GeGe optical phonon modes were compared with calcu...

The energy levels of CdSe quantum dots are studied by scanning tunneling spectroscopy. By varying the tip−dot distance, we switch from “shell-filling” spectroscopy (where electrons accumulate in the dot and experience mutual repulsion) to “shell-tunneling” spectroscopy (where electrons tunnel, one at a time, through the dot). Shell-tunneling spectroscopy provides the single-particle energy leve...

Extreme photon localization is applicable to constructing building blocks in photonic systems and quantum information systems. A finding fact that photon localization in small space modifies the radiation process was reported in 1944 by Purcell, and advances in fabrication technology enable such structures to be constructed at optical frequencies. Many demands of building compact photonic syste...

Double quantum dots are convenient solid-state platforms to encode quantum information. Two-electron spin states can be detected and manipulated using quantum selection rules based on the Pauli exclusion principle, leading to Pauli spin blockade of electron transport for triplet states. Coherent spin states would be optimally preserved in an environment free of nuclear spins, which is achievabl...

Pb cations in PbS quantum rods made from CdS quantum rods by successive complete cationic exchange reactions are partially re-exchanged for Cd cations. Using STEM-HAADF, we show that this leads to the formation of unique multiple dot-in-rod PbS/CdS heteronanostructures, with a photoluminescence quantum yield of 45-55%. We argue that the formation of multiple dot-in-rods is related to the initia...