Unveiling the spin-singlet states of two electron-hole pair complexes using two-photon excitation in a GaAs/AlAs quantum dot (original) (raw)

Two-photon absorption by a quantum dot pair

Physical Review B, 2015

The biexciton absorption spectrum of a pair of InAs/GaAs quantum dots is being studied by photoluminescence excitation spectroscopy. An absorption resonance with the characteristics of an instantaneous two-photon process reveals a coherent interdot two-photon transition. Pauli-selective tunneling is being used to demonstrate the transduction of the two-photon coherence into a nonlocal spin singlet state. The two-photon transition can be tuned spectrally by electric field, enabling amplification of its transition strength.

Single photoelectron detection after selective excitation of electron heavy-hole and electron light-hole pairs in double quantum dots

Physical Review B, 2014

The rapid escalation of information processing and storage in the last decade has necessitated the development of novel technologies to ensure highly secured long distance communication. With recent advances in theoretical and experimental studies, quantum information is believed to be a potential candidate for future technology with absolutely secure information exchange. Major challenges in quantum information systems include long distance communication and multi-node networks, which require coherent coupling of photons to solid-state quantum bits (qubits) as used for implementing quantum memory and quantum entanglement. They are both fundamental elements for constructing a quantum repeater, distributed quantum computing and hybrid quantum information network .

Two-photon photoluminescence excitation spectroscopy of single quantum dots

Physical Review B, 2011

We present experimental and theoretical study of single semiconductor quantum dots excited by two non-degenerate, resonantly tuned variably polarized lasers. The first laser is tuned to excitonic resonances. Depending on its polarization it photogenerates a coherent single exciton state. The second laser is tuned to biexciton resonances. By scanning the energy of the second laser for various polarizations of the two lasers, while monitoring the emission from the biexciton and exciton spectral lines, we map the biexciton photoluminescence excitation spectra. The resonances rich spectra of the second photon absorption are analyzed and fully understood in terms of a many carrier theoretical model which takes into account the direct and exchange Coulomb interactions between the quantum confined carriers.

Correlated photon-pair emission from a charged single quantum dot

Physical Review B, 2005

The optical creation and recombination of charged biexciton and trion complexes in an (In,Ga)As/GaAs quantum dot is investigated by micro-photoluminescence spectroscopy. Photon cross-correlation measurements demonstrate the temporally correlated decay of charged biexciton and trion states. Our calculations provide strong evidence for radiative decay from the excited trion state which allows for a deeper insight into the spin configurations and their dynamics in these systems.

Control of Photon Polarization in GaAs/AlAs Single Quantum Dot Emission

Acta Physica Polonica A, 2007

We study polarization resolved correlation between photons emitted in cascaded biexciton-exciton recombination from a single quantum dot formed in type II GaAs/AlAs bilayer. Magnetic field induced transition from anisotropy controlled to the Zeeman controlled emission was demonstrated by a circular polarization correlation between the emitted photons. A simple model describing the effect allowed us to determine the anisotropic exchange splitting of the excitonic state. This method of the anisotropic exchange splitting determination can be useful in the case when other methods are not sensitive enough.

Entangled states of electron–hole complex in a single InAs/GaAs coupled quantum dot molecule

Physica E: Low-dimensional Systems and Nanostructures, 2002

We summarize here results of calculations and experiments on electron and valence hole states in a single pair of vertically stacked and electronically coupled InAs self-assembled quantum dots. In perfectly aligned quantum dots one can relate an electron-hole complex to a pair of entangled qubits. The information carried by individual qubit is related to the quantum dot index (isospin) of individual carrier. The quality of fabricated quantum dot molecules is identiÿed from the exciton ÿne structure in a magnetic ÿeld. ?

Probing excitons and biexcitons in coupled quantum dots by coherent two-dimensional optical spectroscopy

Physical Review B - PHYS REV B, 2009

We calculate two-dimensional (2D) photon-echo and double-quantum-coherence spectra of two coupled InGaAs/GaAs quantum dots at various distances, taking into account electron, hole, and exciton hopping. Signatures of direct and indirect excitons in two-exciton resonances are revealed. At short distances, electron delocalization contributes to the creation of new biexcitonic peaks, and dipole-dipole interactions shift the two-exciton energies.

Biexciton-Exciton Cascade Spectra In Quantum Dot Molecules

arXiv: Other Condensed Matter, 2007

We present photoluminescence studies of the molecular neutral biexciton-exciton cascade of individual vertically stacked InAs/GaAs quantum dot pairs. We tune either the hole or the electron levels of the two dots into tunneling resonances. The spectra are described well within a few-level, few-particle molecular model. Their properties can be modified broadly by an electric field and by structural design, which makes them highly attractive for controlling non-linear optical properties.

Voltage-Controlled Electron-Hole Interaction in a Single Quantum Dot

Journal of Superconductivity, 2005

The ground state of neutral and negatively charged excitons confined to a single self-assembled InGaAs quantum dot is probed in a direct absorption experiment by high resolution laser spectroscopy. We show how the anisotropic electron-hole exchange interaction depends on the exciton charge and demonstrate how the interaction can be switched on and off with a small dc voltage. Furthermore, we report polarization sensitive analysis of the excitonic interband transition in a single quantum dot as a function of charge with and without magnetic field.