Self-assembled InAs Quantum Dots (QDs) are often called “artificial atoms" and have long been of interest as components of quantum photonic and spintronic devices. Although there has been substantial progress in demonstrating optical control of both single spins confined to a single QD and entanglement between two separated QDs, the path toward scalable quantum photonic devices based on spins remains challenging. Quantum Dot Molecules, which consist of two closely-spaced InAs QDs, have unique properties that can be engineered with the solid state analog of molecular engineering in which the composition, size, and location of both the QDs and the intervening barrier are controlled during growth. Moreover, applied electric, magnetic, and optical fields can be used to modulate, in situ, both the spin and optical properties of the molecular states. We describe how the unique photonic properties of engineered Quantum Dot Molecules can be leveraged to overcome long-standing challenges to the creation of scalable quantum devices that manipulate single spins via photonics.
Rising efforts concerning the reduction of CO2 emission promote the use of fiber reinforced plastics, e.g. in automotive
or aircraft engineering due to their low mass compared to classical materials. Although fiber reinforced plastics have
critical properties such as low mass and high stiffness compared to classical materials, they also may suffer
unpredictable failures due to hidden structural damage. Thus structural health monitoring is vital for the development of
modern lightweight structures.
Our concept of material integrated sensor technology is based on a combination of a piezoelectric foil with a quantum
dot polymer composite. By application of a mechanical (over-) load, electrical charges are generated and injected into
the nanocrystals causing PL quenching, which is detectable as local optical contrast. A very efficient charge injection is
crucial for sensitive load detection, because of limited amount of generated charges and transport losses.
Consequently we have investigated the charge injection and charge storage properties of various types of quantum dots,
in particular core shell types CdSe/ZnS and InP/ZnS, embedded in semi-conducting poly(9-vinylcarbazole) (PVK). PL
quenching was realized by application of external voltages smaller than 20 V. Initial results indicated a longer charge
storage time in InP/ZnS quantum dots, which we attribute to a difference in band level alignment between valence band
levels of respective quantum dots and PVK.