OP: Spatial and spectral control of quantum dot single photon emitters for scalable photonic devices

University Of Delaware, Newark DE

Investigators

Abstract

Project title: Engineering materials for the scalable production of new electronic devices that use controlled emission and absorption of single photons Abstract Non-Technical: Modern photonic and electronic devices operate via the generation and transmission of many thousands of photons or electrons, respectively. Although scientists have known for many years that devices that operate with single photons or single electrons could enable revolutionary new functionality, it is extremely difficult to engineer reliable devices that operate at this level. For example, previous efforts to build a material that contains many independent but identical single photon emitters have failed because the emitters are formed at random locations and are not identical. The supported researchers will engineer a new material that overcomes this limit. First, the emitters will be forced to grow at specified locations by pre-patterning the surface on which the emitters grow. Second, each site will contain a pair of emitters whose interaction can be controlled to tune the emission to the value desired for device operation. This work will include sustained engagement with the students, parents, and teachers of an elementary school with an extremely high percentage of economically-disadvantaged students. Technical: Optoelectronic devices that operate at the quantum limit of single photons, charges, and spins have long been viewed as a promising platform for quantum device technologies. These quantum technologies promise many advances, including fundamentally secure modes of information transmission and exquisite sensors with very low detection thresholds. The ideal device would leverage wafer-scale semiconductor processing methods to create on-chip photonic devices that emit, route, manipulate, and absorb single photons. The fundamental component of such a device would have to be a single optically-active nanostructure with quantized energy states. However, efforts to create chip-scalable platforms for single-photon technologies have been hampered by the challenge of creating optically-active nanostructures with both spatial control of their position and spectral control over their emission energy. The approach to be taken in this project overcomes these challenges by leveraging two recent advances in molecular beam epitaxial growth. First, pre-patterned substrates will be used to spatially control the nucleation of "template" quantum dots (QDs) whose optical quality is unimportant. A series of these "template" QDs will be used to transfer the spatial pattern to a growth surface well-separated from the pre-patterned surface in order to obtain high optical quality from the QDs that are used for photon emission and absorption. Second, the optically-active structure will be a complex of two QDs stacked along the growth axis such that applied electric fields can be used to tune the optical absorption and emission wavelengths. Prior work on these coupled QD pairs by the PI shows that they can tune optical emission wavelengths over a range at least one order of magnitude larger than that available from single QDs. The team will embed the QD pairs within a p-i-n diode structure that enables the local application of electric fields to individual QD pairs. The individual wavelength tunability of each QD pair provides the mechanism for deterministic spectral overlap with target photonic device wavelengths.